Gradient chaotropic regulation of Zn^2+ solvation chemistry for low-temperature zinc metal batteries

Domain: chemistry
Published: 2025-12-20
Editorial outcome: minor_revision

Abstract
Aqueous zinc-ion batteries have emerged as a promising system for safe and sustainable energy storage. However, their practical application is hindered by detrimental interfacial side reactions and inadequate low-temperature performance. Herein, we report the design of a gradient chaotropic ionic liquid (IL)-based aqueous electrolyte (Emim⁺-TFA⁻/OTf⁻-Zn2+-H O), which can simultaneously fulfil the conflicting demands of dendrite-free zinc deposition and low-temperature operation. By forming an antifreeze electrolyte with a hydrophobic yet salt-philic interface, the proposed formulation overcomes the limitations of conventional IL-based systems that rely on H O-lean compositions, complex additives, or elaborate solvent mixtures. Thus, the assembled zinc-ion cells exhibit improved zinc plating/stripping stability. At a current density of 0.1 mA cm−2 and 0.1 mAh cm−2, the Zn||Zn symmetric cells endure prolonged zinc plating/stripping, exceeding 13,000 h at −30 °C and 6690 h at −40 °C. In full cells, Zn||VO @VO maintain nearly 100% capacity retention over 3500 cycles at 0.2 A g−1 and −40 °C. This gradient chaotropic Zn2+ electrolyte design provides a versatile platform for effective antifreeze Zn2+ solvation chemistry and accelerated interfacial ion transport, enabling high-performance zinc batteries in subzero environments.

Introduction
With the growing demand for safe and sustainable alternatives to non-lithium-based systems, aqueous zinc metal batteries (ZMBs) are gaining increasing attention for future stationary energy storage systems, due to their intrinsic safety, economic viability, and satisfactory performance. However, the zinc metal negative electrode is thermodynamically instability in aqueous electrolytes, leading to irreversible parasitic reactions including hydrogen evolution and the formation of by-products (e.g., ZnO, Zn(OH) 2−). Besides, internal short circuits and eventual battery failure can occur because of uncontrolled zinc dendrite growth, which originates from uniform Zn2+ deposition at the electrode interface. Furthermore, when the temperature drops below 0 °C, H O molecules in the electrolyte tend to form additional hydrogen bonds (H-bonds, ~0.52 per molecule), driving a transition from a disordered liquid state to an ordered crystalline structure, resulting in ice formation. Therefore, despite their high ionic conductivity, aqueous electrolytes are prone to freezing at low temperatures, which significantly hinders Zn2+ transport and reduces battery lifespan. Thus, these challenges restrict the practical implementation of ZMBs, especially under low-temperature conditions.

Various approaches have been explored to overcome the challenges associated with zinc metal negative electrodes, such as constructing protective interfacial layers, introducing functional additives, and designing co-solvent systems. Among these strategies, co-solvent engineering is an effective approach for simultaneously stabilizing the zinc metal negative electrode and enhancing low-temperature tolerance. Co-solvents act by disrupting the structured H-bonds network of aqueous electrolytes, reducing interfacial H O activity and promoting solvent-salt decoupling, which collectively contribute to improved negative electrode stability and antifreeze performance. It is crucial to minimize interface H O activity to further enhance the electrochemical performance of zinc metal negative electrodes. However, conventional strategies based on hydrophobic or H O-lean interfacial designs would inevitably increase interfacial resistance and impede Zn2+ transport kinetics, compromising battery performance under cold conditions. Furthermore, excessive incorporation of antifreeze co-solvents would significantly lower ionic conductivity, which induces severe concentration polarization, dendrite formation, and parasitic side reactions. As a result, simultaneously protecting the zinc negative electrode from side reactions, regulating Zn2+ deposition, and lowering the freezing point of aqueous electrolytes to improve the low-temperature performance of ZMBs presents a significant challenge for electrolyte engineering.

Compared with the above-mentioned methods, optimizing electrolytes will directly regulate the solvation structure to decrease the H O activity, reducing the possibility of side reactions. The anions or organic fractions tend to form a stable solid-electrolyte interphase (SEI) by electrochemical decomposition or spontaneous chemical reactions, facilitating a high-quality Zn2+ stripping/plating process. Significantly, certain ionic species or specific functional groups in the electrolyte can disrupt the H-bonds network of H O, lowering the freezing point of aqueous electrolytes. From these design perspectives, ionic liquids (ILs) are ionic compounds composed of organic cations and anions, featuring tunable structures and functionalities, making them ideal candidates for comprehensive electrolyte-component regulation. Attributable to their inherent merits, such as high ionic conductivity, high electrochemical stability, wide electrochemical window, low volatility, and low melting points, ILs have been widely utilized as electrolyte additives in ZMBs. Correspondingly, extensive research has been devoted to tailoring cation-anion chemistry to optimize their electrochemical performance. Specifically, the steric shielding effect and hydrophobicity of bulky IL cations help stabilize the zinc surface, while reactive anions participate in interfacial chemistry to form an inorganic-rich layer (e.g., ZnF , ZnCO , ZnO, and ZnS) with fast ion-conducting pathways. Nevertheless, their role in forming a H O-deficient electric double layer (EDL) at the zinc negative electrode necessitates precise content control, as excessive amounts may hinder ion transport and interfacial kinetics due to their inherent hydrophobicity and cation-shielding effects. Alternatively, ILs have been employed in H O-lean quasi-solid or solid electrolytes, aiming to eliminate active H O and construct highly stable zinc battery systems, albeit at the expense of ionic conductivity. As a result, only a few studies have explored the combination of ILs with other antifreeze solvents to develop low-temperature electrolytes. However, the introduction of such co-solvents always leads to a significant decrease in ionic conductivity, safety risks, environmental concerns, and poor compatibility with implantable biomedical applications. Therefore, using ILs as comprehensive electrolyte regulators in aqueous systems to optimize both interfacial structure and low-temperature performance remains challenging and often requires additional modulation with complex co-solvents or engineered additives, increasing system complexity and cost. The Hofmeister series, also known as ion-specific effects, categorizes ions based on their relative capacity to influence protein solubility in solutions, resulting in a characteristic ordering. Ions identified as chaotropic anions exhibit a pronounced ability to destabilize protein conformation and stability. Moreover, it has been confirmed that they will break the H-bonds network formed by H O molecules.

Herein, we propose a holistic component-modulation engineering for aqueous electrolytes, achieving robust Zn2+ solvation chemistry and enhanced electrochemical performance in aqueous zinc-based batteries. Taking ILs as a demonstration, we introduce a gradient chaotropic Zn2+ electrolyte formulation to construct antifreeze Zn2+ solvation chemistry and achieve improved zinc metal negative electrode stability. Retaining the interfacial EDL modulation capability of hydrophobic bulky cations, the gradient chaotropic anions were introduced to mitigate the excessive accumulation of IL cations at the interface, allowing ILs to effectively function as a single co-solvent in aqueous electrolytes. Both theoretical calculations and a series of in-situ/ex-situ characterizations demonstrate that the proposed electrolyte configuration fundamentally transforms the Zn2+ solvation chemistry, yielding an antifreeze electrolyte with a hydrophobic yet salt-philic interfacial environment. This transformation profoundly alters the H-bond networks within aqueous Zn2+ electrolytes, promoting the formation of an H O-deficient and Zn2+ conductive SEI layer, and effectively suppressing the dissolution of metal oxide positive electrodes. Thus, stable cycling performance is achieved even under low-temperature conditions. At 25 °C, the zinc negative electrode delivers a zinc plating/stripping lifespan nearly 25 times longer than that in the blank electrolyte under 1.0 mA cm−2 and 1.0 mAh cm−2. Besides, Zn||Zn symmetric cells achieve stable operation for over 13,000 h at −30 °C and 6692 h at −40 °C (0.1 mA cm−2, 0.1 mAh cm−2). Significantly, at a temperature of −40 °C, the Zn||VO @VO presents virtually no decline in discharge-specific capacity over 3500 cycles under 0.2 A g−1. Our electrolyte formulation could establish a versatile platform for effective antifreeze Zn2+ solvation chemistry and highly stable ZMBs.

Results
Reconstructing Zn2+ solvation chemistry via ILs
The proposed gradient chaotropic Zn2+ electrolyte was prepared by introducing 1-Ethyl-3-methylimidazolium trifluoroacetate ([Emim][TFA], denoted as EFA) as a single cosolvent into a zinc trifluoromethanesulfonate-H O (Zn(OTf) -HO) electrolyte system. Firstly, the associated interactions between these ions are weakened due to the significant volume difference between the cations and anions of the Zn(OTf) -HO-EFA system. Secondly, the independently dispersed Emim+ possesses the positively charged imidazolium ring that prefers to absorb on the surface of the zinc surface, which is conducive to decreasing the free H O molecules in the inner Helmholtz plane (IHP). Attributed to the spontaneous electrostatic reaction, the positively charged IHP promotes the accumulation of anions within the EDL, forming an anion-derived SEI in the subsequent cycle. Thirdly, the TFA− anions from Emim-based ILs and the OTf− anions from zinc salts are relatively inert and are positioned adjacent in the Hofmeister series. As prototypical chaotropic anions, they will cooperate to disrupt the H-bonds network and modulate the molecular organization of H O, resulting in increased structural disorder and lowering the freezing point of the whole electrolyte. Its strong coordination affinity further enables reversible Zn2+ ion transport across the IL-modified IHP, whereas the adjacent chaotropic OTf− anion introduces moderate hydrophobic character to the electrolyte, contributing to interfacial stability.

Density Functional Theory (DFT) calculations were employed to elucidate the regulatory effect of EFA on the EDL structure. The results reveal that the adsorption energy of Emim+ on the surface of zinc foils significantly exceeds that of the anions (TFA− and OTf−) and H O. This strong interaction ensures the preferential adsorption of Emim+ onto the electrode surface, rather than H O, resulting in a reduction in interfacial H O content. Additionally, the binding energies of the Emim+-TFA− (−0.527 eV) and Emim+-OTf− (−0.528 eV) are notably higher than Emim+-H O (−0.215 eV), demonstrating that anions are preferentially migrating into and aggregating in IHP. Classical molecular dynamics (MD) simulation displays the distribution of ions and molecules near the zinc negative electrode surface. The abundant H O molecules aggregate within the ~5–10 Å from the surface of the zinc negative electrode in the blank electrolyte. However, strong adsorption of Emim+ via its hydrophobic alkyl chains, together with robust ion pairing with chaotropic anions, impedes H O from accessing the zinc surface, thereby reducing interfacial H O and producing a hydrophobic, salt-philic interface. Thus, a robust SEI with high conductivity, composed of ZnF , ZnO, ZnS, and ZnCO , is formed on the surface of the zinc negative electrode, due to the formation of H O-poor and anion-rich EDL.

Electrostatic potential (ESP) analysis and the results of binding energies reveal that the TFA⁻ possesses a stronger interaction with Zn2+ compared to those in H O and OTf⁻. Therefore, different from traditional electrolytes ([Zn(H O) ]2+), the anions will partly replace the H O molecule in the Zn2+-H O structure in the electrolyte to reshape the coordination environment of Zn2+. To further investigate the Zn2+ solvation structures across different electrolytes, MD simulations were performed. In the Zn2+-OTf⁻-H O system (blank electrolyte), H O molecules form the inner solvation shell by coordination with Zn2+. For the EFA-containing electrolyte, the anions tend to partly replace the H O and access the first solvation shell of Zn2+. Radial distribution function (RDF) and coordination number (CN) analysis can quantify the number of TFA− participating in the initial solvation layer. The CNs of Zn-O (H O), Zn-TFA−, and Zn-OTf− of 4.9, 0.75, and 0.35, respectively, a well-defined complex of [Zn(HO) (TFA−) (OTf−) ]+. The decreasing H O ratio in the inner solvation layer will mitigate the HER and side reaction caused by active H O.

To evaluate the essential role of gradient chaotropic anions (as opposed to a single species) in optimizing solvation structure and electrochemical performance, we substituted EmimTFA with 1-ethyl-3-methylimidazolium trifluoromethanesulfonate ([Emim][OTf], denoted as ETF) and conducted detailed solvation structural characterization. As shown in the Zn K-edge X-ray absorption near-edge structure (XANES) spectra, the lowest absorption edge of zinc foil is due to its zero-valence state. Solvated species differ in electron-donating ability, and these differences drive the changes in absorption edge energy across electrolytes. Therefore, the lower energy of EFA demonstrates that the chaotropic anions (OTf− and TFA−) donate more electrons to Zn2+ and the existence of more contact ion pairs (CIP). The local coordination environment of the Zn2+ solvation shell was investigated by Fourier-transformed extended X-ray absorption fine structure (FT-EXAFS) spectra and wavelet-transformed extended X-ray absorption fine structure (WT-EXAFS). Compared with the blank and ETF-containing electrolytes, the lower Zn-O peak in EFA-containing electrolytes indicates reduced Zn2+-H O coordination in the Zn2+ solvation structure. Furthermore, a split feature at 2.16 Å is indicative of Zn-F (TFA−) coordination, originating from direct interactions between Zn2+ and the F atoms of the chaotropic anions. These results confirm the coordination of chaotropic anions and Zn2+. The results of WT-EXAFS further confirm this conclusion. Small-angle X-ray scattering (SAXS) proves the evolution of the solvation structure of Zn2+ in various electrolytes. A broad scattering peak at 1.86 Å−1 accompanied by an enlarged 2D SAXS scattering ring is characteristic of a classical aqueous hydration shell in blank electrolytes. In the presence of IL, the lower-q peak and the smaller 2D SAXS ring are consistent with an increased real-space correlation length (d=2π/q) and larger solvation nanoclusters. Importantly, the 2D SAXS pattern for the EFA-containing electrolyte exhibits a blurred ring contour, in contrast to the ETF system. This difference confirms a more disordered solvation structure, where gradient chaotropic anions of TFA⁻ and OTf⁻ have successfully penetrated and replaced H O molecules in the Zn2+ solvation shell. Furthermore, the 2D 19F-1H heteronuclear Overhauser spectroscopy (HOESY) provides effective evidence for the breaking of the H-bond network by the gradient chaotropic anions. Compared with the blank and ETF-containing electrolytes, where only F(OTf−)-H(HO) interactions are observed (inside the brown circles), the EFA exhibits a coupling peak between F(TFA⁻) and H(H O) (inside the blue circles), confirming the cooperation of these anions in breaking the H-bond network.

To elucidate the cosolvent effect of EFA, a series of electrolytes with varied EFA concentrations was formulated and subjected to comprehensive physicochemical and electrochemical characterization. As depicted in Supplementary Fig. 4a, compared with the blank electrolyte, 1H Nuclear Magnetic Resonance spectroscopy (1H NMR) peaks of EFA-containing electrolytes are collectively shifted downfield, indicating a decreased electron density and proton shielding in H O. This phenomenon is attributed to the disruption of the original intermolecular H-bond network of H O by the chaotropic anions. As the EFA concentration increased, the ¹H peak progressively shifted upfield, indicating the gradual release of H O molecules from the Zn2+ solvation shell, thereby increasing the involvement of anions in the Zn2+ solvation environment.

The evolution of the Zn2+ solvation structure and H-bonds as different proportions of EFA were added was further probed using Fourier transform infrared (FTIR) and Raman spectroscopies. The corresponding Zn2+-solvating peaks become more pronounced as the amount of IL increases. The O-H stretching band of H O molecules exhibits a broad absorption range between 3800~2800 cm−1, corresponding to various H-bond strengths from weak to strong interactions. With increasing EFA concentrations, the percentage of strong hydrogen (S-H) bonds decreased significantly, while that of weak hydrogen (W-H) bonds increased. This result is ascribed to TFA− ions acting as H-bond acceptors, disrupting the original H-bond network. The Raman spectra revealed the –SO vibrational band (1010~1050 cm−1) of OTf−, which could be further deconvoluted into three distinct components: free anions (FA, OTf⁻, 1023 cm−1), solvent-separated ion pairs (SSIP, Zn2+-H O, 1030 cm−1), and CIP (Zn2+-TFA−-OTf−, 1035 cm−1). The proportion of CIPs increases upon the addition of EFA, which facilitates the formation of an anion-derived ion-conductive SEI. Such an anion-rich solvation structure, modulated by the gradient chaotropic anions, further induces substantial H-bonds disorder within the electrolyte matrix. Based on the gradient chaotropic anions and the bulk Emim+ cations, these results demonstrate that the disruption of the H-bond network in EFA-containing electrolytes, coupled with the formation of an anion-rich solvation structure, facilitates the suppression of side reactions and fosters uniform Zn2+ deposition at both low and ambient temperatures.

Gradient chaotropic Zn2+ electrolyte for zinc metal compatibility
The effects of EFA in improving zinc charge/discharge behavior are evaluated by Zn||Zn symmetric cells. In 20% EFA electrolyte, the cell demonstrates a steady zinc plating/stripping behavior over 2500 h at 1.0 mA cm−2, 1.0 mAh cm−2 (at 25 °C). By comparison, the cell failed after only 125 h in the blank electrolyte, primarily attributed to the uncontrolled zinc dendrites growth. In addition, the Zn||Zn cells in 10, 30, and 40% EFA electrolyte exhibit stable zinc plating/stripping performance of 480, 450, and 370 h, respectively. However, increasing the EFA concentrations (such as 70% EFA and 90% EFA) leads to a decline in cycle life, accompanied by a significant voltage polarization increase, which may stem from the high viscosity of EFA impeding ion transport.

The ion conductivity of the EFA-containing electrolyte is decreased from 4.58 to 2.24×10−2 S cm−1 with the increase of EFA. As the performance observed above, the 20% EFA electrolyte is identified as an optimized formulation for subsequent characterizations and electrochemical testing. As anticipated, the zinc negative electrode in the 20% EFA electrolyte stabilizes for more than 5400 cycles at 20.0 mA cm−2, 1.0 mAh cm−2, markedly outperforming the blank electrolyte. To probe its feasibility under the practical conditions, Zn||Zn symmetric cells were subjected to high depth of discharge (DOD) testing. When the high DOD is increased to 81.2%, the symmetrical cell with 20% EFA delivered a stable plating/stripping process over 780 h, which is significantly longer than the cells assembled using blank electrolytes (about 20 h). Attributed to the establishment of H O-poor and anion-rich EDL, the cell with the hybrid electrolyte illustrates an enhanced rate capability. The cell in 20% EFA electrolyte can cycle stably even after experiencing a high current density of 45.0 mA cm−2 and 1.0 mAh cm−2, indicating an enhanced reaction kinetics. Besides, the Zn||Cu cell in the 20% EFA displays a significantly prolonged zinc plating/stripping processes with an average coulombic efficiency (CE) over 99.3% during the whole 1000 cycles at 5.0 mA cm−2 and 1.0 mAh cm−2. In comparison, in the blank electrolyte, the cell suffers from a decay within the initial 50 cycles, primarily attributed to parasitic reactions driven by the presence of free H O at the electrode-electrolyte interface.

In-situ electrochemical impedance spectroscopy (EIS) was performed during the zinc plating/stripping processes of Zn||Zn symmetric cells to evaluate the distribution of relaxation times (DRT), which enables comprehensive tracking of the zinc deposition/dissolution behavior and decouples the relationship between H O-poor and anion-rich EDL and the electrochemical performance. The peaks along with the relaxation times (τ) from 10−5 to 10 s confirm the relaxation of electrons (C), the absorption and desolvation of the [Zn(HO) ]2+ on the interface (C), the migration and crystallization of Zn2+ and zinc atom on the electrode (C ), and electron transfer and ion diffusion (C ), respectively. Compared with the blank electrolyte, the cell with 20% EFA stabilizes after only the first cycle and with a smaller τ value, demonstrating a stabler interfacial and faster interface reaction kinetics. X-ray diffraction (XRD) results confirm the interfacial stability of the electrodes. The distinct characteristic peaks corresponding to by-products (Zn (OTf)(OH) ·H O) are observed after zinc plating/stripping in the blank electrolyte. In contrast, the H O-poor and anion-rich EDL formed in 20% EFA effectively suppresses side reactions. In addition, an enhanced (002) crystal plane is observed, indicating a dense (002) oriented deposition, which is attributed to the preferential adsorption of Emim+ on the (002) crystal planes, thereby reducing the growth rate of this plane and resulting in the final exposure of (002)-oriented texture. To further corroborate the preferred zinc deposition along the (002) plane, 2D grazing incidence wide-angle X-ray scattering (2D GIWAXS) complemented by XRD texture analysis was used to perform detailed structural characterization. After zinc plating/stripping in the blank electrolyte, the negative electrode displays weak and diffuse Debye–Scherrer rings corresponding to the (101), (100), and (002) planes of zinc, suggesting polycrystalline and randomly oriented deposition. However, the negative electrode cycled in the 20% EFA shows a sharp and continuous diffraction ring assigned to the (002) plane, indicating highly oriented crystallization. These results are further supported by the (002) pole figures analysis. In contrast with the blank electrolyte, the negative electrode cycled from the 20% EFA electrolyte displays a pronounced high-intensity region at the center. These results unambiguously confirm that the EFA will promote the Zn (002) oriented deposition. Scanning electron microscopy (SEM) and atomic force microscopy (AFM) patterns reveal the zinc deposition morphology in electrolytes. In the blank electrolyte, the Cu substrate in the Zn||Cu cell shows an uneven surface, along with significant separator contamination after 50 cycles at 1.0 mA cm−2, 1.0 mAh cm−2. The results of AFM further confirm the heterogeneous morphology with a huge height variation. A denser zinc deposition layer forms on the Cu substrate in 20% EFA, aligning with the AFM results.

As mentioned above, these anions are aggregated in the IHP. Using frontier molecular orbital theory, the stability of various complexes in the electrolyte was investigated. Although Zn2+-HO exhibits the highest reduction propensity, the strong adsorption of Emim⁺ effectively excludes interfacial H O, thereby preventing H evolution and corrosion caused by H O decomposition. The lowest unoccupied molecular orbital (LUMO) value of [Zn2+-OTf−]+ (−2.69 eV) is lower than that of [Zn2+-TFA−]+ (−2.49 eV), suggesting that the [Zn2+-OTf−]+ complex is preferred to decomposition. These findings suggest that the anions prefer to decompose preferentially, and simultaneously form a high-conductivity SEI on the surface of the zinc negative electrode. To verify that the highly ion-conductive and anion-derived SEI, the composition of zinc deposits after plating/stripping was characterized and analyzed. As demonstrated in Fig. 3a, the zinc deposits are tightly covered by a moderately thick layer of SEI, about 30 nm. Especially, those inorganic compounds such as ZnF , ZnS, ZnO, and ZnCO are distributed in the SEI. Ar+ sputtering X-ray Photoelectron Spectroscopy (XPS) and Time-of-flight secondary-ion mass spectrometry (TOF-SIMS) reveal the spatial distribution of these compounds in SEI. In F 1s spectra, the peaks at 688.1 eV and 685.5 eV are associated with the –CF and ZnF , respectively. As the etching progresses, the peaks belonging to the ZnF are gradually obvious, which can be attributed to the decomposition of the anion (OTf− and TFA−). One detail that needs to be noted is that when the etching depth continues to 30 nm, the peak value attributed to –CF disappears. Similarly, a predominant ZnS (162.6 eV) signal and a diminished –CF SO (169.9 eV) peak are displayed in the S 2p spectrum. The intensity of –CF signal (293.0 eV, C 1s spectrum) and C=O/S-O signal (533.9 eV, O 1s spectrum) derived from the incomplete reduction of anions decreases with the etching process. The inorganic component of ZnCO in SEI is attributed to the dissolution of CO and the TFA− decomposition. Besides, the favorable composition of ZnO is observed after etching. Reversely, in the blank electrolyte, the high content of organic components can still be detected in the later stage of the etching process. Based on the above analysis, it is reasonable to propose that the robust inorganic nanocrystalline compounds constitute the predominant component of the SEI, facilitating Zn2⁺ transport in 20% EFA electrolyte. Furthermore, most organic compounds are distributed in the outer layer of the SEI, isolating the active H O to inhibit the side reactions and adapting the electrode volume variation in zinc plating/stripping. For the blank electrolyte, the randomly distributed compounds in the SEI could not effectively suppress the side reactions and dendrite formation. TOF-SIMS further confirm the absolute occupation of these inorganic compounds ZnF , ZnO, ZnS, and ZnCO in the SEI layer of the zinc negative electrode after plating/stripping in 20% EFA electrolyte. The structural contrast between SEI layers formed with and without EFA is clearly depicted in Fig. 3f, g.

Uniform zinc deposition and suppression of side reactions
Contact angle measurements show improved interfacial wettability with the 20% EFA electrolyte (58.4°) compared to the blank electrolyte (79.2°), which will promote more uniform zinc deposition. The zeta potential of zinc powder increases from −4.11 mV to 6.21 mV with EFA addition, resulting from the anchoring of Emim⁺ cations on the zinc surface. At the same time, the differential capacitance curves demonstrate a considerable decrease in 20% EFA electrolyte. This result corresponds to the Zeta potential test findings, which originated from the replacement absorption of bulky Emim+ to H O, leading to a thicker EDL. The nucleation overpotential of Zn2+ is notably higher in the 20% EFA electrolyte (90.0 mV) than in the blank electrolyte (46.5 mV), which will promote the uniform and dense deposition of Zn2+. To observe the influence of EFA on Zn2+ deposition, in-situ optical microscopy was employed. In the blank electrolyte, zinc deposits agglomerate at specific sites due to the “tip effect”, leading to loosen and nonuniform dendrites. In contrast, in the 20% EFA electrolyte, a compact and uniform zinc deposition layer is formed during the plating process.

The effectiveness of the Emim⁺-rich EDL in suppressing side reactions was further confirmed by Tafel and linear sweep voltammetry (LSV) analyses. The addition of EFA shifts the hydrogen evolution reaction (HER) potential from 0.09 V to −0.11 V and lowers the corrosion current density from 28.8 mA cm−2 to 8.13 mA cm−2. Meanwhile, the results of in-situ electrochemical Gas Chromatography (EC-GC) measurement and in-situ pH test directly confirm the inhibition effect of H evolution by EFA. After 120 min at 30 mA cm−2, 51.60 ppm H is detected in the blank electrolyte, which greatly exceeds 20% EFA (4.90 ppm). It’s worth noting that the pH value of 20% EFA is 3.97, which may be due to the hydrolysis of TFA−. Nonetheless, the in-situ formation of a stable SEI during zinc plating/stripping effectively protects the zinc surface, inhibiting further reactions with the electrolyte. Within 30 min at 5.0 mA cm−2, the pH value of the blank electrolyte increases significantly, from 4.98 to 5.45, which is higher than that of the 20% EFA (3.97 to 4.1). This much less pH variation and H evolution amount strongly indicate suppressed HER in the 20% EFA electrolyte system. The dynamic interface microevolution of the zinc negative electrode during plating/stripping has been characterized by in-situ FTIR. The relative absorption intensity of v(SO ) (OTf−) shows a sustained negative drift. The consumption of the W-H bond plays a dominant role in the evolution of the H-bonds. These results reveal the fact that uncontrolled consumption of both active H O and OTf− on the surface of the zinc negative electrode promotes severe H evolution and side reactions in the blank electrolyte during zinc plating/stripping, resulting in a rapid decline of the cell’s performance. However, the addition of EFA significantly reduces free H O molecules at the electrode interface due to the absorption of Emim⁺. The conversion of W-H to S-H/M-H directly confirms the suppression of H evolution. Furthermore, the reversible decrease and increase in the absorption intensity of the v(SO ) (OTf−) during zinc plating/stripping indicate a dynamic and reversible process of desolvation/resolvation. COMSOL Multiphysics simulations were employed to analyze the distribution of electric field intensity and Zn2+ concentration across the negative electrode surface. The 20% EFA electrolyte promotes the formation of a relatively positive electrostatic layer, due to the preferential adsorption of Emim⁺ cations, which effectively homogenizes the interfacial electric field distribution, as supported by electric field intensity simulations. Besides, the simulated Zn2+ concentration profiles reveal a more homogeneous ion distribution in the presence of EFA, indicating suppressed ion accumulation and depletion effects. Inversely, in blank electrolytes, a mass of Zn2+ accumulates at the tips of the protrusions, and an uneven electric field is observed, leading to the disordered growth of zinc dendrites during the plating/stripping process.

Electrochemical evaluation of Zn||VO @VO full cells
To evaluate the practical performance of the 20% EFA electrolyte, Zn||VO @VO cells were constructed. The corresponding material characteristics are provided in Supplementary Fig. 14. Compared with blank electrolytes, the cyclic voltage (CV) of cells in 20% EFA shows similar redox peaks with a higher current signal, indicating a more beneficial electrochemical reactivity. The rate capability of Zn||VO @VO cells is exhibited in Fig. 5a, delivering discharge-specific capacities of 325.44, 302.34, 278.39, 248.36, 201.47, and 161.14 mAh g−1 at specific currents of 0.2, 0.5, 1.0, 2.0, 5.0, and 10.0 A g−1, respectively, in 20% EFA electrolyte. Upon reverting to 0.2 A g−1, a high capacity of 313.81 mAh g−1 was recovered, confirming their enhanced rate capability.

To rule out that the improved battery performance originates merely from the specific anion effect rather than the increased ionic concentration, the cycling ability of cells using the different electrolytes is systematically compared. As shown in Supplementary Fig. 15b, at 2.0 A g−1, the cells with 20% EFA demonstrate significantly enhanced cycling stability (86.6% capacity retention, 500 cycles), whereas the blank and 3 M Zn(OTf) electrolyte exhibit rapid capacity decay with a capacity retention of about 22.2% and 68.5%, respectively. These results conclusively confirm the highly stable electrochemical performance of cells from the EFA-induced reconstruction of the solvation structure, H-bond, and EDL environment, rather than a trivial concentration increase of ions.

Besides, the stability and reliability of cells are also measured by performing self-discharge. Compared with the blank electrolyte (58.6%), the Zn||VO @VO in 20% EFA retains 88.12% of its initial capacity after 24 h resting, suggesting the effectiveness of EFA for electrode protection. Static soaking and in-situ Raman experiments are conducted to systematically evaluate the vanadium dissolution inhibition effect of EFA on positive electrode materials. As shown in Supplementary Fig. 16, the blank electrolyte exhibits marked discoloration after 14 days, indicating a serious vanadium dissolution. In contrast, the 20% EFA electrolyte demonstrates only subtle color variation, suggesting effective vanadium dissolution inhibition. Similarly, in-situ Raman spectroscopy characterization reveals distinct differences in the vanadium dissolution behavior of VO @VO between the electrolyte systems. In the process of charge-discharge cycling, the blank electrolyte shows characteristic vibration of δ(-O-V-O-V-, 150 cm−1) and δ(V=O, 260 cm−1), indicating a large amount of vanadium is dissolve from the framework into the electrolyte, which ultimately will lead to the fading of cell’s capacity. Differently, the 20% EFA shows no detectable vanadium-related vibrational signatures, confirming a suppressed vanadium dissolution. The stability of VO @VO in the 20% EFA is further demonstrated in the long-cycle performance test. After 3000 cycles, the Zn||VO @VO cell in 20% EFA delivers a high-capacity retention of 75% at 10.0 A g−1. In contrast, cells using blank electrolyte suffered from rapid capacity decay, with discharge capacity nearly disappearing after 2000 cycles. Furthermore, a 4×4 cm pouch cell is fabricated to evaluate the effectiveness of EFA on practical application. Following activation and stabilization, the cell, with a high active mass loading of approximately 10.0 mg cm−2, delivered a stable capacity of 202.1 mAh g−1 and maintained 132 mAh g−1 after 500 cycles at 1.0 A g−1, demonstrating sufficient power to successfully operate a mobile phone, demonstrating its practical viability. As shown in Supplementary Figs. 17d and 18 and Supplementary Table 1, the pouch cell demonstrates a considerable energy density.

Effective antifreeze Zn2⁺ solvation chemistry
According to the Hofmeister series, TFA⁻, as a typical chaotropic anion, disrupts the intrinsic H-bond network of H O, thus significantly depressing the freezing point of the electrolyte. Meanwhile, the TFA− and OTf− exhibit Hofmeister series compliance, with their chaotropic potency demonstrating a gradient enhancement. This gradient combination establishes an anion-rich solvation shell ([Zn(H O) (TFA−) (OTf−) ]+), favoring the deposition of Zn2+. The regulation mechanism of TFA− on the H-bond of bulk electrolyte is shown in Fig. 6a. The restructuring of H-bond networks in the electrolyte, driven by highly chaotropic anions, significantly decreases its freezing point. As shown in Fig. 6b, for blank electrolytes, an exothermic peak at −19.18 °C is ascribed to the crystallization of the electrolyte. The frozen electrolyte will lead to a separation electrolyte/electrode interface, resulting in an assignable interface impedance. Besides, the limiting ion migration does not provide sufficient ion conductivity to support effective cycling at low temperatures. With the addition of the EFA, the original H-bond network corresponding to the HO is broken, causing a greatly lower freezing point of the 20% EFA electrolyte (−53.21 °C) and providing a high ion conductivity of about 2.2 1 mS cm−1 at −40 °C. Therefore, the low freezing point ensures that the cell in 20% EFA electrolytes can operate stably at low temperatures. Besides, the activation energy (E ) of 20% EFA is about 33.34 kJ mol−1, lower than that of the blank electrolyte (55.58 kJ mol−1), indicating a high temperature independence.

As shown in Fig. 6e, f and Supplementary Fig. 20a, b, the zinc negative electrode in the 20% EFA electrolyte exhibits high reversibility at low temperatures. The cell demonstrates a long zinc plating/stripping life over 13,000 h at −30 °C and 0.1 mA cm−2, 0.1 mAh cm−2, along with a lifetime of 6692 h even at −40 °C. Supplementary Fig. 20c–e presents the practical applications-relevant zinc plating/stripping behavior of symmetric cells under higher current density and low-temperature. At −30 °C, the cell maintains stable operation for over 1600 h and 220 h at 0.5 mA cm−2, 0.5 mAh cm−2, and 1.0 mA cm−2, 1.0 mAh cm−2, respectively. Even at −40 °C, the cell delivered a stable cyclability for nearly 100 h under 0.5 mA cm−2, 0.5 mAh cm−2. Moreover, the Zn||Cu cell achieved an average CE of 99.6% over 300 cycles at −40 °C (0.1 mA cm−2, 0.1 mAh cm−2). This highly stable CE, combined with the long stripping/plating life of Zn||Zn symmetric cells, collectively demonstrates that our electrolyte enables improved reversibility of zinc plating/stripping even under low-temperature conditions.

To evaluate the temperature adaptability of hybrid electrolytes, the performance of Zn||VO @VO cells in 20% EFA is tested at various temperatures. The full cell exhibited average discharge capacities of approximately 338.81, 230.10, 180.98, 120.90, and 89.77 mAh g−1 at 25, −10, −20, −30, and −40 °C, respectively. Upon returning to 25 °C, the capacity recovered to 317.77 mAh g−1 at 0.2 A g−1. More significantly, even at −40 °C, the Zn||VO @VO delivers a long cycling life over 3500 cycles along with almost no capacity degradation at 0.2 A g−1. The comparison between this work and reported similar literature is shown in Fig. 6i and Supplementary Table 3. The phase transformation of VO @VO after cycling at −40 °C was verified by ex-situ XRD measurement. When the potential of the positive electrode reaches low voltage, a diffraction peak located at 12.6° has been observed, which can be ascribed to the formation of Zn (OH) V O·2HO (ZVO). However, the peak of ZVO gradually disappears during the charging process, demonstrating a reversible transformation. This result can be attributed to Emim⁺ absorption on the VO @VO surface, ensuring high positive electrode stability during prolonged cycling. To further verify the practical application of 20% EFA at low temperatures, the performance of the pouch cell at −30 °C was tested. It exhibits an initial capacity of 191.34 mAh g−1 and maintains stable operation over cycling at 0.1 A g−1. The above analysis demonstrates this hybrid electrolyte’s effectiveness in low-temperature applications.

Methods
Electrolyte preparation
A 2 mol L−1 blank electrolyte was prepared by dissolving zinc trifluoromethanesulfonate (Zn(OTf) , 98%, Bide Pharm Co., Ltd.) in deionized water (HO). Then, mixing 1-ethyl-3-methylimidazolium trifluoroacetate ([Emim][TFA], 98%, Shanghai Titan Scientific Co., Ltd.) with H O in volume ratios of 1:9, 2:8, 3:7, 4:6, 7:3, and 9:1, respectively, to form homogeneous solutions. Zn(OTf) was subsequently added to these solutions, resulting in a series of electrolytes, each with a concentration of 2 mol L−1. These were denoted as 10% EFA, 20% EFA, 30% EFA, 40% EFA, 70% EFA, and 90% EFA corresponding to the respective [Emim][TFA] contents. Besides, to verify that a gradient chaotropic anions (rather than a single type) is crucial for optimizing the solvation structure and achieving enhanced performance, substituting EmimTFA with 1-Ethyl-3-methylimidazolium trifluoromethanesulfonate ([Emim][OTf], denoted as ETF, 98%, Shanghai Titan Scientific Co., Ltd.). In addition, the volume ratio of ETF and H O is 2:8.

Preparation of VO @VO positive electrode material
2.4 g V O (99%, Aladdin Scientific Co., Ltd.) and 3.6 g H C O ·2H O (99.5%, Sinopharm Chemical Reagent Co., Ltd.) were dissolved in 75 mL H O and stirred continuously at 70 °C for 2 h, and subsequently transferred into a Teflon-lined autoclave and heated at 180 °C for 10 h. After cooling to 25 °C, the precipitate was collected and washed several times with ethanol and deionized water, followed by drying at 80 °C for 12 h.

Electrode preparation
For the coin cell, a slurry was prepared by mixing VO@VO, acetylene black (99.9%, Canrd Technology Co. Ltd.), and polyvinylidene difluoride (PVDF 5130, Mw about 1100000, Canrd Technology Co. Ltd.) in a weight ratio of 7:2:1, then dispersing the mixture in N-methyl-2-pyrrolidinone (NMP, 99%, Aladdin Scientific Co., Ltd.). This slurry was subsequently uniformly coated onto a titanium (Ti) foil (10 μm in thickness, 99.9%, Tianjin EVS Chemical Technology Co., Ltd.) to form a single-sided coating using a heating-type cast coater (Shenzhen Kejing Star Technology Co., Ltd., MSK-AFA-HC100) and dried at 80 °C for 12 h. The dried electrode was then punched into disks with a diameter of 10 mm using a precision disc cutting machine (Shenzhen Kejing Star Technology Co., Ltd., MSK-T10). The mass loading of VO@VO was maintained at 1.0 mg cm−2. For the pouch cell, the same slurry was applied onto a Ti foil (4 cm × 4 cm), achieving a higher VO @VO mass loading of 10.0 mg cm−2.

Cell assembly
Symmetric and asymmetric cells were configured in CR2025-type coin cells. The assembly consisted of two working electrodes separated by a single layer of glass fiber filter (Whatman GF/D, 16 mm in diameter, 675 μm in thickness, and an average pore size of 2.7 μm), with a stainless steel spacer (1.0 mm thickness) and a spring-loaded plunger (stainless steel, 1.5 kN constant force) completing the stack. In the Zn||Zn cell, two pieces of zinc foil with a diameter of 12 mm (100 μm thickness, 99.9%, Haoxuan Metal Materials Co., Ltd.) are used as electrodes. A volume of 90 μL of electrolyte was injected into each cell. For Zn||Cu or Zn||Ti cells, Cu foil (a diameter of 12 mm, 40 μm thickness, 99.9%, Sinopharm Chemical Reagent Co., Ltd.) or Ti foil (a diameter of 12 mm, 10 μm in thickness, 99.9%, Tianjin EVS Chemical Technology Co., Ltd.) was used to replace one side of the zinc foil. For Zn||VO @VO full cell, the zinc foil is the negative electrode, VO @VO as the positive electrode, and the volume of electrolyte is 100 μL. The pouch cell was assembled by stacking one piece of zinc foil (a thickness of approximately 13 μm, 99.9%, Haoxuan Metal Materials Co., Ltd.) and one piece of single-sided coated positive electrodes (mass loading of 10.0 mg cm−2) with a glass fiber filter (OLEGEEINO GF/A, 280 μm in thickness and an average pore size of 1.63 μm). The stacked assembly was vacuum-sealed in an aluminum-laminated pouch bag, leaving one port open for electrolyte injection. A volume of about 0.6 mL of electrolyte was injected through the open port, then fully sealed under vacuum. The cells were then rested for 12 h to ensure sufficient wetting. During cycling, an external pressure of 1.0 MPa was applied to the pouch cells using a fixture plate.

Electrochemical characterizations
Electrochemical charge/discharge tests were carried out on the Neware battery testing system (NEWARE, Shenzhen, China). The assembled pouch cells and coin cells were activated to 3 formation cycles at 0.5 A g−1 in the voltage range of 0.2~1.6 V, before proceeding to the long-term cycling tests. All electrochemical cycling tests were carried out in a climate chamber (Shenzhen Kejing Star Technology Co. Ltd., MSK-TE906-100P-70-5).
CE data for the Zn||Cu cell were obtained using a battery tester (LAND CT2000A), with a cut-off voltage set as 0.5 V. LSV was conducted for the Zn||Ti cell at a scan rate of 1 mV s−1 and the voltage window from 4.0 to −1.0 V, while the Tafel plot was measured using a Zn||Zn symmetric cell, both performed on the Autolab electrochemical workstation (PGSTAT302N). The ionic conductivity (σ) and desolvation activation energy (Eₐ) of the electrolytes were evaluated via EIS using an Autolab PGSTA T302N electrochemical workstation. Measurements were carried out in potentiostatic mode with a sinusoidal amplitude of 10 mV. The frequency range was scanned from 105 Hz to 10−2 Hz, with 10 data points collected per frequency decade. Before each measurement, the cell was stabilized at the open-circuit potential (OCP) for at least 2 h until the voltage change was less than 1 mV per minute. The test of ionic conductivity was fabricated in asymmetric configuration comprising two stainless steel spacers, a glass fiber separator, and the electrolyte and calculated according to the following formula:

σ= L / (R * A) (1)

where L (cm) is the thickness; A (cm−2) is the electrode contact area, and R is the bulk resistance value. The Zn||Zn cell was used to perform the E , the calculation based on the Arrhenius equation:

1 / R = A e ( − E a / R T ) (2)

Where R denotes the charge transfer resistance, A is the pre-exponential constant, T is the absolute temperature, and R is the standard gas constant.
Cyclic voltammetry (CV) data and DRT were tested on the Autolab workstation (PGSTAT302N). DRT were calculated from the EIS results in conjunction with the DRT-TOOLS toolbox, developed by Professor Francesco Ciucci’s research group. The toolbox is freely available under the GNU license and can be accessed at: https://sites.google.com/site/drttools/.

Preparation and characterization of the ex-situ samples
To investigate the electrode surface chemistry after cycling, the cells were disassembled in an air atmosphere. The cycled electrodes were carefully harvested and rinsed three times with H O to remove residual electrolyte salts. Subsequently, the samples were dried under vacuum at 60 °C for 2 h. The dried electrode samples were then transferred from the vacuum oven to the instrument using a dedicated airtight transfer vessel. All characterization test analysis was conducted at a constant temperature of 25 ± 1 °C.

Material characterizations
Material were characterized: Fourier Transform Infrared (FTIR) spectra were achieved on a Thermo Fisher Nicolet Antaris II spectrometer over the range of 4000–500 cm−1 (zinc selenide (ZnSe) trapezoid prism serving as the reflective element for in situ measurements); Raman spectroscopy was conducted using a HORIBA LabRAM HR Evolution system equipped with a 532 nm laser; NMR spectra were recorded on a Bruker AVII-600 MHz instrument; XRD data were collected via a D8 ADVANCE diffractometer (Bruker AXS); Morphological analysis was carried out using a Tescan MAIA3 XMU field-emission SEM; The composition of the solid electrolyte interface (SEI) was examined via high-resolution transmission electron microscopy (HRTEM, JEOL F200). The phase transition temperature (T) of the samples was determined by differential scanning calorimetry (DSC) on a Mettler Toledo DSC3+ instrument. Chemical states were probed by XPS on a Thermo Fisher K-Alpha spectrometer using Al Kα radiation (1486.6 eV). Time-of-flight secondary ion mass spectrometry (TOF-SIMS) was conducted on a PHI nanoTOF II system (ULVAC-PHI, Japan) with a 30 keV Bi+ primary ion source. Data acquisition covered rectangular regions of 400×400 μm. The Ar⁺ sputtering rate, calibrated against a SO standard, was 0.83±0.05 nm/s under consistent operational conditions. Gas chromatography (Ceaulight, GC-7920) was used to monitor gas production during the zinc plating/stripping process in electrolytes. The direct current to direct current (DC-DC) converter has dimensions of 25×18 mm, with an input voltage range of 0.9 V–5 V, an output voltage of 5 V, and an output current of 600 mA. The X-ray absorption spectra (XAS) were explored by EasyXAFS300+ and analyzed using the ATHENA software package. SAXS and 2D grazing incidence wide-angle X-ray scattering (2D GIWAXS) data were collected on Xenocs Xeuss 2.0. and Xenocs Xeuss 2.0. respectively.

Density functional theory (DFT) computations
The Vienna Ab initio Simulation Package was employed to compute the adsorption and binding energies. Within this framework, electron interactions for both core and valence states were treated using the projector augmented wave approach. The exchange-correlation effects were accounted for by the Perdew–Burke–Ernzerhof functional. A plane-wave basis set with a kinetic energy cutoff of 500 eV was used to expand the wavefunctions, and Brillouin zone integration was performed at the k-point. The binding energy between Zn2+ and various solvents and ions (adsorption energy between zinc surface and various solvents and ions) was determined using the following equation:

E=E(a-b) - E(a) - E(b) (3)

where E(a-b), E(a), and E(b) are the total electronic energies of Zn2+ binds with a solvent molecule or ions (solvent molecule or ions absorb on the zinc surface), Zn2+ (zinc surface), and solvent molecule or ions, respectively. The calculation parameters and the corresponding initial and final configurations are in Supplementary Data 5–16.
All relevant molecular models were structurally optimized in the Gaussian software and were performed at the DFT level using the B3LYP function combined with the 6–311G(d,p) basis set. Subsequent electronic structure analysis, including Electrostatic Potential (ESP) mapping and Frontier Molecular Orbital calculations, was executed on the optimized geometries utilizing the Multiwfn program. Visualization of molecular structures, electron density isosurfaces, and ESP results was facilitated by the VMD software package. The calculation parameters and the corresponding initial and final configurations are in Supplementary Data 21–26.

Molecular dynamics simulations
All MD simulations in this study were carried out using the open-source software GROMACS 2020.6. The MD simulations were performed in 2 M Zn(OTf) electrolytes, both with and without EFA co-solvents. In the initial stages of the simulation, the steepest descent algorithm was utilized to reduce the total energy of the system and avoid excessively short interatomic distances in the starting configuration. Following this, an NPT ensemble was used for 10 ns of equilibration, and the leapfrog algorithm was applied with a timestep of 2 fs. Temperature was maintained at 298.15 K using the V-rescale algorithm, which had a relaxation time of 0.1 ps. The total simulation duration was 5 ns, during which the density distributions of all components were analyzed statistically. The calculation parameters and the corresponding initial and final configurations in Supplementary Data 1–4 and Supplementary Data 17–20.

COMSOL simulation
To simulate the spatial variation of the electric field and the corresponding ion concentration at the interface, the current module and the tertiary current distribution module in COMSOL Multiphysics were employed. A simplified battery model was established to account for the distinctive properties of the zinc negative electrode and the SEI. In the 2D model, the overall size was set as 8 μm in length and 7 μm in width, with a semicircular protrusion at the bottom representing the interface and a radius of 0.5 μm. Smaller circles within this structure represent the organic and inorganic components, each with a radius of 0.2 μm. For the boundary conditions in the current module, one terminal was assigned a voltage of 0.03 V, while the other terminal was grounded. Within the tertiary current-distribution interface, the concentration of Zn2+ was specified as 2 mol·L–1. A voltage of 0.1 V was applied to the positive electrode, accompanied by an average current density of 10 A m−2, while the negative electrode was held at a constant potential of 0 V.

Peer review rounds
[{"round": 1, "reviewer_comments": {"reviewer_1": "This work provides a novel design strategy for a gradient chaotropic ionic liquid-based aqueous electrolyte (Emim⁺-TFA⁻/OTf⁻-Zn2+-H2O), which can simultaneously fulfill the homogeneous Zn deposition and low-temperature operation. The solvation structure of Zn2+ was reconstructed through the dual anion synergistic dissociation (strong dissociation property of TFA⁻ and the moderate hydrophobicity of OTf⁻), achieving the optimization of low-temperature performance and the interface stability, while avoiding the high viscosity defect of the traditional low eutectic solvents. Most impressively, the Zn||Zn symmetric cells stably cycled over 10,000 h/6,600 h (0.1 mA cm−2) at −30°C and −40°C respectively, fully evidence the robust interfacial deposition kinetics under the extreme low-temperature conditions. Besides, the combined multi-scale simulations (electric field distribution, adsorption energy, and solvation structure) with comprehensive in-situ characterization techniques (Raman monitoring of vanadium dissolution of cathode materials, optical microscopy observation of electrodeposition, gas chromatography quantification of HER, and SEI component analysis through TOF-SIMS) provide the in-depth analysis of Zn2+ solvation chemistry, H-bond networks as well as the formation of a water-deficient and Zn2+ conductive SEI layer. In view of the innovativeness of providing a versatile method for superior Zn2+ solvation chemistry and accelerated interfacial ion transport with anti-freezing properties, as well as the impressive cycling lifespan of the Zn batteries at low temperatures, my overall evaluation of this manuscript is it can be considered for publication in Nature Communications after the major comments mentioned below are well addressed.\n1. The main text states that Emim⁺ preferentially adsorb the Zn (002) plane, but DFT only shows that the adsorption energy of Emim⁺ at Zn (002), the adsorption capability of Emim⁺ on the other two dominant peaks (Zn (100) and Zn (101)) should also be provided to fully illustrate the plane-oriented deposition mechanism.\n2. The Zn foil with a thickness of 100 μm is used in the symmetric cells and full cells measurement, the amount of Zn might be excessive, and the depth of discharge (DOD) in these measurements might be very low. Many important works in the field of aqueous Zn anode batteries present the performance of symmetric cells and full cells under a high DOD condition (DOD > 80%) (Nat Commun 15, 8431 (2024)), therefore, the cell tests under a high DOD condition are advised to be conducted to highlight the superiority of the electrolytes.\n3. The low-temperature attenuation mechanism of the full battery should be clarified: the capacity retention rate at −40℃ is \"almost no attenuation\" (Figure 6h), but the analysis of the cathode structure after low-temperature cycling is not provided in this manuscript (such as XRD verification of the VO₂@VO phase transition after cycling).\n4. The source of interface impedance is ambiguous: Low-temperature EIS (Figure 6d) shows an obvious decrease in activation energy, but seem does not distinguish the contributions of SEI impedance and charge transfer impedance. Besides, the raw data and the fitting result of the EIS test in this manuscript should be provided.\n5. The low-temperature pouch cell tests should be conducted to enhance the demonstration of the practical value of the developed gradient chaotropic ionic liquid-based aqueous electrolyte.\n6. The data of pouch cells is incomplete: In Figure 5f, the capacity of the pouch cell after 500 cycles is 132 mAh g−1, but the initial capacity and the corresponding volumetric energy density are not specified, which should be supplemented to highlight the competitiveness of your developed electrolytes.\n7. The influence of the pH value of the electrolyte on the Zn anode stability was not discussed in the manuscript, which is highly correlated with the HER reactions, thus affecting the interfacial deposition kinetics. The corresponding demonstration is advised to be supplemented.\n8. The Ar+ sputtering rate of the XPS and TOF-SIMS should be provided to speculate the SEI thickness.\n9. RDF and CN analysis through MD simulations can quantify the number of H2O, OTf−, and TFA− participating in the initial solvation layer of Zn2+, but only on the MD simulation may be not reliable enough, electrospray ionization mass spectrometry (ESI-MS) (Angew. Chem. Int. Ed. 2023, 62, e202312373) is advised to conducted to reflect the actual solvation structure difference.", "reviewer_2": "In this manuscript, the authors proposed an electrolyte formulation that circumvents the limitations of conventional ionic liquid-based electrolytes, achieving an excellent electrochemical performance in zinc ion batteries. Based on the Hofmeister series, the gradient chaotropic IL-based aqueous electrolyte demonstrated record-long operational durations reported under such extreme conditions. The work is valuable and innovative. Therefore, I suggest it be minor revised and then published on Nature Communications. Some suggestions are as follows.\n(1) The authors introduce two concepts: \"chaotropic-anion\" and the\" Hofmeister series\", both of which are relatively new in the field of electrolyte designing for zinc ion batteries. For the benefit of readers, it is imperative that the authors provide a more detailed background and explanation of these concepts in the introduction section.\n(2) The authors believe that Emim+ preferentially adsorbs on the zinc surface, reconstructing the electric double layer structure. While the authors use adsorption energy to justify the validity of this conclusion, they specifically selected the (002) crystal plane of zinc metal. However, the XRD pattern of zinc metal provided by the authors show a predominance of the (101) crystal plane. Therefore, it is essential to investigate the adsorption of various molecules on the zinc (101) crystal plane.\n(3) The authors mention that the electrolyte forms a hydrophobic and salt-philic interface, but provides no in-depth characterization. What causes this hydrophobicity? It is imperative to characterize the ion distribution at the interface.\n(4) Based on the conclusions drawn in this paper, solvated zinc ions first shed their water molecules during the desolvation process, followed by anions accompanying the zinc ions to the interface. It is crucial to investigate the preferential redox behavior of anions coordinated to zinc ions.\n(5) The authors report impressive battery performance at -40°C. Coulombic efficiency data is indispensable to complete the assessment of Zn anode behavior at this temperature, as it directly quantifies the reversibility of the Zn plating/stripping processes. This data should be added to the article.\n(6) Certain details need to be supplemented, such as the specifics of the molecular electrostatic potential calculations.", "reviewer_3": "In this work, the authors incorporate the ionic liquid EMIMTFA into a zinc-based aqueous electrolyte and systematically optimize its concentration, identifying 20% as the optimal dosage. The study provides a detailed discussion of how EMIMTFA suppresses side reactions at the anode, facilitates uniform zinc deposition, mitigates cathode dissolution, and enhances low-temperature electrochemical performance. While the experimental characterization is thorough, the interpretations are well-supported, and the overall workload is substantial, the originality of the work remains limited. The manuscript emphasizes three points: “Firstly, the associated interactions between these ions are weakened, due to the significant volume difference between the cations and anions of the Zn(OTf)2-H2O-EFA system. Secondly, the independently dispersed Emim+ possesses the positively charged imidazole ring that prefers to absorb on the surface of the Zn anode, which is conducive to decreasing the free H2O molecules in the inner Helmholtz plane (IHP). Attributed to the spontaneous electrostatic reaction, the positively charged IHP promotes the accumulation of anions within the EDL, forming an anion-derived SEI in the subsequent cycle. Thirdly, the TFA⁻ anions from Emim-based ILs and the OTf⁻ anions from zinc salts are relatively inert and are positioned adjacent in the Hofmeister series. As a prototypical chaotropic anion, TFA⁻ disrupts the H-bonding network and modulates the molecular organization of H2O, resulting in increased structural disorder and markedly lowering the freezing point of the whole electrolyte.” However, all three of these mechanisms have been well-documented in the existing literature. In particular, the third point—the disruption of hydrogen bonding and water structuring by highly concentrated or chaotropic additives—is a widely recognized phenomenon and common to many electrolyte systems incorporating high concentrations of ionic liquid additives. From this perspective, the current work appears to largely reiterate established principles without offering substantial conceptual or mechanistic novelty.\nConsequently, I find it difficult to support the publication of a study that primarily relies on changing the additive species without introducing deeper mechanistic insights or truly novel strategies, especially when the resulting observations align closely with previously reported behaviors. Other concerns are listed below.\n1. The proposed gradient in chaotropic strength—from the bulk electrolyte to the electrode interface (inner Helmholtz plane, IHP), characterized by the progressive disruption of the hydrogen-bond network of water molecules—is not directly supported by experimental measurements or spatially resolved computational evidence.\n2. It is recommended to provide additional data for higher (or varied) concentrations in Supplementary Fig. 3 to better illustrate the effect of electrolyte composition.\n3. In the low-temperature performance evaluation (e.g., at −30 °C and −40 °C), the current density and areal capacity were both set at 0.1 mA cm−2 and 0.1 mAh cm−2, respectively, which are too small for the practical application. The authors are suggested to perform higher values such as 1 mA cm−2 and 1 mAh cm−2.\n4. In Figure S11 (b)’s legend, “3M ZnOTF” should be corrected to “3M Zn(OTF)2” for accuracy."}, "author_response": "Responses to Reviewer 1\nReviewer 1: This work provides a novel design strategy for a gradient chaotropic ionic\nliquid-based aqueous electrolyte (Emim⁺-TFA⁻/OTf⁻-Zn2+-H O), which can\n2\nsimultaneously fulfill the homogeneous Zn deposition and low-temperature operation.\nThe solvation structure of Zn2+ was reconstructed through the dual anion synergistic\ndissociation (strong dissociation property of TFA⁻ and the moderate hydrophobicity of\nOTf⁻), achieving the optimization of low-temperature performance and the interface\nstability, while avoiding the high viscosity defect of the traditional low eutectic solvents.\nMost impressively, the Zn||Zn symmetric cells stably cycled over 10,000 h/6,600 h (0.1\nmA cm−2) at −30°C and −40°C respectively, fully evidence the robust interfacial\ndeposition kinetics under the extreme low-temperature conditions. Besides, the\ncombined multi-scale simulations (electric field distribution, adsorption energy, and\nsolvation structure) with comprehensive in-situ characterization techniques (Raman\nmonitoring of vanadium dissolution of cathode materials, optical microscopy\nobservation of electrodeposition, gas chromatography quantification of HER, and SEI\ncomponent analysis through TOF-SIMS) provide the in-depth analysis of Zn2+\nsolvation chemistry, H-bond networks as well as the formation of a water-deficient and\nZn2+ conductive SEI layer. In view of the innovativeness of providing a versatile\nmethod for superior Zn2+ solvation chemistry and accelerated interfacial ion transport\nwith anti-freezing properties, as well as the impressive cycling lifespan of the Zn\nbatteries at low temperatures, my overall evaluation of this manuscript is it can be\nconsidered for publication in Nature Communications after the major comments\nmentioned below are well addressed.\nAuthor response: We greatly appreciate the reviewer’s positive comments on our\nwork. These comments are very helpful for us to improve our manuscript.\n1. Reviewer comment: The main text states that Emim⁺ preferentially adsorb the Zn\n(002) plane, but DFT only shows that the adsorption energy of Emim⁺ at Zn (002),\nthe adsorption capability of Emim⁺ on the other two dominant peaks (Zn (100) and\nZn (101)) should also be provided to fully illustrate the plane-oriented deposition\nmechanism.\nAuthor response: We thank the reviewer for this critical and insightful suggestion. In\nresponse to this valuable suggestion, we have now performed additional DFT\ncalculations to evaluate the adsorption energy of the Emim⁺, H O, TFA, and OTf on\n2\nthe Zn (002), Zn (100), and Zn (101) surfaces, respectively. As shown in\nSupplementary Fig. 1, compared with the Zn (100) and Zn (101) planes, a stronger\nadsorption energy exists between Emim⁺ and the Zn (002) plane. The preferential\nadsorption of Emim+ on the (002) crystal planes, thereby reducing the growth rate of\nthis plane and resulting in the final exposure of (002)-oriented texture. Our subsequent\nSEM and XRD characterizations strongly corroborate this computational conclusion.\nBesides, to further confirm the oriented deposition of Zn along the (002) plane, the\ncycled Zn anodes were thoroughly investigated by X-ray diffraction (XRD) texture\nanalysis, complemented by 2D grazing incidence wide-angle X-ray scattering (2D\nGIWAXS) measurements. As depicted in Fig. 2h, i, in blank electrolytes, weak and\ndiffuse Debye-Scherrer rings, which are assigned to the Zn (101), Zn (100), and Zn\n(002) planes, can be observed. However, attractive diffraction rings of Zn (002) were\ndisplayed in 20% EFA electrolytes, indicating an excellent crystalline orientation. This\nconclusion is further supported by the data presented in Fig. 2j, k. In stark contrast to\nthe blank electrolyte, the electrode cycled in the 20% EFA electrolyte exhibits a\npronounced high-intensity region at the center. This unambiguously demonstrates that\nthe addition of EFA promotes a preferentially oriented Zn deposition with the (002)\ncrystal planes.\nSupplementary Fig. 1 | The adsorption energy of H O, TFA, OTf, and Emim+ on the Zn\n2\n(002), Zn (100), and Zn (101) surface. a adsorption energy and b the corresponding structural\nmodels of H O, TFA, OTf, and Emim+ after adsorption on the surface.\npole figures of zinc anode in different electrolytes.\nThe related revision has been added on pages 5 and 11 in the revised manuscript:\nDensity Functional Theory (DFT) calculations were employed to elucidate the\nregulatory effect of EFA on the EDL structure (Supplementary Fig. 1). The results\nreveal that the adsorption energy of Emim+ on the surface of zinc foils significantly\nexceeds that of the anions (TFA and OTf) and H O. This strong interaction ensures\n2\nthe preferential adsorption of Emim+ onto the electrode surface, rather than H O,\n2\nresulting in a marked reduction in interfacial H O content.\nincidence wide-angle X-ray scattering (2D GIWAXS) complemented by XRD texture\nanalysis was used to perform detailed structural characterization. After cycling in the\nblank electrolyte, the anode displays weak and diffuse Debye-Scherrer rings\ncorresponding to the (101), (100), and (002) planes of zinc, suggesting polycrystalline\nand randomly oriented deposition (Fig. 2h, i). However, the anode cycled in the 20%\nEFA shows a sharp and continuous diffraction ring assigned to the (002) plane,\nindicating highly oriented crystallization. These results are further supported by the\n(002) pole figures (Fig. 2j, k). In contrast with the blank electrolyte, the anode cycled\nfrom the 20% EFA electrolyte displays a pronounced high-intensity region at the center.\nThese results further confirm that the EFA will promote the Zn (002) oriented\ndeposition.\nReference\n52. Peng, Z. et al. Water-shielding electric double layer and stable interphase engineering for\ndurable aqueous zinc-ion batteries. Nat. Commun. 16, 4490 (2025).\n2. Reviewer comment: The Zn foil with a thickness of 100 μm is used in the symmetric\ncells and full cells measurement, the amount of Zn might be excessive, and the depth\nof discharge (DOD) in these measurements might be very low. Many important works\nin the field of aqueous Zn anode batteries present the performance of symmetric cells\nand full cells under a high DOD condition (DOD > 80%) (Nat Commun 15, 8431\n(2024)), therefore, the cell tests under a high DOD condition are advised to be\nconducted to highlight the superiority of the electrolytes.\nAuthor response: We sincerely appreciate the reviewer’s insightful suggestion. We\nagree that testing symmetric cells under high DOD is essential for assessing Zn anode\nreversibility under demanding conditions. We followed the methodology described in\nthe suggested references (Nat Commun 15, 8431 (2024)) and performed Zn||Zn\nsymmetric cell cycling tests at a high depth of discharge (DOD). We also cited “Nat\nCommun 15, 8431 (2024)” as the reference 45 in the revised manuscript. The\nsymmetric cells were fabricated using Zn foils with a thickness of 10 μm, and the\ncycling was performed at a constant current density of 1.0 mA cm2, 4.75 mAh cm2,\nwith a high DOD of 81.2%. The observed stability of 20%EFA surpasses 780 h, which\nwas significantly longer than the cells assembled using blank electrolytes (about 20 h).\nThis result provides strong evidence for the superiority of our 20%EFA electrolyte, even\nunder deep cycling conditions relevant to practical battery operation.\nFig. 2 | Assessment of interfacial compatibility with zinc metal. c DOD test.\nThe related revision has been added on page 9 in the revised manuscript:\nTo probe its feasibility under the practical conditions, Zn//Zn symmetric cells were\nsubjected to high depth of discharge (DOD) testing. When the high DOD is increased\nto 81.2%, the symmetrical cell with 20%EFA delivered a stable stripping/plating\nprocess over 780 h, which is significantly longer than that of the cells assembled using\nblank electrolytes (about 20 h) (Fig. 2c).\nReference\n45. Meng, Y. et al. Robust bilayer solid electrolyte interphase for Zn electrode with high utilization\nand efficiency. Nat. Commun. 15, 8431 (2024).\n3. Reviewer comment: The low-temperature attenuation mechanism of the full battery\nshould be clarified: the capacity retention rate at −40℃ is \"almost no attenuation\"\n(Figure 6h), but the analysis of the cathode structure after low-temperature cycling is\nnot provided in this manuscript (such as XRD verification of the VO₂@VO phase\ntransition after cycling).\nAuthor response: We sincerely appreciate your insightful suggestion regarding phase\nevolution analysis of the VO @VO cathode under low-temperature operation. As\n2\nrequested, we have conducted ex-situ XRD measurements on cycled cathodes (40℃,\n0.2 A g1 for the first and second cycles) to systematically investigate their phase\ntransition. The results conclusively demonstrate the exceptional phase stability of\nVO @VO in 20%EFA electrolyte, aligning with its outstanding capacity retention.\n2\nof the charge-discharge potential (40 ℃, 0.2 A g1, the first and second cycles).\nAs shown in Supplementary Fig. 22, upon initial discharge to 0.2V, a new peak is\nlocated around 12.6, which can be indexed as a (001) plane of Zn (OH) V O ·2H O\n3 2 2 7 2\n(ZVO). As the voltage charges to 0.6V, the characteristic peak belonging to ZVO has\nweakened (first cycling). When recharged to 1.6V, the peaks of ZVO completely\ndisappear. In the whole cycling process, the ZVO exhibits a reversible transformation,\nwhich can be attributed to the absorption of Emim+ on the surface of VO @VO.\nInterestingly, in the cycling process, the diffraction peaks at 38.1, 44.3, and 64.4 of\nVO gradually decrease to disappear in the first cycling process and then do not reappear\nin subsequent cycles, suggesting that VO has undergone irreversible phase\ntransformation. However, no new phase appears after the phase transition, and the\ncharacteristic peak of VO remains clear during the phase transformation of the VO\n2\nprocess. This result indicates that VO₂ dominates zinc ion storage after the phase\ntransition.\nThe related revision has been added on page 20 in the revised manuscript:\nThe phase transformation of VO @VO after cycling at 40°C was verified by ex-situ\ndiffraction peak located at 12.6 has been observed, which can be ascribed to the\nformation of Zn (OH) V O ·2H O (ZVO) (Supplementary Fig. 22). However, the\n3 2 2 7 2\npeak of ZVO gradually disappears during the charging process, demonstrating a\nreversible transformation. This could be attributed to Emim⁺ absorption on the\nVO₂@VO surface, ensuring high cathode stability during prolonged cycling.\n4. Reviewer comment: The source of interface impedance is ambiguous: Low-\ntemperature EIS (Figure 6d) shows an obvious decrease in activation energy, but seem\ndoes not distinguish the contributions of SEI impedance and charge transfer impedance.\nBesides, the raw data and the fitting result of the EIS test in this manuscript should be\nprovided.\nAuthor response: We sincerely thank the reviewer for this insightful comment. We\nagree that a clear distinction between R and R is crucial for a comprehensive\nSEI ct\nunderstanding of the interfacial processes in zinc ion battery. We also acknowledge the\nimportance of data transparency. The formation of SEI is important for cell. In the\nZn//Zn symmetric cell configuration, only a single semicircle is observed in the Nyquist\nplot (in this manuscript). This is likely because the SEI layer formed in the aqueous\nelectrolyte is extremely thin, causing its impedance contribution to be negligible and\nindistinguishable from the charge transfer process. To ensure the robustness of our\nfindings, we conducted an extensive review of authoritative literature [Nat. Commun.\n14, 5443 (2023) and Nat. Commun. 16, 4817 (2025).] and performed equivalent circuit\nfitting using the ZView software, which yielded the most appropriate equivalent circuit\nmodel. As shown in Supplementary Fig. 19 c, the R is the impedance of the solution;\nS\nR is the faradic charge transfer resistance. CPE were employed instead of ideal\nct\ncapacitors to account for surface heterogeneity and roughness. Besides, we fully agree\nwith the reviewer on the importance of providing raw data and the fitting result of the\nEIS test. We have provided the raw data and fitting result in the manuscript\n(Supplementary Fig. 19c-e and Supplementary Table 2).\nFig. 6 | Evaluation of antifreeze Zn2⁺ solvation chemistry. d Arrhenius curves and activation\nenergies.\nSupplementary Fig. 19 | The properties of the electrolyte at low temperatures. c The equivalent\ncircuit model. d blank or e 20% EFA electrolyte.\nSupplementary Table 2 | The fitting results corresponding to R .\nct\nTemperature (K) 313 298 263 253 243\nBlank Rct (Ω) 189 579.2 10674 31252 /\n20% EFA Rct (Ω) 354.2 1350 5839 8675 19707\nReference\n68. Wang, W. et al. Regulating interfacial reaction through electrolyte chemistry enables gradient\ninterphase for low-temperature zinc metal batteries. Nat. Commun. 14, 5443 (2023).\n69. Ma, D. et al. An electrochemically driven hybrid interphase enabling stable versatile zinc metal\nelectrodes for aqueous zinc batteries. Nat. Commun. 16, 4817 (2025).\n5. Reviewer comment: The low-temperature pouch cell tests should be conducted to\nenhance the demonstration of the practical value of the developed gradient chaotropic\nionic liquid-based aqueous electrolyte.\nAuthor response: We sincerely appreciate the reviewer's valuable suggestion regarding\npractical validation. In direct response to this comment, we have now fabricated a pouch\ncell (Zn//VO₂@VO) using 20%EFA electrolyte and conducted low-temperature testing.\nThe result demonstrates the exceptional practicality of our electrolyte. At 30 ℃, the\npouch cell exhibits an initial capacity of about 191.34 mAh g1 and a stable cycling life\nover 36 cycles at 0.1 A g1.\nSupplementary Fig. 23| cycling performance of pouch cell at 30 ℃.\nThe related revision has been added on page 20 in the revised manuscript:\nTo further verify the practical application of 20% EFA at low temperatures, the\nperformance of the pouch cell at 30 ℃ was tested. It exhibited an initial capacity of\n191.34 mAh g1 and maintained stable operation over cycling at 0.1 A g1\n(Supplementary Fig. 23).\n6. Reviewer comment: The data of pouch cells is incomplete: In Figure 5f, the capacity\nof the pouch cell after 500 cycles is 132 mAh g−1, but the initial capacity and the\ncorresponding volumetric energy density are not specified, which should be\nsupplemented to highlight the competitiveness of your developed electrolytes.\nAuthor response: We sincerely thank the reviewer for this insightful comment. We\nagree that providing the initial capacity and volumetric energy density is important for\na comprehensive evaluation of the battery performance. Please allow us to explain and\naddress these points below.\n(1) Regarding the initial capacity:\nIn this study, the “initial capacity” refers to the stable capacity achieved after the\nactivation process (typically within the first few cycles), rather than the very first\ncharge/discharge capacity. This is a common practice in zinc-ion battery research\nbecause the activation process is crucial for achieving stable electrochemical\nperformance. The stable initial capacity of our pouch cell is 202.1 mAh g1. We have\nnow clarified this definition in the revised manuscript on Page 17, Line 3, to avoid any\npotential confusion.\nThe related revision has been added on page 18 in the revised manuscript:\nFollowing activation and stabilization, the cell, with a high active mass loading of\napproximately 10.0 mg cm2, delivered a stable capacity of 202.1 mAh g1 and\nmaintained 132 mAh g1 after 500 cycles at 1.0 A g1.\nThe related revision has been added on page 22 in the revised manuscript:\nAll the pouch cells have been activated under low current densities.\n(2) Regarding the volumetric energy density:\nWe regret the omission of the cell volume data in our initial manuscript, which\nprecluded the calculation of the volumetric energy density. As requested by the reviewer,\nwe have now meticulously reassembled a new pouch cell with identical materials and\nmass loading to precisely determine its volume and calculate this critical metric. The\ndetailed parameters of the newly assembled pouch cell are provided below.\nSupplementary Fig. 17 | Charge and discharge curves of pouch cell at 1.0 A g1.\nSupplementary Fig. 18 | The detailed data of the pouch cell.\nSupplementary Table 1 | The parameters of the full cell.\nCathode Anode Separator Without Al-plastic With Al-plastic\nfilm film\nMass (g) 0.3814 0.2599 0.1460 1.3474 2.5145\nSize (cm) 4×5 4×5 4.5×5.2 4.5×5.2 5.5×6\nThickness\n85 13 280 378 556\n(μm)\nCathode capacity is 0.0483 Ah.\nCapacity (Ah)  Discharge voltage (V)\nVolumetric energy density =\n𝑉𝑜𝑙𝑢𝑚𝑒 𝑜𝑓 𝑐𝑒𝑙𝑙 (𝐿)\nVolumetric energy density\n(Without Al-plastic film)\n=\n4.5×5\n0\n.2\n.0\n×\n4\n3\n8\n7\n3\n8\n×\n×\n0\n1\n.5\n0\n3\n−\n3\n3\n2\n×10−4\nWh L1\n=29.1 Wh L1\nVolumetric energy density\n(With Al-plastic film)\n=\n5.5×6\n0\n×\n.0\n5\n4\n5\n8\n6\n3\n×\n×\n1\n0\n0\n.5\n−\n3\n3\n3\n×\n2\n10−4\nWh L1\n=14.0 Wh L1\nCapacity (Ah)  Discharge voltage (V)\nSpecific energy density =\n𝑚𝑎𝑠𝑠 𝑜𝑓 𝑐𝑒𝑙𝑙 (𝑘𝑔)\nSpecific energy density\n(Without Al-plastic film)\n= 0\n1\n.0\n.3\n4\n4\n8\n7\n3\n4\n×\n×\n0\n1\n.5\n0\n3\n−\n3\n3\n=19.1 Wh kg1\nSpecific energy density\n(With Al-plastic film)\n= 0\n2\n.0\n.5\n4\n1\n8\n4\n3\n5\n×\n×\n0\n1\n.5\n0\n3\n−\n3\n3\n=10.2 Wh kg1\nThe related revision has been added on page 18 in the revised manuscript and\nSupporting Information:\nAs shown in Supplementary Fig. 17 and Supplementary Fig. 18, and Supplementary\nTable 1, the pouch cell demonstrated a considerable energy density.\n7. Reviewer comment: The influence of the pH value of the electrolyte on the Zn anode\nstability was not discussed in the manuscript, which is highly correlated with the HER\nreactions, thus affecting the interfacial deposition kinetics. The corresponding\ndemonstration is advised to be supplemented.\nAuthor response: We appreciate the valuable suggestions from the reviewers. We fully\nagree that pH is a fundamental parameter governing the thermodynamics and kinetics\nof the hydrogen evolution reaction (HER) at the zinc/electrolyte interface, which in turn\nprofoundly influences the morphology, reversibility, and overall anode cycling stability\nof Zn deposition. We appreciate the opportunity to elaborate on this crucial aspect and\nhave conducted additional experiments and analyses to address this insightful comment.\nWe adapted from previously published literature [Energy Environ. Sci. 17, 9611-9622\n(2024).], a custom H-type electrolytic cell incorporating an anion-exchange membrane\nseparator was employed for in-situ pH testing. The zinc foil as working electrode (2 cm\n× 2 cm) and the pH meter were positioned adjacent to the electrode surface within the\nH-type electrolytic cell compartment (Supplementary Fig. 12c). A constant current\nreaction was carried out at an electric current density of 5 mA cm2 for 30 minutes, and\nthe pH value was recorded simultaneously.\nAs shown in the Supplementary Fig. 12d, e, within 30 minutes, the pH value of the\nblank electrolyte changed from 4.98 to 5.45. Because the evolution of H will lead to\n2\nan increase in the pH value of the surface of the electrode (2𝐻 𝑂+2𝑒− → 𝐻 ↑\n2 2\n+2𝑂𝐻−). It’s worth noting that the pH value of 20% EFA is 3.97, which may be due to\nthe hydrolysis of TFA will form an acidic electrolyte system [Adv. Funct. Mater. 34,\n2314347 (2024).]. However, due to the formation of the SEI in cycling, the further\nreaction between fresh zinc and the electrolyte was prevented. Thus, a smaller pH (3.97\nto 4.1) could be observed in 20 % EFA. The significant pH increase suggests that the\nbare Zn anode experienced pronounced HER and corrosion reactions. This result\nconfirmed the pH-regulating capability of 20% EFA, thereby reducing byproduct\nformation, inhibiting dendrite growth, and enhancing cell life.\nSupplementary Fig. 12 | The suppression of side reaction. c Schematic diagram of the in-situ pH\nmeasurement device. d the evolution of the PH value and e digital photos of the different electrolytes\nduring the cycling at a current density of 5.0 mA cm2 and a duration is 30 minutes (size of the zinc\nfoil is 2 cm  2 cm).\nThe related revision has been added on page 14 in the revised manuscript:\nMeanwhile, the results of in situ electrochemical Gas Chromatography (EC-GC)\nmeasurement and in situ PH test directly confirm the inhibition effect of H evolution\n2\nby EFA.\nIt’s worth noting that the pH value of 20% EFA is 3.97, which may be due to the\nhydrolysis of TFA. Nonetheless, the in-situ formation of a stable SEI during cycling\neffectively protects the zinc surface, inhibiting further reactions with the electrolyte.\nWithin 30 minutes, the pH value of the blank electrolyte increases significantly, from\n4.98 to 5.45, which is higher than that of the 20% EFA (3.97 to 4.1) (Supplementary\nFig. 12c-e). This much less pH variation and H evolution amount indicate suppressed\nReference\n21. Wen, J. et al. Enhancing Zn-metal anode stability: key effects of electrolyte additives on ion-\nshield-like electrical double layer and stable solid electrolyte interphase. Adv. Funct. Mater. 34,\n2314347 (2024).\n62. Liu, M. et al. Superhydrophobic and robust hetero-metal-polymer hybrid interphase enables\ndeep-cycling zinc metal anodes. Energy Environ. Sci. 17, 9611-9622 (2024).\n8. Reviewer comment: The Ar+ sputtering rate of the XPS and TOF-SIMS should be\nprovided to speculate the SEI thickness.\nAuthor response: Thanks to the reviewers for the insightful comments. We have\nprovided detailed sputtering parameters. For the XPS depth profiling, as stated in the\nmanuscript (the section of “Gradient Chaotropic Zn2+ Electrolyte to Enable\nCompatibility with Zn Metal” and the Fig. 3d), the SEI thickness values were directly\nderived from the sputtered depth (10 nm, 20 nm, 30 nm, Fig.3d) based on the\ninstrument’s integrated thickness calibration. For TOF-SIMS depth profiling, the Ar⁺\nsputtering rate was referenced to SiO and determined to be 0.83 ± 0.05 nm/s under\n2\nidentical conditions.\nThe related revision has been added on page 24 in the revised manuscript:\nTime-of-flight secondary ion mass spectrometry (TOF-SIMS) measurements were\nperformed with a PHI nano TOF Ⅱ TOF-SIMS (ULVAC-PHI, Japan), utilizing a pulsed\n30keV Bi+ primary ion source. The data were collected from 400 m  400 m areas\nalong the length of the rectangular sample. The Ar+ sputtering rate was referenced to\nSiO and determined to be 0.83 ± 0.05 nm/s under identical conditions.\n2\n9. Reviewer comment: RDF and CN analysis through MD simulations can quantify the\nnumber of H2O, OTf−, and TFA− participating in the initial solvation layer of Zn2+, but\nonly on the MD simulation may be not reliable enough, electrospray ionization mass\nspectrometry (ESI-MS) (Angew. Chem. Int. Ed. 2023, 62, e202312373) is advised to\nconducted to reflect the actual solvation structure difference.\nAuthor response: We sincerely appreciate the reviewer’s insightful suggestion to\nstrengthen our solvation structure analysis. We fully agree with that experimental\nvalidation using ESI-MS characterization beyond MD simulations is valuable. We also\ncited “Angew. Chem. Int. Ed. 2023, 62, e202312373” as the reference 6 in the revised\nmanuscript. However, due to the high salt concentration in our electrolyte (2M\nZn(OTf) +20% EFA), it is difficult to conduct ESI-MS characterization. Because\ndamage and signal suppression, this process disrupts the intrinsic solvation structure.\nCritically, removing salts would dissociate the solvation structure of Zn2+, rendering\nthe data unrepresentative of the operational solvation environment. Therefore, we\nemployed X-ray absorption fine structure analysis (XAFS) and small-angle X-ray\nscattering (SAXS) technique as a direct, non-destructive probe of the Zn2+ solvation\nstructures. Besides, we have also added an additional control experiment to elucidate\nthe importance of specific anion effects determined by the Hofmeister series. Both OTf⁻\nand TFA⁻ are classified as chaotropic anions, and they are arranged in a gradient\nsequence in the Hofmeister series. Our initial data indicated that both anions are\ninvolved in the solvation structure in the EFA electrolyte. To rigorously verify that a\ngradient of chaotropic anions (rather than a single type) is crucial for optimizing the\nsolvation structure and achieving superior performance, we substituted 1-Ethyl-3-\nmethylimidazolium trifluoromethanesulfonate ([Emim][OTf], denoted as ETF). This\ncomparison allows us directly demonstrates the advantage of our designed solvation\nstructure of Zn2+, which is composed of gradient chaotropic anions.\nFig. 1 | Mechanistic insight into interfacial structure and Zn2⁺ solvation reconstruction. e Zn\nK-edge XANES spectra, f FT-EXAFS spectra in R space and g and h WT-EXAFS spectra of blank\nand EFA electrolytes. i SAXS of electrolyte.\nSupplementary Fig. 3 | Regulation of solventization and H-bonds. c WT-EXAFS spectra of ETF.\nThe Zn K-edge X-ray absorption near-edge structure (XANES) spectra provide insights\ninto the coordination environment of Zn2+. As expected, the zinc foil, since its valence\nstate is zero, exhibits the lowest near-edge energy (Fig. 1e). The variations in the\nabsorption edge energy among different electrolytes are governed by differences in the\nelectron-donating ability of the solvated species [Nat. Commun. 16, 71 (2025).].\nTherefore, the lower energy of EFA demonstrates that the chaotropic anions (OTf⁻ and\nTFA⁻) donate more electrons to Zn2+, and the existence of more CIP structure [Energy\nEnviron. Sci. 17, 3443-3453 (2024) and Nat. Commun. 16, 6134 (2025).]. The local\ncoordination environment of the Zn2+ solvation shell in different electrolytes was\ninvestigated by Fourier-transformed extended X-ray absorption fine structure (FT-\nEXAFS) spectra. Compared with blank and ETF electrolytes, the lower peak of Zn-O\nindicates a decrease in Zn2+-H O coordination in Zn2+ solvation structure [Nat.\nFurthermore, the splitting peak emerges at 2.16 Å, representing the Zn-F (TFA)\ncoordination, originating from the direct interaction between Zn2+ and the F atoms of\nthe chaotropic anions (Fig. 1f). This provides direct evidence for the successful\nincorporation of chaotropic anions into the inner solvation shell of Zn2+. The results of\nwavelet-transformed extended X-ray absorption fine structure (WT-EXAFS) further\nconfirm this conclusion (Fig. 1g, h, and Supplementary Fig. 3c).\nBesides, the small-angle X-ray scattering (SAXS) further prove the evolution of\nsolvation structure of Zn2+ in various electrolytes. In the blank electrolyte, a broad\nscattering peak at 1.86 Å1, along with a large 2D SAXS scattering ring is observed,\nwhich belongs to the hydrated of Zn2+ and H O (Fig. 1i). With the addition of IL, a\n2\nsignificant shift of this peak to a lower q value and concomitant with a reduction in the\ndiameter of the scattering ring, indicating the formation of a larger solvation nanocluster\n[Energy Environ. Sci. 18, 1489-1501 (2025).]. Critically, compared with ETF, a more\nblurred scattering ring in EFA electrolyte system suggests that gradient chaotropic\nanions (TFA⁻ and OTf⁻) effectively disrupt the primary solvation shell by replacing\nwater molecules, leading to a less ordered and more diffuse solvation structure [Angew.\nChem. Int. Ed. 64, e202502761 (2025).]. These results confirm the difference between\nelectrolytes.\nThe related revision has been added on pages 7 and 8 in the revised manuscript:\nTo evaluate the essential role of gradient chaotropic anions (as opposed to a single\nspecies) in optimizing solvation structure and electrochemical performance, we\nsubstituted EmimTFA with 1-ethyl-3-methylimidazolium trifluoromethanesulfonate\n([Emim][OTf], denoted as ETF) and conducted detailed solvation structural\ncharacterization. As shown in Zn K-edge X-ray absorption near-edge structure\n(XANES) spectra, the lowest absorption edge of zinc foil is due to its zero-valence state\n(Fig. 1e). Solvated species differ in electron-donating ability, and these differences\ndrive the changes in absorption edge energy across electrolytes. Therefore, the lower\nenergy of EFA demonstrates that the chaotropic anions (OTf⁻ and TFA⁻) donate more\nelectrons to Zn2+ and the existence of more contact ion pairs (CIP). The local\ncoordination environment of the Zn2+ solvation shell was investigated by Fourier-\ntransformed extended X-ray absorption fine structure (FT-EXAFS) spectra and\nwavelet-transformed extended X-ray absorption fine structure (WT-EXAFS).\nCompared with the blank and ETF-containing electrolytes, the lower Zn-O peak in\nEFA-containing electrolytes indicates reduced Zn2+-H O coordination in the Zn2+\n2\nsolvation structure (Fig. 1f). Furthermore, a distinct split feature at 2.16 Å is indicative\nof Zn-F (TFA⁻) coordination, originating from direct interactions between Zn2⁺ and the\nF atoms of the chaotropic anions. These results confirm the coordination of chaotropic\nanions and Zn2+. The results of WT-EXAFS further confirm this conclusion (Fig. 1g, h\nand Supplementary Fig. 3c). Small-angle X-ray scattering (SAXS) proves the\nevolution of the solvation structure of Zn2+ in various electrolytes (Fig. 1i). A broad\nscattering peak at 1.86 Å⁻¹ accompanied by an enlarged 2D SAXS scattering ring is\ncharacteristic of a classic aqueous hydration shell in blank electrolytes. In the presence\nof IL, the lower-q peak and the smaller 2D SAXS ring are consistent with an increased\nreal-space correlation length (d=2π/q) and larger solvation nanoclusters. Importantly,\nthe 2D SAXS pattern for the EFA-containing electrolyte exhibits a blurred ring contour,\nin contrast to the ETF system. This distinct difference confirms a more disordered\nsolvation structure, where gradient chaotropic anions of TFA⁻ and OTf⁻ have\nsuccessfully penetrated and replaced H O molecules in the Zn2+ solvation shell.\n6. Chen, K. et al. Correlating the solvating power of solvents with the strength of ion-dipole\ninteraction in electrolytes of lithium-ion batteries. Angew. Chem. Int. Ed. 62, e202312373\n(2023).\n33. Zhang, B. et al. Electrolyte design for reversible zinc metal chemistry. Nat. Commun. 16, 71\n(2025).\n34. Yang, Z. et al. Amphiphilic electrolyte additive as an ion-flow stabilizer enables superb zinc\nmetal batteries. Energy Environ. Sci. 17, 3443-3453 (2024).\n35. Chang, L. et al. High-entropy solvation chemistry towards affordable and practical Ah-level\nzinc metal battery. Nat. Commun. 16, 6134 (2025).\n36. Ren, H. et al. Tailoring water-in-DMSO electrolyte for ultra-stable rechargeable zinc batteries.\nAngew. Chem. Int. Ed. 64, e202423302 (2025).\n37. Li, Q. et al. Designing a bridging solvation structure using recessive solvents for high energy\ndensity aqueous zinc-ion batteries with 88% depth of discharge zinc rechargeability. Energy\nEnviron. Sci. 18, 1489-1501 (2025).\n38. Wang, N. et al. High-entropy deep eutectic solvent achieves ultra-low polarization zinc anode\nchemistry. Angew. Chem. Int. Ed. 64, e202502761 (2025).\nResponses to Reviewer 2\nIn this manuscript, the authors proposed an electrolyte formulation that circumvents the\nlimitations of conventional ionic liquid-based electrolytes, achieving an excellent\nelectrochemical performance in zinc ion batteries. Based on the Hofmeister series, the\ngradient chaotropic IL-based aqueous electrolyte demonstrated record-long operational\ndurations reported under such extreme conditions. The work is valuable and innovative.\nTherefore, I suggest it be minor revised and then published on Nature Communications.\nSome suggestions are as follows.\nAuthor response: We greatly appreciate the reviewer’s positive comments on our work.\nThese comments are very helpful for us to improve our manuscript.\n1. Reviewer comment: The authors introduce two concepts: \"chaotropic-anion\" and\nthe\" Hofmeister series\", both of which are relatively new in the field of electrolyte\ndesigning for zinc ion batteries. For the benefit of readers, it is imperative that the\nauthors provide a more detailed background and explanation of these concepts in the\nintroduction section.\nAuthor response: We thank the reviewer for this constructive suggestion. We agree\nwith the reviewer that providing a more comprehensive background on these concepts\nis crucial for reader accessibility, especially as their application in Zn-ion battery\nelectrolyte design is relatively novel.\nThe related revision has been added on page 3 in the revised manuscript:\nThe Hofmeister series, also known as ion-specific effects, categorizes ions based on\ntheir relative capacity to influence protein solubility in solutions, resulting in a\ncharacteristic ordering. Ions identified as chaotropic anions exhibit a pronounced ability\nto destabilize protein conformation and stability. Moreover, it has been confirmed that\nthey will break the H-bond network formed by H O molecules.\n25. Xiong, T. et al. Design and structure of electrolytes for all-weather aqueous zinc batteries. Adv.\nFunct. Mater. 35, 2421240 (2025).\n26. Qiu, M. et al. Tailoring water structure with high-tetrahedral-entropy for antifreezing\nelectrolytes and energy storage at −80 °C. Nat. Commun. 14, 601 (2023).\n2. Reviewer comment: The authors believe that Emim+ preferentially adsorbs on the\nzinc surface, reconstructing the electric double layer structure. While the authors use\nadsorption energy to justify the validity of this conclusion, they specifically selected\nthe (002) crystal plane of zinc metal. However, the XRD pattern of zinc metal provided\nby the authors show a predominance of the (101) crystal plane. Therefore, it is essential\nto investigate the adsorption of various molecules on the zinc (101) crystal plane.\nAuthor response: We thank the reviewer for this critical and insightful suggestion. In\nresponse to this valuable suggestion, we have performed additional DFT calculations\nto evaluate the adsorption energy of the Emim⁺, H O, TFA, and OTf on the Zn (002),\ncompared with the Zn (100) and Zn (101) planes, a stronger adsorption energy exists\nbetween Emim⁺ and the Zn (002) plane. The preferential adsorption of Emim+ on the\n(002) crystal planes, thereby reducing the growth rate of this plane and resulting in the\nfinal exposure of (002)-oriented texture. Our subsequent SEM and XRD\ncharacterizations strongly corroborate this computational conclusion.\nBesides, to further confirm the oriented deposition of Zn along the (002) plane, the\ncycled Zn anodes were thoroughly investigated by X-ray diffraction (XRD) texture\nanalysis, complemented by 2D grazing incidence wide-angle X-ray scattering (2D\nGIWAXS) measurements. As depicted in Fig. 2h, i, in blank electrolytes, weak and\ndiffuse Debye-Scherrer rings, which are assigned to the Zn (101), Zn (100), and Zn\n(002) planes, can be observed. However, attractive diffraction rings of Zn (002) were\ndisplayed in 20% EFA electrolytes, indicating an excellent crystalline orientation. This\nconclusion is further supported by the data presented in Fig. 2j, k. In stark contrast to\nthe blank electrolyte, the electrode cycled in the 20% EFA electrolyte exhibits a\npronounced high-intensity region at the center. This unambiguously demonstrates that\nthe addition of EFA promotes a preferentially oriented Zn deposition with the (002)\ncrystal planes.\nSupplementary Fig. 1 | The adsorption energy of H O, TFA, OTf, and Emim+ on the Zn\n2\n(002), Zn (100), and Zn (101) surface. a adsorption energy and b the corresponding structural\nmodels of H O, TFA, OTf, and Emim+ after adsorption on the surface.\npole figures of zinc anode in different electrolytes.\nThe related revision has been added on pages 5 and 11 in the revised manuscript:\nDensity Functional Theory (DFT) calculations were employed to elucidate the\nregulatory effect of EFA on the EDL structure (Supplementary Fig. 1). The results\nreveal that the adsorption energy of Emim+ on the surface of zinc foils significantly\nexceeds that of the anions (TFA and OTf) and H O. This strong interaction ensures\n2\nthe preferential adsorption of Emim+ onto the electrode surface rather than H O,\n2\nresulting in a marked reduction in interfacial H O content.\nincidence wide-angle X-ray scattering (2D GIWAXS) complemented by XRD texture\nanalysis was used to perform detailed structural characterization. After cycling in the\nblank electrolyte, the anode displays weak and diffuse Debye-Scherrer rings\ncorresponding to the (101), (100), and (002) planes of zinc, suggesting polycrystalline\nand randomly oriented deposition (Fig. 2h, i). However, the anode cycled in the 20%\nEFA shows a sharp and continuous diffraction ring assigned to the (002) plane,\nindicating highly oriented crystallization. These results are further supported by the\n(002) pole figures (Fig. 2j, k). In contrast with the blank electrolyte, the anode cycled\nfrom the 20% EFA electrolyte displays a pronounced high-intensity region at the center.\nThese results further confirm that the EFA will promote the Zn (002) oriented\ndeposition.\nReference\n52. Peng, Z. et al. Water-shielding electric double layer and stable interphase engineering for\ndurable aqueous zinc-ion batteries. Nat. Commun. 16, 4490 (2025).\n3. Reviewer comment: The authors mention that the electrolyte forms a hydrophobic\nand salt-philic interface, but provide no in-depth characterization. What causes this\nhydrophobicity? It is imperative to characterize the ion distribution at the interface.\nAuthor response: We appreciate the reviewer's request for a deeper mechanistic\nunderstanding of the hydrophobic and salt-philic interface. We agree that providing\ndirect characterization evidence strengthens this claim. To probe the interfacial ion\ndistribution and hydrophobicity origin, we have performed additional, extensive MD\nsimulations of the electrolyte near the Zn anode surface. We analyzed the density\nprofiles of H O, TFA, OTf, and Emim+ perpendicular to the Zn surface. The classical\n2\nmolecular dynamics (MD) simulation analysis (Supplementary Fig. 2b-e) shows that,\ncompared with the blank electrolyte, a significant reduction of H O molecules within\n2\nthe first ~5-10 Å from the Zn surface in the EFA-containing electrolyte. This depletion\nis attributed to the strong adsorption of Emim+ cations (which have hydrophobic alkyl\nchains) and the chaotropic anions, displacing water from the immediate interface. This\nresult directly proves the formation of the hydrophobic and salt-philic interface in the\nmodified electrolyte.\nSupplementary Fig. 2 | The Reconstruction of EDL and Zn²⁺ solvation by EFA. b Zn/blank and\nd Zn/EFA. Density distribution of H O and ions at the interfaces of c Zn/blank and e Zn/EFA.\nClassical molecular dynamics (MD) simulation displays the distribution of ions and\nmolecules near the zinc anode surface. The abundant H O molecules aggregate within\n2\nthe first ~5-10 Å from the surface of the zinc anode in the blank electrolyte\n(Supplementary Fig. 2b, c). However, strong adsorption of Emim⁺ via its hydrophobic\nalkyl chains, together with robust ion pairing with chaotropic anions, impedes H O to\n2\naccess the zinc surface, thereby reducing interfacial H O and producing a hydrophobic,\n2\nsalt-philic interface (Supplementary Fig. 2d, e).\n4. Reviewer comment: Based on the conclusions drawn in this paper, solvated zinc ions\nfirst shed their water molecules during the desolvation process, followed by anions\naccompanying the zinc ions to the interface. It is crucial to investigate the preferential\nredox behavior of anions coordinated to zinc ions.\nAuthor response: Thank you for the reviewers' rigorous scientific attitude and\nprofessional suggestions. Since zinc ions are consistently accompanied by the\ndesolvation of solvents and anions at the interface during the deposition process,\nstudying the redox priority of individual molecules alone is insufficiently rigorous.\nTherefore, based on the reviewers' recommendations, we have supplemented the\nHOMO and LUMO values of zinc coordination compounds through theoretical\ncalculations, which serve as crucial indicators of a molecule's oxidative and reductive\ncapabilities. As shown in Supplementary Fig. 9, compared to individual molecules,\nthe LUMO values of Zn2+-molecules (anions) are significantly lower, indicating\nenhanced reduction after Zn coordination. Although Zn²⁺-H₂O exhibits the highest\nreduction propensity, the strong adsorption of Emim⁺ effectively excludes interfacial\nH₂O, thereby preventing H evolution and corrosion caused by H₂O decomposition. The\nsuggesting that the [Zn2+-OTf]+ complex is more prone to decomposition. This\nprovides a more stringent explanation for the interfacial charge transfer process and SEI\nformation. Detailed discussions on this aspect have been highlighted in blue colour in\nthe revised manuscript. We sincerely appreciate the reviewers' insights, which have\nsignificantly strengthened the mechanistic foundation of our work.\nSupplementary Fig. 9 | LUMO and HOMO energy of Zn2+-H O, [Zn2+-TFA]+ and [Zn2+-OTf]+.\nUsing frontier molecular orbital theory, the stability of various complexes in the\nelectrolyte was investigated. Although Zn2+-H₂O exhibits the highest reduction\npropensity, the strong adsorption of Emim⁺ effectively excludes interfacial H₂O,\nthereby preventing H evolution and corrosion caused by H₂O decomposition. The\n2\nlowest occupied molecular orbital (LUMO) value of [Zn2+-OTf]+ (2.69 eV) is lower\nthan that of [Zn2+-TFA]+ (2.49 eV), suggesting that the [Zn2+-OTf]+ complex is more\nprefer to decomposition (Supplementary Fig. 9).\n5. Reviewer comment: The authors report impressive battery performance at -40°C.\nCoulombic efficiency data is indispensable to complete the assessment of Zn anode\nbehavior at this temperature, as it directly quantifies the reversibility of the Zn\nplating/stripping processes. This data should be added to the article.\nAuthor response: We thank the reviewer for this constructive suggestion. We fully\nagree with the reviewer that Coulombic Efficiency (CE) is a critical metric for\nquantifying the reversibility of Zn plating/stripping, especially under harsh conditions\nlike 40°C. We have performed CE measurements at 40°C (Zn//Cu cells,\nplating/stripping at 0.1 mA cm2, 0.1 mAh cm2). The CE measurements\n(Supplementary Fig. 21) demonstrate excellent reversibility of cells at low\ntemperatures. The average CE over 300 cycles at 40°C is 99.6%. This high and stable\nCE directly confirms the exceptional reversibility of Zn plating/stripping enabled by\nour electrolyte, even at extremely low temperatures.\nThe related revision has been added on page 19 in the revised manuscript:\nSupplementary Fig. 21 | CE of Zn//Cu cell at 40°C.\nMoreover, the Zn//Cu cell achieved an average Coulombic efficiency of 99.6% over\n300 cycles at −40 °C. This highly stable CE, combined with the ultralong life Zn//Zn\nsymmetric cells, collectively demonstrates that our electrolyte enables superior\nreversibility of zinc plating/stripping even under extremely low-temperature conditions\n(Supplementary Fig. 21).\n6. Reviewer comment: Certain details need to be supplemented, such as the specifics\nof the molecular electrostatic potential calculations.\nAuthor response: We sincerely appreciate the reviewer's insightful feedback regarding\nthe computational details of the molecular electrostatic potential calculations. In the\nrevised manuscript, we have included comprehensive computational details in the\nSupporting Information, specifically in the computational methods section.\nThe related revision in the revised manuscript:\nAll relevant molecular models were structurally optimized in the Gaussian software and\nwere performed at the DFT level using the B3LYP function combined with the 6-\n311G(d,p) basis set. Subsequent electronic structure analysis, including Electrostatic\nPotential (ESP) mapping and Frontier Molecular Orbital calculations, was executed on\nthe optimized geometries utilizing the Multiwfn program. Visualization of molecular\nstructures, electron density isosurfaces, and ESP results was facilitated by the VMD\nsoftware package.\nResponses to Reviewer 3\nIn this work, the authors incorporate the ionic liquid EMIMTFA into a zinc-based\naqueous electrolyte and systematically optimize its concentration, identifying 20% as\nthe optimal dosage. The study provides a detailed discussion of how EMIMTFA\nsuppresses side reactions at the anode, facilitates uniform zinc deposition, mitigates\ncathode dissolution, and enhances low-temperature electrochemical performance.\nWhile the experimental characterization is thorough, the interpretations are well-\nsupported, and the overall workload is substantial, the originality of the work remains\nlimited. The manuscript emphasizes three points: “Firstly, the associated interactions\nbetween these ions are weakened, due to the significant volume difference between the\ncations and anions of the Zn(OTf) -H O-EFA system. Secondly, the independently\n2 2\ndispersed Emim+ possesses the positively charged imidazole ring that prefers to absorb\non the surface of the Zn anode, which is conducive to decreasing the free H O molecules\n2\nin the inner Helmholtz plane (IHP). Attributed to the spontaneous electrostatic reaction,\nthe positively charged IHP promotes the accumulation of anions within the EDL,\nforming an anion-derived SEI in the subsequent cycle. Thirdly, the TFA⁻ anions from\nEmim-based ILs and the OTf⁻ anions from zinc salts are relatively inert and are\npositioned adjacent in the Hofmeister series. As a prototypical chaotropic anion, TFA⁻\ndisrupts the H-bonding network and modulates the molecular organization of H O,\n2\nresulting in increased structural disorder and markedly lowering the freezing point of\nthe whole electrolyte.” However, all three of these mechanisms have been well-\ndocumented in the existing literature. In particular, the third point—the disruption of\nhydrogen bonding and water structuring by highly concentrated or chaotropic\nadditives—is a widely recognized phenomenon and common to many electrolyte\nsystems incorporating high concentrations of ionic liquid additives. From this\nperspective, the current work appears to largely reiterate established principles without\noffering substantial conceptual or mechanistic novelty.\nConsequently, I find it difficult to support the publication of a study that primarily relies\non changing the additive species without introducing deeper mechanistic insights or\ntruly novel strategies, especially when the resulting observations align closely with\npreviously reported behaviors. Other concerns are listed below.\nAuthor response: We sincerely thank the reviewer for providing their comments. We\ntruly appreciate the reviewer's deep knowledge of the existing literatures in the\nelectrolyte field, as demonstrated by their feedback. We fully agree with the reviewer's\npoint of view that the working mechanisms, such as cation-anion interactions, cation\nadsorption inducing anion-derived SEI, and chaotropic anions disrupting the H O\n2\nnetwork, have been reported in various electrolyte systems. However, we believe the\nfundamental novelty and contribution of our work are not in the discovery of these\nisolated principles, but in elucidating the synergistic effect of these three distinct\nmechanisms within an optimized electrolyte system to achieve an excellent\nelectrochemical performance for aqueous zinc batteries. Besides, we proposed a\n“Gradient Chaotropic anions” to modulate the Zn2+ electrolyte. We have conducted\nextensive additional computations and characterizations, including classical MD\nsimulations of the zinc interface, X-ray absorption fine structure (XAFS) analysis,\nSmall Angle X-ray Scattering (SAXS), in situ FTIR, and 2D nuclear magnetic\nresonance spectra (2D NMR). Unlike many previous studies that offer only tentative or\nspeculative explanations regarding the working mechanism of additives, our\ninvestigation into the role of EFA in the electrolyte is unequivocal and comprehensive.\nWithin a unique and complex system, we have for the first time clearly revealed,\ndifferentiated, and synergistically validated the cooperative effects of these\nmechanisms. Our work provides a renewed and profound system-level understanding\nof how these factors work in tandem to address multiple challenges (such as solvation\nstructure, Zn deposition kinetics, interfacial stability, and operational temperature range)\nsimultaneously.\nPlease allow us to address your concerns point by point detailed below:\n(1) Constructing a stable interfacial layer.\nIt is undeniable that the mechanism by which cations adsorb onto the surface of the zinc\nsurface and thereby affect the IHP layer has been reported. However, our work has taken\na significant step forward by:\n1. Proposing a causal chain: a clear causal link has been established. The adsorption\nof Emim+ leads to the replacement of H O in the IHP, thereby forming an\n2\nelectrically charged interface, which ultimately results in the preferential\naccumulation of chaotropic anions. The newly supplemented classical MD\nsimulations of the zinc interface clearly reveal the distribution of ions at the\ninterface. Then, a robust, organic outer-inorganic inner SEI was forming\n(evidenced by XPS depth profiling and TOF-SIMS).\n2. Visualization of the dynamic evolution of the interface: We have newly added\nin situ FTIR testing to clearly illustrate the dynamic evolution of the zinc interface\nduring the charging and discharging process. Establishing a strong connection\nbetween excellent performance and interface evolution.\n(2) The first proposal for the regulation of the solvation chemistry of Zn2+ by\ngradient chaotropic anions.\nWe would like to emphasize that the innovative mechanism proposed in our work is\nbased on the gradient chaotropic anions in the Hofmeister series for the synergistic\nmodification of the Zn2+ solvation structure. This is fundamentally distinct from simply\napplying a known concept. To prove that the solvation structure evolution is a result of\nthe cooperative effect of the two chaotropic anions (TFA⁻ and OTf⁻, which are\npositioned in a gradient within the Hofmeister series) and not merely a consequence of\nadding any IL. We designed an important control experiment: substituting EmimTFA\nwith 1-ethyl-3-methylimidazolium trifluoromethanesulfonate ([Emim][OTf], denoted\nas ETF). Furthermore, the XAFS and SAXS techniques clearly demonstrated the\nvariation in the coordination environment of Zn2+ after introducing the gradient\nchaotropic anions.\n(3) On the chaotropic effect disrupting the H-bond network.\nWe agree that the chaotropic effect is a well-known phenomenon. The novelty in our\nargument lies in:\nSynergy with the two kinds of anions. We demonstrate that the chaotropic effect of\nTFA⁻ works synergistically with the OTf⁻ to achieve a breaking of the H O network.\nattributed to the combined effect of the gradient anions.\nIn summary, we respectfully argue that our manuscript does more than “reiterate\nestablished principles”. It integrates these principles into a framework, providing deep\nmechanistic proof for how they operate together in a novel electrolyte system. We have\nrevised the manuscript to more emphatically highlight this synergistic mechanism as\nthe central novel concept, downplaying the presentation of the individual points as\nisolated discoveries. We hope that the revised version meets the requirements of\npublication in Nature Communications. The point-to-point responses to your questions\nare provided as below.\n1. Reviewer comment: The proposed gradient in chaotropic strength—from the bulk\nelectrolyte to the electrode interface (inner Helmholtz plane, IHP), characterized by the\nprogressive disruption of the hydrogen-bond network of water molecules—is not\ndirectly supported by experimental measurements or spatially resolved computational\nevidence.\nAuthor response: Thank the reviewer very much for the valuable comments. The\nreviewer’s suggestion enabled us to significantly enhance the depth of our work. Firstly,\nwe would like to clarify a potential misunderstanding about the content of the\nmanuscript. The innovation that we proposed is not using the gradient chaotropic\nanions to achieve the progressive disruption of the H-bond network of H O molecules\n2\nfrom the bulk electrolyte to the electrode interface. Rather, we propose introducing IL\nas a co-solvent. The anions in these liquids (TFA) and from Zn(OTf) (OTf) are\n2\nclassified as chaotropic anions, and increase progressively according to the Hofmeister\nseries. They collaboratively and comprehensively disrupt the H-bond network of H O\n2\nand reconstruct the solvation structure of the Zn2+. Besides, the stability of the Zn\ninterface has been improved. Therefore, achieving effective regulation from the bulk\nelectrolyte to the interface.\nTo further elucidate this mechanism and verify that the gradient chaotropic anions\n(rather than a single type) are crucial for optimizing the solvation structure and\nachieving excellent performance, we substituted EmimTFA with 1-ethyl-3-\nmethylimidazolium trifluoromethanesulfonate ([Emim][OTf], denoted as ETF).\nAdditionally, we have conducted an extensive series of supplementary experiments\n(including 2D-NMR, XAFS, SAXS, and in situ FTIR) and simulations (classical MD),\nwhich provide convincing evidence to support our conclusion.\nH-bond network and solvation structure reconstruction in bulk electrolyte:\nTo gain insight into how the chaotropic anions reconstruct the H-bond network, thereby\nsuppressing side reactions resulting from active H O and lowering the freezing point of\n2\nthe electrolyte, the 2D 19F-1H heteronuclear Overhauser spectroscopy (HOESY)\ntechnique was employed. In the blank and the ETF electrolyte reveals an interaction\nbetween the OTf⁻ anion and H O molecules is revealed (inside the brown circles).\n(inside the blue circles), which we assign to a correlation between the TFA⁻ and H O.\nstrongly interact with H O and disrupt the H-bond network.\natoms are used to indicate the chemical shift of the nuclei in the NMR spectra.\nFig. 1 | Mechanistic insight into interfacial structure and Zn2+ solvation reconstruction. j-l 2D\n19F-1H HOESY of electrolytes.\nThe related revision has been added on page 8 in the revised manuscript:\nFurthermore, the 2D 19F-1H heteronuclear Overhauser spectroscopy (HOESY) provides\neffective evidence for the breaking of the H-bond network by the gradient chaotropic\nanions (Fig. 1j-l and Supplementary Fig. 3d-g). Compared with the blank and ETF-\ncontaining electrolytes, where only F (OTF⁻)-H (H O) interactions are observed (inside\n2\nthe brown circles), the EFA exhibits a new coupling peak between F (TFA⁻) and H (H O)\n2\n(inside the blue circles), confirming the cooperation of these anions in breaking the H-\nbond network.\nReference\n39. Tang, J. et al. Neighboring alkenyl group participated ether-based electrolyte for wide-\ntemperature lithium metal batteries. Nat. Commun. 16, 7917 (2025).\nThe Zn K-edge X-ray absorption near-edge structure (XANES) spectra provide insights\ninto the coordination environment of Zn2+. As expected, the Zn foil, since its valence\nstate is zero, exhibits the lowest near-edge energy (Fig. 1e). The variations in the\nabsorption edge energy among different electrolytes are governed by differences in the\nelectron-donating ability of the solvated species [Nat. Commun. 16, 71 (2025).].\nTherefore, the lower energy of EFA demonstrates that the chaotropic anions (OTf⁻ and\nTFA⁻) donate more electrons to Zn2+, and the existence of more CIP structure [Energy\nEnviron. Sci. 17, 3443-3453 (2024) and Nat. Commun. 16, 6134 (2025).]. The local\ncoordination environment of the Zn2+ solvation shell in different electrolytes was\ninvestigated by Fourier-transformed extended X-ray absorption fine structure (FT-\nEXAFS) spectra. Compared with blank and ETF electrolytes, the lower peak of Zn-O\nindicates a decrease in Zn2+-H O coordination in Zn2+ solvation structure [Nat.\nFurthermore, the splitting peak emerges at 2.16 Å, representing the Zn-F (TFA)\ncoordination, originating from the direct interaction between Zn²⁺ and the F atoms of\nthe chaotropic anions (Fig. 1f). This provides direct evidence for the successful\nincorporation of chaotropic anions into the inner solvation shell of Zn2+. The results of\nwavelet-transformed extended X-ray absorption fine structure (WT-EXAFS) further\nconfirm this conclusion (Fig. 1g, h, and Supplementary Fig. 3c).\nBesides, the small-angle X-ray scattering (SAXS) further proves the evolution of\nsolvation structure of Zn2+ in various electrolytes. In the blank electrolyte, a broad\nscattering peak at 1.86 Å1, along with a large 2D SAXS scattering ring is observed,\nwhich belongs to the hydrated of Zn2+ and H O (Fig. 1i). With the addition of IL, a\n2\nsignificant shift of this peak to a lower q value and concomitant with a reduction in the\ndiameter of the scattering ring, indicating the formation of a larger solvation nanocluster\n[Energy Environ. Sci. 18, 1489-1501 (2025).]. Critically, compared with ETF, a more\nblurred scattering ring in EFA electrolyte system suggests that gradient chaotropic\nanions (TFA⁻ and OTf⁻) effectively disrupt the primary solvation shell by replacing\nwater molecules, leading to a less ordered and more diffuse solvation structure [Angew.\nChem. Int. Ed. 64, e202502761 (2025).]. These results confirm the difference between\nelectrolytes.\nFig. 1 | Mechanistic insight into interfacial structure and Zn2⁺ solvation reconstruction. e Zn\nK-edge XANES spectra, f FT-EXAFS spectra in R space and g and h WT-EXAFS spectra of blank\nand EFA electrolytes. i SAXS of electrolyte.\nSupplementary Fig. 3 | Regulation of solventization and H-bonds. c WT-EXAFS spectra of ETF.\nThe related revision has been added on pages 7 and 8 in the revised manuscript:\nTo evaluate the essential role of gradient chaotropic anions (as opposed to a single\nspecies) in optimizing solvation structure and electrochemical performance, we\nsubstituted EmimTFA with 1-ethyl-3-methylimidazolium trifluoromethanesulfonate\n([Emim][OTf], denoted as ETF) and conducted detailed solvation structural\ncharacterization. As shown in Zn K-edge X-ray absorption near-edge structure\n(XANES) spectra, the lowest absorption edge of zinc foil is due to its zero-valence state\n(Fig. 1e). Solvated species differ in electron-donating ability, and these differences\ndrive the changes in absorption edge energy across electrolytes. Therefore, the lower\nenergy of EFA demonstrates that the chaotropic anions (OTf⁻ and TFA⁻) donate more\nelectrons to Zn2+ and the existence of more contact ion pairs (CIP). The local\ncoordination environment of the Zn2+ solvation shell was investigated by Fourier-\ntransformed extended X-ray absorption fine structure (FT-EXAFS) spectra and\nwavelet-transformed extended X-ray absorption fine structure (WT-EXAFS).\nCompared with the blank and ETF-containing electrolytes, the lower Zn-O peak in\nEFA-containing electrolytes indicates reduced Zn2+-H O coordination in the Zn2+\n2\nsolvation structure (Fig. 1f). Furthermore, a distinct split feature at 2.16 Å is indicative\nof Zn-F (TFA⁻) coordination, originating from direct interactions between Zn2⁺ and the\nF atoms of the chaotropic anions. These results confirm the coordination of chaotropic\nanions and Zn2+. The results of WT-EXAFS further confirm this conclusion (Fig. 1g, h\nand Supplementary Fig. 3c). Small-angle X-ray scattering (SAXS) proves the\nevolution of the solvation structure of Zn2+ in various electrolytes (Fig. 1i). A broad\nscattering peak at 1.86 Å⁻1 accompanied by an enlarged 2D SAXS scattering ring is\ncharacteristic of a classic aqueous hydration shell in blank electrolytes. In the presence\nof IL, the lower-q peak and the smaller 2D SAXS ring are consistent with an increased\nreal-space correlation length (d=2π/q) and larger solvation nanoclusters. Importantly,\nthe 2D SAXS pattern for the EFA-containing electrolyte exhibits a blurred ring contour,\nin contrast to the ETF system. This distinct difference confirms a more disordered\nsolvation structure, where gradient chaotropic anions of TFA⁻ and OTf⁻ have\nsuccessfully penetrated and replaced H O molecules in the Zn2+ solvation shell.\n6. Chen, K. et al. Correlating the solvating power of solvents with the strength of ion-dipole\ninteraction in electrolytes of lithium-ion batteries. Angew. Chem. Int. Ed. 62, e202312373\n(2023).\n33. Zhang, B. et al. Electrolyte design for reversible zinc metal chemistry. Nat. Commun. 16, 71\n(2025).\n34. Yang, Z. et al. Amphiphilic electrolyte additive as an ion-flow stabilizer enables superb zinc\nmetal batteries. Energy Environ. Sci. 17, 3443-3453 (2024).\n35. Chang, L. et al. High-entropy solvation chemistry towards affordable and practical Ah-level\nzinc metal battery. Nat. Commun. 16, 6134 (2025).\n36. Ren, H. et al. Tailoring water-in-DMSO electrolyte for ultra-stable rechargeable zinc batteries.\nAngew. Chem. Int. Ed. 64, e202423302 (2025).\n37. Li, Q. et al. Designing a bridging solvation structure using recessive solvents for high energy\ndensity aqueous zinc-ion batteries with 88% depth of discharge zinc rechargeability. Energy\nEnviron. Sci. 18, 1489-1501 (2025).\n38. Wang, N. et al. High-entropy deep eutectic solvent achieves ultra-low polarization zinc anode\nchemistry. Angew. Chem. Int. Ed. 64, e202502761 (2025).\nRegulation of the interface:\nAdditionally, we employed classical MD simulations and in situ FTIR tests to elucidate\nthe regulation of EFA on the Zn interface.\nTo probe the interfacial ion distribution and hydrophobicity origin, we have performed\nadditional, extensive MD simulations of the electrolyte near the Zn anode surface. We\nanalyzed the density profiles of H O, TFA, OTf, and Emim+ perpendicular to the Zn\n2\nsurface. The classical molecular dynamics (MD) simulation analysis (Supplementary\nFig. 2) shows that, compared with the blank electrolyte, a significant reduction of H O\n2\nmolecules within the first ~5-10 Å from the Zn surface in the 20% EFA electrolyte. This\ndepletion is attributed to the strong adsorption of Emim+ cations (which have\nhydrophobic alkyl chains) and the chaotropic anions, displacing water from the\nimmediate interface. This result directly proves the formation of the hydrophobic and\nsalt-philic interface in the modified electrolyte.\nSupplementary Fig. 2 | The Reconstruction of EDL and Zn2+ solvation by EFA. b Zn/blank and\nd Zn/EFA. Density distribution of H O and ions at the interfaces of c Zn/blank and e Zn/EFA.\nClassical molecular dynamics (MD) simulation displays the distribution of ions and\nmolecules near the zinc anode surface. The abundant H O molecules aggregate within\n2\nthe first ~5-10 Å from the surface of the zinc anode in the blank electrolyte\n(Supplementary Fig. 2b, c). However, strong adsorption of Emim⁺ via its hydrophobic\nalkyl chains, together with robust ion pairing with chaotropic anions, impedes H O to\n2\nassess the Zn surface, thereby reducing interfacial H O and producing a hydrophobic,\n2\nsalt-philic interface (Supplementary Fig. 2d, e).\nBesides, deciphering the electrode-electrolyte interfacial dynamics during cycling is\nessential to establish causal links between interfacial transformations and performance\ndegradation mechanisms. In-situ FTIR test, which is based on the attenuated total\nreflection (ATR) principle, can be employed to analyze the dynamic interface evolution\nand reveals two distinct stages during Zn2+-electrodeposition. In the In-situ FTIR test,\na zinc selenide (ZnSe) trapezoid prism is used as the reflection element, Ti mesh as the\nworking electrode, Zn foil as the counter and reference electrode, and electrolyte as the\nsample medium (Supplementary Fig. 13). Infrared beam undergoes attenuated total\nreflection (ATR) within the crystal prior to reaching the MCT detector, generating an\nevanescent wave at the crystal. Generally, the evanescent wave further penetrates the\nelectrolyte, and the energy attenuated can reflect the information on the electrolyte,\nsuch as the evolution of ion concentration at the interface over time. Thus, the evolution\nof ion concentration at the interface of the working electrode (Ti mesh) can be collected\nand detected during Zn2+ plating/stripping cycling. Abs. (OCV) is the first spectrum of\nelectrolyte at open circuit voltage (OCV) (before cycling). Abs. (n) is the subsequent\nspectrum in cycling. The A(n)-A(OCV) relative absorbance evolution during charging\nand discharging.\nFor blank electrolyte, a sustained negative drift in relative absorption intensity emerges\n(v(SO ), OTf) during the whole plating/stripping process, which is a characteristic\n3\nmanifestation due to the continuous consumption of OTf at the interface (Fig. 4e).\nNotably, the depletion of the W-H bond (weak H-bond) dominates interfacial\nreconfiguration, with its intensity loss exceeding the combined growth of M-H\n(medium H-bond) and S-H (strong H-bond) species. These results reveal that\nuncontrolled consumption of active H O and OTF⁻ on the surface of the electrode in\n2\nthe blank electrolyte favors severe HER and parasitic side reactions. This dual-pathway\nfailure mechanism fundamentally underlies the observed performance decay of the cell.\nOn the contrary, attributed to the absorption of Emim+ on the electrode, the free H₂O at\nthe electrode interface has been significantly reduced. The conversion of W-H to S-\nH/M-H directly evidences suppressed H evolution (Fig. 4f). Moreover, the reversible\n2\nnegative/positive shifts of the relative absorption intensity (v(SO ), OTf) during\n3\nplating/stripping correspond to interfacial desolvation and resolvation of Zn2+,\nrespectively, reflecting dynamic solvent sheath reorganization at the electrode surface.\nCollectively, these results establish the function of EFA on interfacial regulation:\nsuppressing hydrogen evolution while facilitating the desolvation/resolvation of Zn2+\nions during battery operation.\nSupplementary Fig. 13 | Schematic of electrochemical cell for in situ FTIR measurements.\nFig. 4 | Evaluation of zinc deposition behavior and side reaction suppression. In situ FTIR\npatterns of e blank and f 20% EFA.\nThe related revision in the revised manuscript:\nThe dynamic interface microevolution of the zinc anode during cycling has been\ncharacterized by in situ FTIR (Supplementary Fig. 13). The relative absorption\nintensity of (v(SO ), OTf) shows a sustained negative drift. The consumption of the\nthe fact that uncontrolled consumption of both active H O and OTf⁻ on the surface of\n2\nthe zinc anode promotes severe H evolution and side reactions in the blank electrolyte\n2\nduring cycling, resulting in a rapid decline of the cell’s performance (Fig. 4e). However,\nthe addition of EFA significantly reduces free H O molecules at the electrode interface\n2\ndue to the absorption of Emim⁺. The conversion of W-H to S-H/M-H directly confirms\nthe suppression of H evolution (Fig. 4f). Furthermore, the reversible decrease and\n2\nincrease in the absorption intensity of the v(SO ), OTf during cycling, indicate a\n3\ndynamic and reversible process of desolvation/resolvation.\nReference\n63. Yu, X. et al. Deciphering multi-dimensional interfacial mechanisms via organic cosolvent\nengineering for sustainable zinc metal batteries. Nat. Commun. 16, 3820 (2025).\n64. Yu, X. et al. Unlocking dynamic solvation chemistry and hydrogen evolution mechanism in\naqueous zinc batteries. J. Am. Chem. Soc. 146, 17103-17113 (2024).\n2. Reviewer comment: It is recommended to provide additional data for higher (or\nvaried) concentrations in Supplementary Fig. 3 to better illustrate the effect of\nelectrolyte composition.\nAuthor response: We appreciate the valuable suggestions from the reviewers. We have\nadded the additional data for higher concentrations and discussed it in the manuscript.\nSupplementary Fig. 5 | Cycling performance of Zn//Zn symmetric cells in electrolytes with\ndifferent volume ratios of EFA.\nThe related revision has been added on page 9 in the revised manuscript:\nIn addition, the Zn//Zn cells in 10%, 30%, and 40% EFA electrolyte exhibit stable\ncycling performance of 480 h, 450 h, and 370 h, respectively (Supplementary Fig. 5).\nHowever, increasing the EFA concentrations (such as 70% EFA and 90% EFA) leads to\na sharp decline in cycle life, accompanied by a significant voltage polarization increase,\nwhich may stem from the high viscosity of EFA impeding ion transport.\n3. Reviewer comment: In the low-temperature performance evaluation (e.g., at −30 °C\nand −40 °C), the current density and areal capacity were both set at 0.1 mA cm−2 and\n0.1 mAh cm−2, respectively, which are too small for the practical application. The\nauthors are suggested to perform higher values such as 1 mA cm−2 and 1 mAh cm−2.\nAuthor response: We would like to express our gratitude to the reviewers for their\nvaluable comments on our manuscript. We appreciate their suggestion regarding the\nlow-temperature performance evaluation at 30 °C and 40 °C. We agree that higher\ncurrent densities and areal capacities are more relevant for practical applications.\nTherefore, we have supplemented the cycling performance of the symmetric cells\nassembled with 20%EFA under conditions of 30 °C and 40 °C, with higher current\ndensity and specific capacity. As shown in Supplementary Fig. 20c-e, at 30°C, the\nsymmetric cell can be stable for more than 1600 h and 220 h at 0.5 mA cm2, 0.5 mAh\ncm2, and 1.0 mA cm2, 1.0 mAh cm2, respectively. Even at a temperature of 40°C,\nthe cell can be cycled for nearly 100 h at 0.5 mA cm2, 0.5 mAh cm2. These data\ndemonstrate the practical applicability of the 20% EFA at low temperatures.\nSupplementary Fig. 20 | Electrochemical performance of the cells at low temperatures. Cycling\nlife at low temperature: c 0.5 mA cm2, 0.5 mAh cm2, d 1.0 mA cm2, 1.0 mAh cm2 at 30 ℃; e\n0.5 mA cm2, 0.5 mAh cm2 at 40 ℃.\nThe related revision has been added on page 19 in the revised manuscript:\nSupplementary Fig. 20c-e presents the practical applications-relevant cycling\nperformance of symmetric cells under higher current density and low temperature. At\n−30 °C, the cell maintains stable operation for over 1600 h and 220 h at 0.5 mA cm2,\n0.5 mAh cm2, and 1.0 mA cm2, 1.0 mAh cm2, respectively. Even at −40 °C, the cell\ndelivered a stable cyclability for nearly 100 h under 0.5 mA cm2, 0.5 mAh cm2.\n4. Reviewer comment: In Figure S11 (b)’s legend, “3M ZnOTF” should be corrected\nto “3M Zn(OTF) ” for accuracy.\nhave corrected in Supplementary Fig. S15b.\nSupplementary Fig. 15 | Electrochemical performance of the full cell. b Cycling performance\nof Zn//VO @VO cell in three kinds of electrolytes at 2.0 A g1.\n2"}, {"round": 2, "reviewer_comments": {"reviewer_1": "This reviewer is satisfied with the revisions made by the authors, which strengthen this manuscript substantially. Regarding the satisfied revisions made, this reviewer would like to recommend acceptance of this manuscript for publication in Nature Communications.", "reviewer_2": "It is ready for publicaiton.", "reviewer_3": "The authors have convincingly strengthened their concept of Chaotropic Regulation, particularly in elucidating ionic distributions in both bulk and interfacial regions and the associated in-situ processes. With the extensive new data and careful revisions, the manuscript now demonstrates solid scientific merit. Therefore, I recommend this manuscript for publication."}, "author_response": ""}]

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