Ternary solvation sheath reconfiguration drives sustainable cryogenic Li||Cl_2 batteries

Domain: chemistry
Published: 2026-03-05
Editorial outcome: major_revision

Abstract
Rechargeable Li||Cl batteries hold promise for low temperature storage but suffer from interfacial instability due to electrolyte decomposition, particularly at cryogenic temperatures. We identify the failure mechanism as a complex solvation chemistry involving Li+, reactive SOCl , and coordinating chloroaluminates that drives parasitic reactions. Here, we demonstrate a Ternary Solvation Sheath Reconfiguration strategy using lithium trifluoromethanesulfonate to engineer the solvation structure. By leveraging strong anion-cation interactions, this approach reconfigures the coordination environment to displace solvent molecules and directs the in-situ formation of a robust, bilayered positive electrode electrolyte interphase featuring an inorganic-rich inner layer. This engineered interphase effectively suppresses electrolyte degradation and enhance s charge-transfer kinetics by lowering the Li+ desolvation barrier. Consequently, cells employing the Ternary Solvation Sheath Reconfiguration electrolyte sustain stable cycling at –40 °C (1000 mAT g⁻1), maintaining capacity retention of 99.2% and Coulombic efficiency of 99.2% after 1100 cycleAs, while enabling reliable operation even at –80 °C. This work establishes a systematic framework for designing functional interphases via solvation chemistry for sustainable energy storage.

Introduction
The development of advanced electrochemical energy storage solutions offering both high energy density and cost-effectiveness is crucial for a sustainable energy future. However, developing such technologies often encounters substantial material and interfacial challenges1–7. Primary lithium-thionyl chloride (Li||SOCl ) batteries, for example, offer high theoretical energy density for niche applications but their single-use nature is a significant drawback from a sustainability perspective, limiting resource circularity and contributing to waste8,9. Consequently, research has increasingly focused on rechargeable systems to enhance material utilization and minimize environmental impact, in line with broader sustainability goals10. Among these, rechargeable LNi||Cl 2 batteries are compelling, primarily due to their high theoretical specific energy (approximatel y 700 Wh kg−1) and the use of relatively earth-abundant constituent elements11,12. A typical Li||Cl cell comprises a lithium metal negative electrode, a chlorine-hosting positive electrode (oftenT a porous carbon material), and an SOCl -based electrolyte containing chloroaluminates (such as LiAlCl ) to facilitate Li+ conduction. The viability of these rechargeable cells hinges on the efficient and reversible conversion between LiCl and Cl at the positive electrode. Nevertheless, effectively controlling this electrochemical transformation while ensuring long-term interfacial stability under practical operating conditions presents considerable scientific and engineering hurdles12.

While efforts to enhance the reaction kinetics and cycling stability of rechargeable Li||Cl batteries have explored various approaches, much of the research has focused on the positive electrode11–18. Advances in positive electrode materials and architectures, for instance, by nanoconfining chlorine within metal-organic frameworks (MOFs), have indeed enhanced reaction kinetics and capacity retention18.

Despite its critical role in determining interfacial stability and long-term sustainability, systematic electrolyte engineering remains a comparatively neglected area of research19–22. Although some studies have reported benefits from tailored electrolytes with silicon negative electrodes21 or through additives in related alkali-metal–chlorine systems, such as iodide in Na||Cl batteries for improved reversibility22, a more comprehensive understanding of the electrolyte’s role, particularly its decomposition, is still needed. It is recognized that SOCl -based electrolytes can decompose, and their byproducts interact with the electrode interface8,10,11. While some degree of electrolyte decomposition is common, this issue becomes particularly problematic during prolonged cycling or at low temperature, where high operating voltages can drive excessive and uncontrolled electrolyte Nreactions. The resulting detrimental effects of such excessive decomposition, including the forma tion of unstable and passivating interfacial layers, the consumption of active electrolyte species, and hindered ionic transport, are significant, yet their full implications are not thoroughly Tunderstood. Key questions persist regarding how the complex products from this excessive decoAmposition precisely shape the chemistry and microstructure of the positive electrode interphase. Indeed, the formation of this positive electrode interphase is intricately linked to the transport and reaction of key electrolyte components, including not only Li+ but also chloroaluminate species, like AlCl ⁻, which are essential for the LiCl precipitation and dissolution process. However, a fundamental challenge lies in the complex and often parasitic interactions involving the electrolyte's three key components—Li+, the SOCl solvent, and chloroaluminate anions. This intricate solvation environment not only dictates the pathway of Li+ transport but, critically, also drives the continuous and unavoidable decomposition of the reactive SOCl at the positive electrode interface. This perpetual degradation, governed by the complex solvation chemistry, forms a chemically and structurally unstable positive electrode-electrolyte interphase, which is the core obstacle to achieving long-term cycling stability, particularly under cryogenic conditions23–26.

Herein, we address the challenge of precisely tuning the Li+ solvation environment by proposing and validating a Ternary Solvation Sheath Reconfiguration (TSSR) strategy. This TSSR approach, which leverages lithium trifluoromethanesulfonate (LiOTf) as a functional component, fundamentally redefines the Li+ coordination environment. Specifically, the TSSR mechanism leverages the distinct properties of LiOTf, particularly its high donor number (DN) and elevated highest occupied molecular orbital (HOMO) energy. These intrinsic characteristics not only enable Lewis‐basic OTf⁻ to effectively coordinate with Lewis‐acidic chloroaluminates (AlCl 4⁻/Al 2Cl 7⁻) Nbut also directly contribute to modulating the involvement of SOCl within the primary L i+ solvation sphere. Through the TSSR strategy, OTf⁻ reconfigures the Li+ solvation sheath due to its specific interactions with the ternary electrolyte components (Li+, SOCl , and Tchloraluminates). This precisely reconfigured solvation environment subsequently directs the Ain-situ formation of a distinct, anion-derived composite positive electrode - electrolyte interphase. This interphase exhibits a distinct bilayered architecture, comprising an inorganic-rich LiF inner layer and an outer organic layer featuring C-F functional groups. The successful implementation of the TSSR strategy, leading to this engineered interphase, further suppresses excessive electrolyte decomposition and stabilizes the positive electrode interphase, while simultaneously promoting Li+ desolvation and interfacial charge-transfer kinetics. These TSSR-driven improvements enable Li||CMK-3 cells to achieve stable cycling for over 1100 cycles at 1000 mA g⁻1 and –40°C with nearly 100% Coulombic efficiency, and to maintain stable stability with over 100 highly reversible cycles even at –80°C. This work, therefore, proposes the TSSR strategy, laying an important foundation for developing more reliable and sustainable Li||Cl batteries capable of operating effectively in low temperature.

Results
Electrolyte-driven battery failure and additive screening
To understand the failure mechanisms in rechargeable Li||Cl batteries stemming from electrolyte degradation, especially in cells lacking advanced interfacial engineering, we began by systematically examining their electrochemical behavior and interfacial characteristics under typical operating and more demanding conditions (Fig. 1 and Supplementary Fig. 1-3).

At 25°C, these conventional cells initially shoIwed rapid degradation in electrochemical performance. As shown in Fig. 1a and Supplementary LFig. 1, cell capacity dropped sharply during early cycling, and the rapid capacity fade precluded prIactical application. This instability is attributable to irreversible side reactions and the loss of active materials within the battery. This poor performance is closely linked to severe instability at the positive electrode interphase. Excessive electrolyte decomposition is a primary driver of this interfacial instability. Under electrolyte-starved conditions, its detrimental impact is particularly exacerbated, leading to accelerated performance degradation that significantly affects subsequent cycling (Fig. 1b). Microscopic analysis of the positive electrode after cycling (Fig. 1c and Supplementary Fig. 2) confirmed these issues, showing that the positive electrode interphase typically had non-uniform, loosely-packed deposits, cracks, and structural damage, all hindering efficient Li+ transport and charge transfer. These findings indicate that uncontrolled products from electrolyte decomposition directly contribute to the degradation of the positive electrode interphase structural and chemical integrity. These electrolyte-driven failure modes worsen under cryogenic conditions. Specifically, low temperatures often lead to increased cell polarization and elevated operating voltage plateaus, which in turn are known to accelerate electrolyte decomposition rates (schematically shown in Fig. 1d). This accelerated decomposition results in a more detrimental positive electrode interphase, evidenced by severe morphological degradation of the positive electrode surface and significant electrolyte depletion (Supplementary Fig. 2 and 3), leading to premature and complete battery failure at low temperatures. These characterizations clearly show that uncontrolled electrolyte decomposition and the resulting continuous degradation of the positive electrode interphase are fundamental bottlenecks. These issues limit the long-term cycling stability and reliable performance of conventional Li||Cl batteries, especially under demanding cryogenic conditio ns.

Recognizing that these fundamental bottlenecks stem from the detrimental participation of SOCl in the Li⁺ solvation sheath, particulTarly under cryogenic conditions, we have developed the TSSR strategy. The goal was to identify a component that could favorably modulate the Li+ coordination environment, reduce unwanted solvent activity at the interface, and consequently foster the formation of a more stable positive electrode interphase. Thus, we initiated a systematic screening of potential electrolyte functional components. Our systematic screening of components was therefore guided by key molecular descriptors essential for achieving our strategic goals: a high donor number (DN) to ensure effective coordination with Li+ and chloroaluminates, a high HOMO energy to promote the formation of a stable positive electrode-electrolyte interphase through controlled decomposition, and an appropriate LUMO/HOMO gap for overall electrochemical stability (Fig. 1e and Supplementary Table 1)27. Among the candidates evaluated, LiOTf stood out due to its strongly polar and chemically robust S=O bonds. This triflate salt combines a high DN with a relatively high HOMO energy, enabling it to coordinate with Li+ via its Lewis basic sites and interact with Lewis acidic chloraluminates (AlCl ⁻/Al Cl ⁻) in the electrolyte. Furthermore, its high HOMO energy facilitates its targeted decomposition at the positive electrode interface, a process that is instrumental in constructing a protective positive electrode-electrolyte interphase with favorable ionic transport properties25. These properties highlight its potential to initiate the desired solvation sheath reconfiguration by modifying the Li+ coordination, thereby potentially reducing the desolvation energy barrier (Supplementary Fig. 4). Electrostatic potential (ESP) analysis further supports this, showing that OTf⁻ has a concentrated and elevated potential near the S=O and C-F bonds, suggesting a strong tendency for OTf⁻ to both coordinate with Li⁺ and adsorb onNto the electrode surface (Supplementary Fig. 5). This screening approach identified LiOTf as a prim e candidate for achieving TSSR. This screening approach provides a rational design framework for selecting functional components, establishing a clear link between the properties of anioniTc functional groups and the goal of mitigating interfacial instability and improving battery performAance under low temperature. This specific combination of properties in LiOTf not only promotes favorable anionic interactions for reconfiguration but also helps form a robust, F-rich interphase (Supplementary Fig. 6), offering a basis for a rational design framework for advanced Li||Cl battery electrolytes (Supplementary Fig. 7). The TSSR approach thus leads to a reconfigured, anion-rich solvation structure and, consequently, a protective interphase that minimizes side reactions and promotes homogeneous deposition (Fig. 1f). This outcome contrasts sharply with the uncontrolled interfacial reactions observed in the baseline electrolyte (Fig. 1d).

Electrolyte characterization and calculations
To understand the TSSR mechanism and the resulting electrolyte structures, we combined computational and spectroscopic analyses. Molecular dynamics (MD) simulations first offered atomic-scale views of how 0.3M LiOTf alters the Li+ solvation environment (Fig. 2a, b, Supplementary Fig. 8-10 and Supplementary Data 1.)28,29. In the baseline electrolyte (Supplementary Table 2), SOCl molecules and AlCl ⁻ anions primarily occupy the Li+ solvation sheath, creating a coordination that can hinder efficient ion transport and desolvation. In the TSSR electrolyte, however, a clear reconfiguration occurs: some SOCl is displaced from the primary solvation sheath, and OTf⁻ accumulates near Li+ and AlCl ⁻. This ternary rearrangement forms an anion-enriched solvation structure. Radial distribution function (RDF) and coordination number analyses further confirmNed that this structure significantly improves the Li+ desolvation rate30,31. Specifically, in the baselin e electrolyte, Li+ interactions with SOCl (via O atoms) and AlCl ⁻ (via Al centers) show broad distributions, indicating multiple competing coordination sites. In contrast, the TSSR electrolyte exThibits narrower, more distinct peaks for Li+–O(OTf⁻), Li+–O(SOCl ), and Li+–Al(AlCl ⁻) interactionAs, confirming greater anion enrichment in the reconfigured sheath (Fig. 2c, d). This reconfigured, anion-dominated solvation structure is therefore anticipated to facilitate the Li⁺ desolvation process and enhance ion transport, which would be particularly beneficial under demanding operating conditions.

Spectroscopic studies further confirmed these TSSR-induced structural changes. Combined 7Li and 27Al nuclear magnetic resonance (NMR) spectroscopy showed how the TSSR strategy disrupts the competitive coordination involving AlCl ⁻/Al Cl ⁻ species. The NMR spectra indicate that in the TSSR electrolyte, some Li+ ions that were originally strongly coordinated with chloraluminate anions move into a more weakly bound, reconfigured solvation state (Fig. 2e,f)32,33. Raman spectroscopy also provided evidence for this reconfiguration. The characteristic SOCl coordination peak showed a clear blue shift after adding LiAlCl and LiOTf, and both the antisymmetric and symmetric S-Cl bond stretching vibrations were split (Fig. 2g)20,32,34. These spectral features confirm that OTf⁻ interacts with both Al-Cl bridging bonds and S-Cl bonds. Such interactions support the reconfiguration driven by the TSSR strategy of the Li+ solvation structure, leading to faster Li+ desolvation and a changed Al-Cl anion coordination environment. Analysis of electrolyte solvation configurations from these studies also revealed that TSSR strategy reduces solvent-separated ion pairs (SSIPs) and contact ion pairs (CIPs), while increasing aggregated (AGGs) solvation structures (Fig. 2h and Supplementary Table 3). This TSSR-driven shift towards AGGs structures not only improves the envNironment for ion transport but also helps form a stable, anion-derived positive electrode-electrolyte int erphase. Theoretically, this shift toward AGG structures is beneficial for Li+ transport. In baseline electrolytes dominated by SSIP/CIP configurations, Li+ migration is often limited by the high energTy barrier required for desolvation from a rigid solvent cage. In contrast, the anion-rich AGG strucAtures provide a more dynamic coordination environment, offering low-energy pathways for Li+ to move between adjacent coordination sites without full desolvation. This mechanism enhances the intrinsic mobility of Li+, contributing to higher ionic conductivity and reduced polarization (Fig. 2i).

Mechanisms of TSSR-derived positive electrode-electrolyte interphase chemistry
Following our understanding of how the TSSR strategy impacts the Li+ coordination and bulk electrolyte properties (Fig. 2), we next investigated how this TSSR-modulated system guides the formation of a protective positive electrode-electrolyte interphase and influences its chemical makeup and operational mechanism. This understanding is key to addressing the persistent issue of electrolyte decomposition in Li||Cl batteries, a factor that significantly impacts their long-term sustainability. In Li||Cl battery systems, electrolyte decomposition during cycling is complex. The main reactions involving SOCl are generally described as equation (1) and (2)8,9,11:
4 Li + 2 SOCl → 4 LiCl + S + SO (1)
2 SOCl + 2 AlCl- → SO Cl + SCl + Cl + 2 AlCl + 2 𝒆− (2)

These reactions (1) and (2) produce various sulfur- and chlorine-bearing species. Ideally, these species would participate in subsequent reversible steps to reform SOCl , completing a closed-loop cycle that contributes to cell capacity as equations (3-6):
SO + Cl ↔ S O Cl (3)
S + Cl → SCl (4)
2 Li+ + SCl + 2 𝒆−→ 2 LiCl + S (5)
2 Li+ + SO Cl + 2 𝒆−→ 2 LiCl + SO (6)

While equations (3-6) are intended to contribute to cell capacity rather than represent parasitic pathways, baseline electrolyte formulations often exhibit formation of a patchy and unstable interphase and challenging operational environments. These factors promote excessive electrolyte decomposition, preventing complete reconversion and undermining reversibility, with the unrecovered fraction manifesting as parasitic losses. To counter these issues, our TSSR strategy is specifically designed to reconfigure the Li+ solvation environment. This approach aims to foster a more controlled interfacial chemistry and guide the formation of an effective interphase, thereby minimizing detrimental processes, improving the reversibility of key electrochemical reactions, and ultimately enhancing the overall sustainability of the battery system.

To further elucidate the chemical pathways underpinning these improvements, we used detailed time-of-flight secondary ion mass spectrometry (TOF-SIMS) to map the spatial distribution of key species within the interphase. Three-dimensional TOF-SIMS reconstructions (Fig. 3a) compare the distributions of CF ⁻, LiF⁻, and LiCl⁻—all critical for positive electrode-electrolyte interphase construction—in the baseline and TSSR electrolytes. After 100 cycles in the baseline electrolyte, the positive electrode surface showed sparse, isolated CF ⁻ clusters and a relatively shallow LiF⁻ distribution, while LiCl⁻ deposits were widespread and disorganized. This pattern suggests that in the baseline electrolyte, chloride deposition is uncontrolled, leaving large positive electrode arNeas unprotected and prone to excessive electrolyte decomposition and further side-product buildup (Supplementary Fig. 11), a conclusion supported by anion fragment depth profiling (Supplementary Fig. 12). In sharp contrast, the TSSR electrolyte (Fig. 3a) exhibited a much denser and mTore uniform distribution of CF ⁻, CF ⁻, CF⁻, and LiF⁻. These species together form a composite positive electrode-electrolyte interphase featuring an outer layer of C-F groups above an inner LiF-rich layer, indicating the formation of well-structured fluorinated positive electrode-electrolyte interphase components (Supplementary Fig. 13-15)35–37. Concurrently, LiCl distribution within this engineered positive electrode-electrolyte interphase was reduced and more uniform, suggesting better control over its deposition, which was further corroborated by post-cycling X-ray diffraction (XRD) analysis of the positive electrode (Supplementary Fig. 16 and 17). Two-dimensional TOF-SIMS images also clearly visualized the distributions and relative amounts of these anionic fragments (Supplementary Fig. 18 and 19). Collectively, these results confirm that the TSSR strategy promotes the formation of a cohesive, F-rich positive electrode-electrolyte interphase on the positive electrode surface. This well-defined interphase, with its outer C-F layer and inner LiF layer uniformly integrated with the positive electrode, not only minimizes electrolyte decomposition but also regulates lithium salt deposition, ensuring a more stable and sustainable interface under harsh cycling conditions (Fig. 3b).

To further validate the chemical nature of the TSSR-derived positive electrode-electrolyte interphase, X-ray photoelectron spectroscopy (XPS) was conducted on cycled positive electrodes. The S 2p spectra (Supplementary Fig. 20) revealed multiple sulfur species in both charged and discharged states. In the baseline electrolyte, sulfur tended to transition unevenly towards higher oxidation states, resulting in a broader distribution of partially oxidized byproducts and increased parasitic reactions. In contrast, in the TSSR electrolyte, peaks for higher-valence sulfur spNecies. were more uniformly distributed, and Cl-bound intermediates were reduced, suggesting a mor e controlled and reversible redox process. The observed shielding and deshielding effects during charge and discharge cycles highlight how the TSSR strategy, by creating a TSSR-induced recoTnfigured local environment, effectively stabilizes sulfur-containing intermediates. This stabiAlization reinforces the positive electrode-electrolyte interphase’s protective function and lessens unwanted side reactions, aligning with the protective positive electrode-electrolyte interphase model suggested by our earlier analyses35,37. Depth-profile XPS analyses of the cycled positive electrode surface offered further detailed insights into the positive electrode-electrolyte interphase’s chemical composition and uniformity. The F1s depth profiles (Fig. 3c, d) show that in cells with the TSSR electrolyte, the positive electrode surface has -CF groups, which can repel the electrolyte. OTf⁻ decomposition also generates -CF and -CF fragments that form an inner framework supporting the LiF-rich layer. Importantly, a clear LiF signal persists across multiple sputtering depths, confirming a continuous, inorganic-rich inner interphase. Additionally, depth profiles of Li 1s, C 1s, and Cl 2p (Supplementary Fig. 21 and 22) support the composite nature of this positive electrode-electrolyte interphase. The decreasing signal of side-products with more etching time shows that this interphase—resulting from the anion-directed decomposition pathway enabled by the initial solvation sheath reconfiguration—effectively suppresses electrolyte decomposition and protects the positive electrode.

Temperature-dependent electrochemical impedance spectroscopy (EIS) measurements (Supplementary Fig. 23) also support these XPS findings, highlighting this layered structure’s key role in reducing interfacial impedance and preventing further electrolyte degradation. Plotting the relative amounts of key anionic fragments versus sputtering time summarizes the interphase composition’s overall evolution (Fig. 3e). Consistent with linear sweep voltammetry (LSV) observations of electrolyte decomposition (Supplementary Fig. 24), the data indicate that in the baseline electrolyte, an effective positive electrode-electrolyte interphase barrier does not form. This allows more electrolyte or active chlorine species to undergo parasitic reactions at the electrode surface. This leads to increased buildup of sulfur-containing chloride byproducts and siAgnificant compositional variation through the interphase depth. In contrast, the TSSR electrolyte, with its TSSR-formed protective positive electrode-electrolyte interphase, maintains a high proportion of F-containing protective species (like LiF and C-F groups) throughout the interphase. This promotes uniform deposition, increases the exchange specific current (Supplementary Fig. 25), and leads to higher steady-state and initial currents (I ) (Supplementary Fig. 26). Consequently, a greater cumulative charge throughput is achieved (Supplementary Fig. 27). This translates to more efficient ion transport and interfacial charge transfer, enhancing interfacial stability and effectively suppressing further side reactions. These improvements ultimately lead to faster reaction kinetics, lower overpotentials, and potentially quicker reintegration of any benign electrolyte decomposition products during subsequent cycles35–37.

In summary, our comprehensive spectroscopic and electrochemical characterizations clearly show that the TSSR strategy yields a uniform, F-rich positive electrode-electrolyte interphase. This engineered interphase stabilizes the positive electrode interface by fundamentally changing Li+ coordination. This change directs the decomposition pathways of electrolyte components and suppresses parasitic reactions. Such an optimized interphase is crucial for improving ion transport and interfacial charge transfer. This enables the battery to cycle stably for over 600 cycles at 25 °C at a specific current of 2000 mA g⁻1 (Supplementary Fig. 28), substantially enhancing both reaction stability and cycling performance at ambient temperatures. These findings on the positive electrode-electrolyte interphase’s chemical composition and protective mechanisms lay a robust foundation for our subsequent examination of its specific microstructural and morphological characteristics.

Morphological characterization of the positive electrode and positive electrode-electrolyte interphase
Having established the chemical nature and TSSR-driven formation of the TSSR-derived positive electrode-electrolyte interphase (Fig. 3), we next used complementary surface characterization techniques to examine its physical structure and morphological changes during cycling (Fig. 4). Atomic force microscopy (AFM) first revealed nanoscale topographical details. In the baseline electrolyte, the positive electrode surface showed significant height variations and a highly uneven topography, indicating substantial parasitic deposits and increased polarization (Fig. 4a and Supplementary Fig. 29). In sharp contrast, in the TSSR electrolyte, the resulting positive electrode-electrolyte interphase dramatically smoothed the surface. This suggests the formation of a more uniform and protective positive electrode-electrolyte interphase that effectively limits uncontrolled electrolyte decomposition (Fig. 4b and Supplementary Fig. 30)38,39.

Transmission electron microscopy (TEM) provided further support for these AFM findings, offering higher-resolution microstructural details. In the baseline electrolyte, the interphase on the positive electrode was visibly thick, porous, and loosely bound, making it prone to cracking and delamination during electrochemical cycling (Fig. 4c). This unfavorable morphology remained even after 500 cycles under the same conditions, with the positive electrode exhibited a clearly heterogeneous interface (Supplementary Fig. 31). In contrast, cells with TSSNR electrolyte consistently showed a notably compact and thin interphase, whether cycled for 100 or 5 00 times. Such a stable and well-defined interphase is key to reducing parasitic reactions and interfacial impedance (Fig. 4d and Supplementary Fig. 31). Importantly, even after 100 cycles at a demaTnding –40°C, cells with TSSR electrolyte kept this thin and compact positive electrode-electrolyte interphase. This highlights the robust and consistent formation of the TSSR-derived interphase over a wide temperature range (Supplementary Fig. 32), a feature important for sustainable operation in varied climates. Scanning electron microscopy (SEM) images complemented the AFM and TEM findings, clearly showing the macroscopic differences in surface morphology. Positive electrodes cycled in the baseline electrolyte were covered with non-uniform, bulk-like deposits, typical of uncontrolled interfacial reactions and significant byproduct buildup (Fig. 4e and Supplementary Fig. 33). Even at –40°C, where LiCl nucleation rates might change, substantial particulate side products still formed and gathered at the interface, adding to cell polarization (Supplementary Fig. 34 and 35). In stark contrast, the TSSR strategy ensured the positive electrode surface remained notably uniform and largely free of significant side-product deposits at both 25°C and –40°C. This confirmed the formation of a stable and protective positive electrode-electrolyte interphase (Fig. 4f and Supplementary Fig. 33 and 35), which is essential for reliable and sustainable battery function.

Collectively, these multi-scale morphological analyses clearly show that the TSSR strategy not only reconfigures the ternary solvation sheath but, critically, also directs the formation of a durable, uniform, and F-rich interphase (Supplementary Fig. 36). This engineered positive electrode-electrolyte interphase, stemming directly from the initial solvation sheath reconfiguration, plays a key role in reducing the Li+ desolvation barrier and improving ion transport. This is further substantiated by EIS results (Supplementary Fig. 37), which reveal a significanNt increase in interfacial resistance for the baseline cell after extended cycling, while the cells with TSS R electrolyte maintains a more stable and lower-resistance interface. These improvements contribute significantly to the enhanced cycling stability and reduced polarization seen in Li||Cl batteries, particularly under low temperature, paving the way for more sustainable and resilient energy storage38,40.

Electrochemical performance at low temperatures
The practical operation of Li||Cl batteries is often limited under low temperature, such as rapid cycling and very low temperatures. At these temperatures, slow interfacial charge-transfer and increased electrolyte decomposition severely hinder battery performance. Key kinetic bottlenecks include limited Li+ transport and desolvation at the electrode-electrolyte interface. Our investigations into the electrolyte’s solvation chemistry (Fig. 2) have shown that the TSSR strategy (via LiOTf) promotes an effective TSSR, leading to improved Li+ desolvation. This enhanced desolvation is anticipated to facilitate faster interfacial kinetics. The benefits of this reconfigured solvation environment are evident from the initial discharge cycle, where the nucleation overpotential is eliminated, thereby establishing a stable foundation for cryogenic cycling (Supplementary Fig. 38). Based on these findings, we then evaluated how this TSSR approach could support long-life, high-current cycling at low temperatures, a critical aspect for developing batteries with greater operational sustainability across diverse environmental conditions. Consistently, the TSSR electrolyte enabled significant improvements in both high-rate capability and cycle life at low temperatures (Fig. 5a). Specifically, when cycled at –40°C under a demanding specific current of 1000 mA g⁻1, the TSSR electrolyte maintaining capacity retention of 99.2% and Coulombic efficiency of 99.2% for over 1100 cycles. The initial capacity variation oNbserved within the first ≈50 cycles is attributed to the electrochemical formation and stabilization of the positive electrode-electrolyte interphase. During this period, the OTf⁻ anion gradually decomposes to form the protective, fluorine-rich interphase. Once this positive electrode-electrolyte inTterphase is fully established, a stable interface is provided for all subsequent reactions, leadAing to the stable capacity plateau. In sharp contrast, the baseline electrolyte cell began to show significant capacity decay and fluctuating Coulombic efficiency after approximately 300 cycles under the same conditions (Fig. 5a and Supplementary Fig. 39, 40). To further validate the robustness of the TSSR strategy, cycling tests were performed at a high reversible capacity of 1500 mAh g⁻1. The TSSR electrolyte demonstrated stable operation for over 200 cycles at –40°C, a significant improvement over the baseline electrolyte cell which failed within 100 cycles (Supplementary Fig. 41). The stable cycling stability at low temperatures represents a notable step forward for Li||Cl / Na||Cl battery technology operating in such environments, enabling extended operation with high Coulombic efficiency even at high specific currents (Fig. 5b and Supplementary Table 4)11,14,21,22. Furthermore, the stability of the TSSR electrolyte was confirmed at a higher positive electrode loading of 4 mg cm⁻2, where it maintained stable cycling for 200 cycles at –40°C, in contrast to the rapid failure of the baseline cell (Supplementary Fig. 42).

Crucially, during extended cycling, TSSR electrolyte showed substantially lower charge/discharge polarization (0.61 V at 100 cycles and 0.93 V at 900 cycles) than those with the baseline electrolyte (0.92 V and 1.86 V, respectively) (Supplementary Fig. 43 and 44). Additionally, the charging plateau voltage lag, which often indicates increased polarization after low-temperature cycling, was significantly reduced from 0.29 V in the original system to just 0.08 V in the TSSR electrolyte (Fig. 5c). These improvements are due to the effective positive electrode-electrolyte interphase formed through TSSR and subsequent anion-directed decomposition. This robust interphase prevents continuous excessive electrolyte decomposition, thus maintaining a uniform interface free of excessive irreversible byproducts. Such an interface promotes better kinetics and a quicker start to the LiCl → Cl conversion, supporting our earlier mechanistic understanding.

The robustness of the TSSR electrolyte was further underscored by its performance at a low temperature of –80°C. Even under these conditions, TSSR electrolyte delivered reliable cycling stability, maintaining consistent performance for over 100 cycles at a current of 200 mA g⁻1 with a specific capacity of approximately 400 mAh g⁻1 (Fig. 5d). This clearly demonstrates the potential of the engineered electrolyte for applications in severe cryogenic environments, enhancing the sustainability of energy solutions in such demanding settings.

Further insights into the internal reaction dynamics and the regulatory effect of the modified electrolyte on polarization and interfacial side reactions were gleaned from differential capacity (dQ/dV) analysis (Fig. 5e). In the TSSR electrolyte, the dQ/dV profiles revealed that the reversible electrolyte redox peak around 3.7 V remained stable over 500 cycles, exhibiting minimal polarization shift (Fig. 5e and Supplementary Fig. 45 and 46). In contrast, baseline electrolyte cells showed substantial polarization, with this reversible peak vanishing after only 200 cycles, indicative of inhibited SOCl reformation due to excessive electrolyte decomposition (Fig. 5e and Supplementary Fig. 43, 47, and 48). Moreover, at the high-voltage charging plateau, baseline electrolyte cells displayed prominent side-reaction peaks, confirming persistent electrolyte over-decomposition at high potentials. Conversely, the TSSR electrolyte maintained stable reaction peaks, providing clear evidence that the robust positive electrode-electrolyte interphase effectively suppresses excessive SOCl 2 decomposition (Fig. 5e and Supplementary Fig. 45-48). Such stabilization supports the smooth and reversible conversion of active species during long-term cycling, thereby preserving capacity and reducing interfacial polarization, which are vital for achieving sustainable battery operation 12,23,41. This stabilization is also reflected in the galvanostatic discharge profiles, stemming from Aa TSSR-driven capacity redistribution between the two competing redox pathways (Supplementary Fig. 49). The CV analysis confirms the TSSR strategy not only sustains the high-voltage S-Cl species pathway but also significantly reduces the polarization of the main Cl →LiCl 2 reaction. This redistribution to the higher-potential S-Cl pathway enhances the overall energy efficiency.

Collectively, these analyses culminate in the interfacial mechanism summarized in Fig. 5f, rooted in the TSSR. The TSSR strategy initiates this reconfiguration by displacing SOCl from the primary Li+ solvation sheath and, through its interactions with Li+ and AlCl ⁻, establishing an anion-bridged, anion-rich solvation structure. This reconfigured environment markedly enhances Li+ desolvation and overall ion transport. Critically, following this TSSR, the high-HOMO OTf⁻ undergoes preferential decomposition at the positive electrode, yielding a stable, bilayer composite positive electrode-electrolyte interphase. This positive electrode-electrolyte interphase effectively suppresses excessive electrolyte decomposition, thereby reducing interfacial polarization and significantly boosting long-term cycling performance. The TSSR-enabled Li||Cl system thus benefits from a synergistically reconfigured ternary solvation sheath where LiOTf, LiAlCl , and SOCl interact dynamically. This TSSR-driven synergy not only reshapes solvation chemistry and lowers the Li+ desolvation energy barrier but also critically regulates the SOCl decomposition pathway (Fig. 5f). As a result, Li||Cl batteries employing this TSSR strategy show better cycling performance and much lower interfacial polarization under low-temperature conditions. This clearly validates our approach to additive selection and interfacial engineering, paving the way for more sustainable and reliable battery operation in harsh environments.

Methods
Materials availability
Thionyl chloride (SOCl , 99 %, Aladdin), lithium tetrachloroaluminate (LiAlCl , 98.0 %, Macklin), lithium trifluoromethanesulfonate (LiOTf, 99.0 %, Aladdin) and lithium bis(fluorosulfonyl)imide (LiFSI, DoDoChem) were used to prepare the electrolytes. All reagents were transported in argon-filled sealed packages, dried, and subsequently stored in an argon-filled glovebox where the H O/O content was maintained below 0.01 ppm. Before use, LiFSI was further dried overnight in a vacuum oven at 100°C. Ordered mesoporous carbon (CMK-3) was purchased from XFNANO. Commercial activated carbon (AC) was purchased from DoDoChem. Commercial lithium metal disks (diameter: 15.6 mm, thickness: 0.45 mm, purity: 99.9%) were purchased from Canrd. These pre-cut electrodes were stored in an argon-filled glovebox (H O < 0.1 ppm, O < 0.1 ppm) and used directly without further surface treatment or rolling processes to minimize handling artifacts.

Preparation of electrolyte
Two types of electrolytes were prepared and used in this study. The baseline electrolyte (baseline) was prepared by dissolving 1.5M LiTAlCl and 0.1M LiFSI in 1 mL of SOCl . The TSSR electrolyte was prepared by adding 0.3M ALiOTf to this baseline electrolyte formulation. All mixtures were stirred for 20 min, and the resulting colorless supernatants were taken as the working electrolytes.

Preparation of positive electrode host
The positive electrode was prepared by mixing CMK-3 (XFNANO, 99.9%), Super P (Canrd, 99.9%), and polyvinylidene fluoride (PVDF, PVDF-900) at a weight ratio of 8:1:1. The powders were dispersed in N-methyl-2-pyrrolidone (NMP, electronic grade, 99.9%, Aladdin) using a planetary mixer for 30 min to form a homogeneous slurry. The slurry was manually coated onto pre-cut 304 stainless-steel disks (diameter: 15.5 mm, thickness: 0.5 mm), which had been previously cleaned via ultrasonication in ethanol. Finally, the electrodes were dried in a vacuum oven at 80 °C for 16 h without further cutting. The CMK-3 loading was 2.0 ± 0.2 mg cm⁻2 for standard tests and 4.0 ± 0.2 mg cm⁻2 for the high-loading experiments.

The baseline positive electrode was prepared by mixing AC (DoDoChem, 99%), Super P (Canrd, 99.9%), and polyvinylidene fluoride (PVDF, PVDF-900) at a weight ratio of 8:1:1. The powders were dispersed in N-methyl-2-pyrrolidone (NMP, electronic grade, 99.9%, Aladdin) using a planetary mixer for 30 min to form a homogeneous slurry. The slurry was manually coated onto pre-cut 304 stainless-steel disks (diameter: 15.5 mm, thickness: 0.5 mm), which had been previously cleaned via ultrasonication in ethanol. Finally, the electrodes were dried in a vacuum oven at 80 °C for 16 h without further cutting. The AC loading was 2.0 ± 0.2 mg cm⁻2 (Supplementary Fig. 50).

Battery assembly
All cells were assembled inside aTn argon-filled glovebox with H O/O levels maintained below 0.01 ppm. Coin cells (CR2032, 316A stainless-steel casing) were fabricated by stacking the pre-prepared CMK-3 positive electrode, one layer of commercial glass fiber separator (GF/D, Whatman; diameter: 19 mm, thickness: 675 μm, average pore size: 2.7 μm, porosity: ~90%), and a lithium-metal foil negative electrode. The potential for corrosion of the stainless-steel casing was evaluated via post-cycling analysis, which indicated that it was not a significant factor under the tested conditions (Supplementary Fig. 51, 52). A total of 100 μL of electrolyte was added in two aliquots to thoroughly wet the positive electrode and separators.

Characterizations
X-ray diffraction (XRD) patterns were characterized by a Bruker-AXS D8 Advance. Morphology of the cycled positive electrode were investigated by using scanning electron microscope (SEM, Hitachi Regulus 8230), transmission electron microscope (TEM, Thermo Scientific Talos F200X). Raman spectral was obtained by Raman (HORIBA HR Evolution) of 532 nm wavelength. Surface chemical bonding states of the cycled positive electrodes were analyzed by X-ray photoelectron spectroscopy (XPS, escalab 250Xi). Depth profiling was conducted with a primary Bi3+ beam of 30 keV and a scanning area of 100×100 µm2. Energy-dispersive X-ray (EDX) spectroscopy was tested by scanning electron microscope (SEM, Hitachi Regulus 8230). Time of flight secondary ion mass spectrometry (TOF-SIMS) data were acquired from PHI nanoTOF II Time-of-Flight SIMS. The nuclear magnetic resonance (NMR) data were obtained from a Bruker 600M NEO liquid NMR spectrometer equNipped with an iProbe BBFO 5mm BBF/1H probe with a frequency range of 19F/31P-109Ag. The ato mic force microscope (AFM) data were obtained from a Bruker Dimension ICON with an image resolution of 256×256. Pore Structure Characterization Nitrogen adsorption-desorption isothermTs were measured at 77 K using a BELSORP-mini II analyzer (MicrotracBEL, Japan) aftAer degassing the samples at 200 °C for 12 h under vacuum. The specific surface area and pore size distribution were calculated using the Brunauer–Emmett–Teller (BET) method and the Barrett-Joyner-Halenda (BJH) model, respectively. Electrochemical measurements were conducted at a strictly controlled temperature of 25 ± 1 °C inside an environmental chamber (MIHW-200-160CH-B, Neware), with the cells connected to a Land CT3002A battery testing system. For low-temperature testing, the cells were placed in an ultra-low-temperature freezer (MELNG DW-HW50, −40°C ~ −86 ± 1 °C) while their leads remained connected to Land CT3002A test channels outside the freezer. Cyclic voltammetry (CV), linear sweep voltammetry (LSV), Tafel analysis, and polarization I–t overpotential-deposition tests were performed on a Gamry Reference 5000 workstation. Electrochemical impedance spectroscopy (EIS) measurements were performed in potentiostatic mode at the open-circuit voltage (OCV) with an AC perturbation amplitude of 10 mV r.m.s over a frequency range from 100 kHz to 0.1 Hz. A data density of 10 points per decade was used. Prior to each EIS measurement, the cells were rested at OCV for 30 min to strictly ensure a quasi-stationary state. For post-cycling characterizations (XPS, TOF-SIMS, SEM, TEM), positive electrodes were harvested from cells after a specified number of cycles and consistently disassembled in a fully discharged state. The harvesting and sampling processes were strictly performed in an argon-filled glovebox (H O < 0.1 ppm, O < 0.1 ppm) maintained at 25 ± 1 °C. Prior to analysis, the retrieved positive electrodes were gently rinsed with high-purity dimethyl carbonate (DMC) to remove residual electrolyte sNalts and subsequently dried under vacuum overnight inside the glovebox. To prevent atmospheric contamination, the samples were sealed in a specialized vacuum transfer holder (for XPS/TOF-SIMS) or argon-filled airtight containers (for SEM/TEM) during transport from the glovebox to the analysis instruments. Similarly, for electrolyte characterizations, Raman spectroscopy measAurements were conducted using samples sealed in airtight glass cuvettes inside the glovebox, and NMR samples were prepared in sealed NMR tubes to strictly exclude moisture and oxygen during testing.

Theoretical calculations
Density Functional Theory (DFT) calculations were performed using the Gaussian 16 software package to obtain the Highest Occupied Molecular Orbital (HOMO) and Lowest Unoccupied Molecular Orbital (LUMO) energies, as well as the Electrostatic Potential (ESP). All structures were fully optimized at the B3LYP hybrid functional level using the 6-31++G(d,p) basis set for carbon (C), hydrogen (H), oxygen (O), sulfur (S), and fluorine (F) atoms. MD simulations were performed in GROMACS using the General Amber Force Field (GAFF). Topology files and bonded and Lennard-Jones parameters were generated by using the Autoff while the ADCH atomic charges from Multiwfn3.8 program were used. The cutoff for the Lennard-Jones potential was set to 12 Å. The long-range Coulombic interactions were counted by a particle-particle particle-mesh. The initial periodic systems were set up using PACKMOL. All ions and molecules were inserted in an initial cube box with 10-nm sides. For the TSSR electrolyte, the simulation box was constructed using 2754 SOCl molecules, 380 Li+ ions, 360 AlCl ⁻ ions, 100 OTf⁻ ions, and 20 FSI⁻ ions. The simulation box for the baseline electrolyte contained 2754 SOCl molecules, 380 Li+ ions, 360 AlCl 4⁻ ions, and 20 FSI⁻ ions. In the equilibriNum stage of the system, the energy of the simulated system was minimized by the conjugate gradien t method first, then the equilibrium simulation was carried out under NPT ensemble for 10 ns. Finally, the simulation was continued for 20 ns with NVT ensemble and data were collected. Only the final 10-ns trajectory was sampled for the analysis of radial distribution function and solvent-soluAte interaction environments. The optimized atomic coordinates and MD simulation structures are provided as Supplementary Data 1.

Peer review rounds
[{"round": 1, "reviewer_comments": {"reviewer_1": "This manuscript reports an electrolyte additive for lithium-chlorine (Li-Cl₂) batteries and investigates its mechanism through studies on the CEI (Cathode Electrolyte Interphase) and charge-transfer kinetics. The fabricated batteries demonstrate stable cycling performance at low temperatures. The article presents rich data analysis. It can be considered for acceptance after addressing the following issues and providing more critical supporting data:\n1.Comparison of the first discharge curves of batteries (with/without LiOTf) is needed.\n2.Cycling performance data at higher reversible capacity (e.g., 1200 mAh/g) is needed. Low capacity is known to enable long cycle life. I would like to know if the additive's effect remains significant under high-capacity cycling.\n3.The cathode loading might need to be further increased. Why did authors choose the ordered mesoporous carbon (CMK-3)as cathode material?\n4.The three discharge plateaus in Fig. S38 (>3.5 V, ~3.0 V, and one < 3.0 V at the end of discharge) require analysis. According to reported studies, the highest plateau corresponds to the reduction of SCl₂/S₂Cl₂. Why is this plateau longer with the additive? And why is the main Cl₂ reduction plateau (~3.0 V) shorter? Analysis combining with CV is needed, but the current CV analysis is unclear.\n5. Please provide comparative charging/discharging curves of the batteries at different temperatures. Also, provide comparative cycling and charging/discharging curve data for batteries with and without the additive at room temperature.\n6.Fig. S13 (with additive? But the caption says \"without LiOTf\" – is this a labeling error?) shows almost no S. However, the first discharge should generate a large amount of S in cathode due to the reduction of SOCl2. How to explain the disappearance of S? Although S is slightly soluble in SOCl₂, the control group (Fig. S11) shows significant sulfur. How to explain this?\n7.The scale bars in Fig. S34 are not clear, and the magnifications are inconsistent. This is very confusing.\n8.The SEM morphology of the cathode at -40°C: Fig. S34 (second row) and Fig. S35b show excessive differences. Is it because they are not at similar cycle numbers? Fig. S36 (SEM morphology of cathode with additive) shows excessive differences compared to Fig. S34 and Fig. 4f (which also show morphology with additive). The authors frequently mention \"after cycling\", please specify the exact cycle number.", "reviewer_2": "In the manuscript entitled \"Ternary Solvation Sheath Reconfiguration Drives Sustainable Cryogenic Li-Cl2 Batteries\", the authors presented an advancement in Li-Cl2 batteries by addressing interfacial instability at cryogenic temperatures through a Ternary Solvation Sheath Reconfiguration strategy. Using LiOTf as an additive, the authors reconfigure the Li+ solvation environment to form a stable fluorine-rich cathode-electrolyte interphase, enabling improved cycling stability. However, the novelty and breakthrough are insufficient, and the manuscript can’t meet the high standard of Nature Communications. Some suggestions are listed here for authors to address tricky issues.\n1. Near line 167 of page 9, the authors state that rapid electrolyte decomposition leads to severe performance degradation, including a sharp increase in interfacial resistance. However, the evidence provided in Supplementary Figures 2 and 3 does not adequately support this claim. It is recommended that the authors supplement or clarify this data with additional experiments, such as impedance spectroscopy results directly linking electrolyte decomposition to resistance rise, or revise the claim to align with the presented evidence.\n2. A comparison of polarization at −40°C after 900 cycles is presented in Fig. 5c. However, this analysis is flawed because, as indicated in Fig. 5a, the battery without LiOTf (\"w/o LiOTf\") is severely degraded and no longer functional after 900 cycles. Consequently, the comparison lacks validity and distorts the conclusions.\n3. The manuscript describes Supplementary Figure 28 as depicting a capacity of approximately 1500 mAh g-1 and a coulombic efficiency exceeding 99%. However, the actual data appears inconsistent with these values. I strongly advise the authors to re-examine the raw data, correct any errors, and ensure that the figure labels, captions, and textual descriptions align precisely.\n4. Supplementary Table 4 lists comparative examples but fails to match the cited references accurately. Upon review, the descriptions or values in the table do not correspond to the references provided.\n5. The \"Battery Assembly\" section indicates the use of coin cells (CR 2032) with a 316 stainless-steel casing. Given the well-documented high reactivity of Cl2 species toward stainless steel, which can accelerate corrosion and compromise cell safety.\n6. It is recommended that the authors conduct rigorous checks across the manuscript, ensuring formatting compliance, optimizing figure resolutions, and standardizing abbreviations, especially in the \"Characterization\" section.", "reviewer_3": "This manuscript presents an interesting “Ternary Solvation Sheath Reconfiguration (TSSR)” strategy to address the critical challenge of interfacial instability in rechargeable Li-Cl2 batteries. By introducing LiOTf as a functional additive, the authors demonstrate the rational design of a stable, fluorine-rich cathode-electrolyte interphase (CEI) through engineering of the Li+ solvation environment. The claims are well-supported by a combination of spectroscopic, electrochemical, and computational analyses. The proposed design on CEI achieved impressive stability of 1100 cycles at -40 °C, providing potential applications for energy storage in extreme environments. Overall, the work is innovative with high quality. Therefore, I would like to recommend its publication in Nat. Commun. after the following comments and suggestions are addressed.\n1. The result in Fig. 2h regarding the shift towards AGG structures is noted. The manuscript would benefit from a brief comment in the main text on the theoretical implications of this structural shift for Li+ transport dynamics, which can enhance the understandings on solvation chemistry.\n2. The cycling stability in Fig. 5a is a key electrochemical parameter. For improved clarity, the authors should explain the phenomenon of the initial capacity variation within the first ≈50 cycles.\n3. The authors have summarized the work’s significance. It is suggested that they slightly expand the discussion on the potential generality of the TSSR strategy for other high-voltage battery systems that face similar challenges in electrolyte electrochemical stability.\n4. Regarding the post-cycling characterizations such as XPS and TOF-SIMS, the authors should specify the state of the cathode and any pre-treatment steps in the Methods section to enhance the reproducibility.\n5. In Methods section, the cathode mass loading is described as ≈2.0 mg cm-2. To enhance the reproducibility, the authors should provide a more precise range or an average value with standard deviation for the CMK-3 loading across the tested cells.\n6. For better reproducibility of MD simulations, it is highly recommended to provide the exact number of each type of molecule and ion (SOCl2, Li+, AlCl4-, OTf-, etc.) used to construct the simulation box in the Methods section."}, "author_response": "Response to Reviewers’ Comments\nDear Editors and Reviewers:\nWe would like to greatly appreciate you giving us the opportunity to revise our manuscript.\nWe carefully studied the reviewer’s comments and tried our best to revise the manuscript according\nto the comments. The manuscript has been revised following the comments and suggestions of the\nreviewers, and point by point replies are given below. Thanks again to the editors and reviewers for\ntheir hard work.\nReviewers’ comments:\nReviewer #1 (Remarks to the Author):\nThis manuscript reports an electrolyte additive for lithium-chlorine (Li-Cl ) batteries and investigates\n2\nits mechanism through studies on the CEI (Cathode Electrolyte Interphase) and charge-transfer kinetics.\nThe fabricated batteries demonstrate stable cycling performance at low temperatures. The article\npresents rich data analysis. It can be considered for acceptance after addressing the following issues\nand providing more critical supporting data.\nResponse: We sincerely thank the reviewer for the thorough evaluation and positive assessment of this\nwork. These critical suggestions have been invaluable in improving our manuscript. We have addressed\nevery point in detail, incorporating new supporting data and expanded analysis. Our responses are\noutlined below, and we hope the revised manuscript is now suitable for publication.\n1. Comparison of the first discharge curves of batteries (with/without LiOTf) is needed.\nFig. R1|Initial galvanostatic discharge profiles. Comparison of the first cycle galvanostatic\ndischarge profiles for Li-Cl cells with baseline electrolyte and TSSR electrolyte at a, 25°C and b, –\n2\n40°C.\nResponse: We thank the reviewer for this helpful suggestion. As requested, a comparison of the initial\ndischarge profiles has been added to the revised manuscript (Fig. R1).\nThe data reveals a distinct voltage dip at the start of discharge for baseline electrolyte and TSSR\nelectrolyte at both 25 °C and –40 °C (Fig. R1a, b). This feature is characteristic of the nucleation\noverpotential required for LiCl formation. In the TSSR electrolyte, this nucleation overpotential is\nabsent, resulting in a smooth discharge profile. This result suggests that the reconfigured Li+ solvation\nsheath facilitates a more uniform and energetically favorable nucleation of LiCl. This facilitation\noccurs via two main effects. Firstly, the reconfigured, anion-rich solvation sheath lowers the Li+\ndesolvation energy barrier, which is the primary kinetic bottleneck for nucleation in the baseline\nelectrolyte. This allows the reaction to proceed smoothly without a large initial overpotential. Secondly,\nthese anion-rich aggregates may act as pre-formed nucleation sites where Li+ and Cl⁻ sources are\nalready in close proximity, reducing the thermodynamic barrier for LiCl formation and promoting\nuniform deposition across the cathode. This optimized initial deposition provides a stable foundation\nfor the subsequent formation of the protective CEI during the first charge.\nThis new figure and the corresponding discussion have been incorporated into the revised\nmanuscript Page 23, Line 442, Supplementary Fig. 38.\n2. Cycling performance data at higher reversible capacity (e.g., 1200 mAh/g) is needed. Low\ncapacity is known to enable long cycle life. I would like to know if the additive’s effect remains\nsignificant under high-capacity cycling.\nResponse: Thank you very much for this critical and important point. To address the reviewer’s\ncomment, new cycling experiments were carried out at an increased reversible capacity of 1500 mAh\ng⁻1. The results are presented in the Fig. R2.\nAs shown in Fig. R2f, the TSSR electrolyte maintained stable operation for 200 cycles at –40°C. In\ncontrast, the baseline electrolyte cell failed in fewer than 100 cycles under the same conditions. A\nsimilar stability enhancement was also observed at 25 °C (Fig. R2c).\nSustaining high-capacity cycling at cryogenic temperatures is challenging due to slower Li+\ndesolvation kinetics. The improved performance is attributed to the TSSR-induced reconfiguration of\nthe Li+ solvation shell, which enhances desolvation capability and mitigates this kinetic bottleneck.\nThese results demonstrate that the TSSR strategy is effective for achieving stable, high-capacity\ncycling under demanding conditions.\nWe have added this new data and corresponding discussion to the revised manuscript, Page 24, Line\n468, Supplementary Fig. 41.\nFig. R2|Cycling stability at a high specific capacity, comparing the baseline electrolyte and the\nTSSR electrolyte. a,b, Charge-discharge profiles for the 1st and 100th cycle at 25°C and a current\ndensity of 2000 mA g⁻1. c, Corresponding cycling performance at 25°C. d,e, Charge-discharge profiles\nfor the 1st and 100th cycle at –40°C and a current density of 1000 mA g⁻1. f, Corresponding cycling\nperformance at –40°C. These cells cycling was conducted at a reversible capacity of 1500 mAh g⁻1.\n3. The cathode loading might need to be further increased. Why did authors choose the ordered\nmesoporous carbon (CMK-3) as cathode material?\nResponse: Thank you very much for these critical questions regarding our cathode design and\nvalidation.\nFollowing the reviewer’s suggestion, we have performed experiments with an increased cathode\nloading of 4 mg cm⁻2. As presented in the Figure R3, the superiority of the TSSR strategy is clearly\nvalidated even at this more practical, high loading. At 25°C (Fig. R3a-c), the TSSR electrolyte delivers\nhighly stable cycling for 200 cycles, whereas the baseline electrolyte cell fails rapidly after only ~75\ncycles with severe capacity fade. This performance gap is even more pronounced at –40°C (Fig. R3d-\nf). The TSSR electrolyte not only exhibits excellent cycling stability but also maintains a low\npolarization; in contrast, the baseline electrolyte cell suffers from significant capacity degradation and\na large, continuously growing polarization. This demonstrates the robustness of our TSSR strategy\nunder more practical conditions.\nFig. R3|Electrochemical performance at a high cathode loading of 4 mg cm⁻2. Comparison of Li-\nCl baseline electrolyte and TSSR electrolyte. a, Cycling performance at 25°C and 1000 mA g⁻1. b, c,\nat –40°C and 1000 mA g⁻1. e, f, Corresponding charge-discharge profiles at the 50th and 150th cycle\nat –40°C.\nRegarding the selection of the cathode host, CMK-3 was specifically chosen over conventional high-\nsurface-area carbons (e.g., activated carbon, AC) due to its optimized pore structure for the Cl /LiCl\n2\nconversion. While conventional microporous carbons often possess a non-uniform pore distribution\nwith a high fraction of ultra-micropores (< 0.7 nm), these small pores can be detrimental. They provide\ninsufficient space for the solid LiCl product, leading to pore blockage and limiting the reaction kinetics,\nparticularly at high rates (Angew. Chem. Int. Ed. 2023, 62, e202215342). In contrast, CMK-3 offers a\ngood balance of high surface area and well-ordered mesopores (average pore size ~4 nm). This\nstructure provides sufficient volume to accommodate the LiCl product and continuous channels for\nion transport, which is critical for efficient Cl conversion.\nwith a conventional (AC) host under identical conditions. The charge-discharge profiles at the 100th\ncycle are shown in Fig. R4. The cell with the CMK-3 cathode exhibits significantly lower overall\npolarization than the cell with the AC cathode. Notably, the AC cathode displays a continuously\nrising charging profile without a clear plateau, indicative of severe kinetic limitations. This\nsuggests that the solid LiCl product becomes trapped within the microporous structure of AC, making\nits electrochemical oxidation difficult and leading to massive polarization. In contrast, the CMK-3\ncathode maintains a much flatter and lower charging plateau, demonstrating that its ordered\nmesoporous structure facilitates a more reversible Cl /LiCl conversion. Therefore, CMK-3 was\n2\nselected as the model host to reliably evaluate the electrolyte-focused TSSR strategy.\nFig. R4|Electrochemical comparison of cathode hosts. Charge-discharge profiles for Li-Cl cells\n2\nusing CMK-3 and activated carbon (AC) cathodes with TSSR electrolyte at the 100th cycle, measured\nat –40°C and 1000 mA g⁻1. The lower overall polarization and flatter charging plateau of the CMK-3\ncathode, in contrast to the high and rising charging voltage of the AC cathode, highlight the kinetic\nadvantages of the ordered mesoporous structure.\nWe have added the new high-loading data and a brief discussion on the cathode selection to the\nrevised manuscript, Page 25, Line 476, Supplementary Fig. 42, 50.\n4. The three discharge plateaus in Fig. S38 (>3.5 V, ~3.0 V, and one < 3.0 V at the end of discharge)\nrequire analysis. According to reported studies, the highest plateau corresponds to the reduction of\nSCl /S Cl . Why is this plateau longer with the additive? And why is the main Cl reduction plateau\n2 2 2 2\n(~3.0 V) shorter? Analysis combining with CV is needed, but the current CV analysis is unclear.\nFig. R5|Electrochemical evidence for the TSSR-modulated synergistic redox mechanism. a,\nCyclic voltammograms (CVs) of the TSSR electrolyte at 25°C and –40°C, illustrating the transition\nfrom a single dominant reduction peak (~3.09 V) at room temperature to a two-step redox pathway\n(peaks at ~2.85 V and ~3.62 V) at cryogenic temperature. b, Corresponding CVs at –40°C comparing\nthe baseline electrolyte with the TSSR electrolyte, revealing a significant positive shift in the main\nreduction potential (Cl →LiCl) and a contribution from the high-voltage S-Cl species pathway. c, d,\nResponse: We thank the reviewer for this insightful question. Indeed, at the room temperature, only\none dominant electrochemical reaction platform corresponding to the Cl →LiCl conversion is around\n2\n~3.4 V in Li-Cl batteries. However, when it comes to –40°C as shown in Fig. R5, which is already\n2\nbelow the boiling point of Cl , it occurs two main reversible electrochemical reaction platform, one\n2\nat >3.5 V corresponding to the redox of S-Cl species, and another at ~3.0 V for the Cl →LiCl\n2\nconversion. This could be probably attributed to the sluggish kinetics of liquid Cl , which allows the\n2\nredox reactions of S-Cl species (at >3.5 V) to emerge as a competing pathway in low temperature.\nThis phenomenon was also reported in a few previous literatures (Adv. Mater. 2024, 36, 202307192).\nTo further illustrate the temperature-dependent reaction pathways, a cyclic voltammogram (CV)\ncomparison of the TSSR electrolyte at 25°C and –40°C is provided in Fig. R5a. At 25°C, one dominant\nreduction peak (~3.09 V) is observed while at –40°C, two distinct reduction peaks (~2.85 V and ~3.62\nV) are evident.\nIt is also worthy of noted that the S-Cl species plateau (>3.5 Vcould be reversible and contributes\nto the total capacity under the extreme low temperature (Adv. Mater. 2024, 36, 202307192; J. Am.\nChem. Soc. 2025, 147, 18541–18549). Thus, in the baseline electrolyte, the unstable interface leads to\npassivation, causing this high-voltage pathway to progressively fade, as clearly seen in the 900th cycle\n(Fig. R5d). The TSSR strategy prevents this passivation and enhances its reversibility, thus sustaining\nthis capacity contribution. This also clarifies the behavior of the Cl\n2\n→LiCl plateau (~3.0 V), which\nis a direct result of capacity redistribution. The CV analysis in Fig. R5b provides the quantitative\nevidence for this hypothesis. Compared to the baseline electrolyte, the TSSR strategy not only shifts\nthe Cl reduction peak positively from 2.86 V to 2.94 V, indicating significantly reduced polarization,\n2\nbut also results in a more prominent reduction peak for S-Cl species (~3.66 V).\nThis observed change in relative CV peak intensities (Fig. R5b) directly corresponds to the\ngalvanostatic profiles at the 50th cycle (Fig. R5c), where the TSSR electrolyte exhibits a longer high-\nvoltage S-Cl plateau and a correspondingly shorter main Cl plateau. This confirms that the TSSR\n2\nstrategy redistributes a portion of the total capacity to the higher-potential S-Cl pathway, enhancing\noverall energy efficiency.\nWe have added this new data and corresponding discussion to the revised manuscript, Page 26, Line\n512, Supplementary Fig. 49.\n5. Please provide comparative charging/discharging curves of the batteries at different temperatures.\nAlso, provide comparative cycling and charging/discharging curve data for batteries with and without\nthe additive at room temperature.\nResponse: Thank you very much for this valuable suggestion to include a more comprehensive dataset.\nAs requested, we have provided all the relevant data in a composite figure in the revised Supporting\nInformation (Fig. R6).\nFirstly, the TSSR electrolyte demonstrates excellent adaptability across a wide temperature\nrange from 25 °C down to –80 °C. The comparative charge-discharge profiles are presented in Fig.\nR6a, b. The data clearly shows that while polarization increases as the temperature decreases, a trend\nconsistent with slower kinetics, the cell maintains well-defined and flat discharge plateaus even at the\nextreme temperature of –80 °C. The ability to deliver significant capacity at such a low temperature\nhighlights the effectiveness of the TSSR strategy in enabling robust cryogenic operation.\nFurthermore, the comparison at room temperature reveals the crucial role of our strategy in\nenhancing ambient-temperature stability and kinetics. At a high current density of 2000 mA g⁻1,\nthe long-term cycling data (Fig. R6d) demonstrates that the TSSR electrolyte delivers over 600 stable\ncycles, whereas the baseline electrolyte fails rapidly after approximately 200 cycles. The origin of this\ndivergence is revealed in the charge-discharge profiles at different cycle numbers (Fig. R6c). By the\n200th cycle, the baseline electrolyte cell exhibits a significant voltage drop and increased polarization,\nindicative of severe degradation. In contrast, the profile of the TSSR electrolyte remains almost\nunchanged, confirming its outstanding interfacial stability.\nTaken together, this comprehensive data demonstrates that the TSSR strategy is effective for\nenhancing battery performance across a wide operational window, addressing key stability and kinetic\nchallenges at both ambient and cryogenic temperatures.\nWe have added this new data and corresponding discussion to the revised manuscript, Page 19, Line\n373, Supplementary Fig. 28.\nFig. R6|Comprehensive electrochemical performance at different temperatures. a,b, First\ndischarge (a) and charge-discharge (b) profiles of the TSSR electrolyte at 25 °C, –40°C, and –80 °C at\na current density of 500 mA g⁻1. c, Comparative charge-discharge profiles for baseline electrolyte and\nTSSR electrolyte at the 50th and 200th cycle at 25 °C and 2000 mA g⁻1. d, Corresponding long-term\ncycling performance at 25 °C and 2000 mA g⁻1. The TSSR electrolyte maintains a stable specific\ncapacity of ~500 mAh g⁻1 and nearly 100% Coulombic efficiency for 600 cycles, whereas the baseline\nelectrolyte cell shows rapid capacity fade and erratic efficiency after ~100 cycles.\n6. Fig. S13 (with additive? But the caption says \"without LiOTf\" – is this a labeling error?) shows\nalmost no S. However, the first discharge should generate a large amount of S in cathode due to the\nreduction of SOCl .\n2 2\nHow to explain the disappearance of S? Although S is slightly soluble in SOCl ,\n2\nthe control group (Fig. S11) shows significant sulfur. How to explain this?\nResponse: Thank you very much for pointing out the labeling error in the original caption. To clarify\nthe experimental conditions, all post-cycling cathodes for TOF-SIMS analysis were retrieved after 100\ncycles in a fully discharged state. While the 3D TOF-SIMS reconstruction images (Supplementary Fig.\n11 and 13) are useful for visualizing spatial distribution, they can be misleading regarding quantitative\nsignal intensity, which may have contributed to the impression that sulfur had disappeared.\nTherefore, to provide a more accurate and quantitative comparison, the TOF-SIMS depth profiles\nare presented in Fig. R7. Regarding the sulfur signal difference after 100 cycles, these profiles\ndemonstrate that sulfur (S) does not disappear in the TSSR electrolyte, but its detected amount is\nsubstantially lower. The S⁻ signal intensity in the TSSR cathode (~102 counts) is roughly one order of\nmagnitude lower than in the baseline cathode (~103 counts).\nFig. R7|a, TOF-SIMS depth profiles of key secondary ion signals collected from Li-Cl cathodes after\n2\n100 cycles in baseline electrolyte cell; b, TOF-SIMS depth profiles of key secondary ion signals\ncollected from Li-Cl cathodes after 100 cycles in the TSSR electrolyte.\ninterfacial stability. In the baseline electrolyte, the unstable interface facilitates continuous\ndecomposition of SOCl\n2\nin addition to the reversible Cl\n2\n/LiCl redox. This leads to the accumulation\nof sulfur-containing species (including elemental S) over the 100 cycles, explaining the strong\ncumulative S⁻ signal observed.\nConversely, in the TSSR electrolyte, the stable CEI effectively suppresses this excessive\nelectrolyte decomposition. By preventing the buildup of insulating byproducts (passivation) and\nproviding a kinetically favorable interface, the stable CEI promotes higher electrochemical\nreversibility for sulfur-related redox processes. Although sulfur species are formed during discharge\n(including the initial cycle), the high reversibility ensures that minimal irreversible sulfur accumulates\ncycle after cycle. Consequently, the much lower S⁻ signal after 100 cycles primarily reflects the small\namount of sulfur species involved in the reversible cycling at that stage, rather than a large, irreversible\naccumulation from previous cycles.\nWe have added this new data and corresponding discussion to the revised Supporting Information,\nSupplementary Fig. 11-13, 15 and Supplementary Text. 1.\n7. The scale bars in Fig. S34 are not clear, and the magnifications are inconsistent. This is very\nconfusing.\nResponse: We thank the reviewer for pointing out the presentation issues. As suggested, the figure has\nbeen revised to use consistent magnifications and clear scale bars for all panels (Fig. R8). The revised\npresentation allows for a direct comparison of the cathode surface morphology at different\ntemperatures, revealing the evolution from larger, discrete particles at 25 °C to finer deposits at\ncryogenic temperatures. The updated figure has replaced the original one in the revised Supporting\nInformation.\nWe have added this new data and corresponding discussion to the revised Supporting Information,\nSupplementary Fig. 34.\nFig.R8|SEM images showing the surface morphology of the cathode after 10 cycles in the baseline\nelectrolyte at different temperatures (25°C, –40°C, –80°C). The cells were disassembled at a\ndischarged state for analysis.\n8. The SEM morphology of the cathode at -40°C: Fig. S34 (second row) and Fig. S35b show\nexcessive differences. Is it because they are not at similar cycle numbers? Fig. S36 (SEM morphology\nof cathode with additive) shows excessive differences compared to Fig. S34 and Fig. 4f (which also\nshow morphology with additive). The authors frequently mention \"after cycling\", please specify the\nexact cycle number.\nResponse: Thank you very much for your valuable suggestions and we apologize for the lack of clarity\nin our original figure descriptions. We have revised the manuscript to provide the precise conditions\nfor each characterization.\nFirstly, the SEM images in the original Supplementary Figure S34 (Fig. R8) show the morphology\nof the cathode from baseline electrolyte cells after 10 cycles. In contrast, the image in the original Fig.\nS35b shows the cathode from TSSR electrolyte after 100 cycles. The significant difference in\nmorphology is therefore expected, as it reflects two different systems at different stages of cycling.\nSecondly, the difference between the images in the original Figure S36 and Figure 4f, both from the\nTSSR electrolyte, is due to their different cycle numbers and characterization purposes. Figure 4f\nshows the typical surface morphology after 100 cycles, by which time a uniform and dense CEI has\nformed. In contrast, the image in the original Figure S36 was taken after only 10 cycles from an area\nthat had mechanically fractured during disassembly. This location was selected to expose both the\nnascent CEI and the underlying LiCl particles, making it suitable for demonstrating via elemental\nmapping that the newly forming interface is fluorine-rich.\nAs the reviewer rightly suggested, we have now performed a thorough check of the entire manuscript\nand Supporting Information, and have explicitly stated the precise conditions (cycle number, state-of-\ncharge, etc.) for all characterized samples. We once again thank the reviewer for their careful and\nconstructive feedback, which has helped us significantly improve the clarity of our manuscript.\nWe have incorporated these clarifications into the relevant figure captions and text, Supplementary\nFig. 34-36.\nReviewer #2 (Remarks to the Author):\nIn the manuscript entitled \"Ternary Solvation Sheath Reconfiguration Drives Sustainable Cryogenic\nLi-Cl Batteries\", the authors presented an advancement in Li-Cl batteries by addressing interfacial\n2 2\ninstability at cryogenic temperatures through a Ternary Solvation Sheath Reconfiguration strategy.\nUsing LiOTf as an additive, the authors reconfigure the Li+ solvation environment to form a stable\nfluorine-rich cathode-electrolyte interphase, enabling improved cycling stability. However, the novelty\nand breakthrough are insufficient, and the manuscript can’t meet the high standard of Nature\nCommunications. Some suggestions are listed here for authors to address tricky issues.\nResponse: We thank the reviewer for their time and feedback. In response to the comments regarding\nthe work’s novelty, a more focused perspective on the significant advance our findings represent is\nprovided below.\nRechargeable Li-Cl batteries consistently fail at cryogenic temperatures because conventional,\n2\nelectrode-focused strategies neglect the critical role of Li+ solvation chemistry. This work introduces\na novel Ternary Solvation Sheath Reconfiguration (TSSR) strategy, which leverages OTf– and\nchloroaluminates as a bridge to re-engineer the solvation sheath into a stable, anion-rich structure,\nthereby enabling controllable SOCl decomposition and a precisely engineered interphase. This\n2\nsolvation engineering approach delivers benchmark cryogenic performance, including over 1100\ncycles at –40 °C, which is over 8 times the previously reported longest cycle life (130 cycles) at this\ntemperature (Adv. Mater. 2024, 36, 2307192). The strategy also demonstrates stable operation for over\n100 cycles at –80 °C. (Fig. R10a, d).\n(1). The Core Challenge in Li-Cl Batteries: An Unaddressed Solvation Problem\n2\npolarization elevates operating voltages and accelerates parasitic reactions. While current strategies,\nprimarily focused on cathode host engineering (Joule 2023, 7, 515–528, Angew. Chem. Int. Ed. 2024,\n63, e202315931, Adv. Mater. 2025, 37, 2418990), are almost exclusively confined to room-temperature,\nthe few reported cryogenic studies are limited to modest temperatures like –20 °C (Angew. Chem. Int.\nEd. 2023, 62, e202306789). This failure can be attributed to a critical oversight: neglecting the decisive\nrole of the fundamental solvation chemistry. Specifically, the conventional Li-Cl electrolyte structure\n2\nis dominated by solvent-separated ion pairs (SSIPs), which inherently fail to protect the reactive\nSOCl solvent, leading to its uncontrolled parasitic decomposition at the cathode. This forms an\n2\nunstable, byproduct-laden layer that hinders the reversible Cl /S-Cl redox reactions and directly causes\n2\npoor conversion kinetics at low temperatures. This fundamental solvation problem, and the difficulty\nin rationally tuning this complex ternary system, was largely overlooked in prior work.\nFig.R9|Solvation chemistry of Li-Cl electrolytes. a-d, The MD simulation snapshots and\n2\ncorresponding RDF plots for the baseline electrolyte (1.5M LiAlCl and 0.1M LiFSI in SOCl ) (a, c)\n4 2\nand the TSSR electrolyte (with 0.3M LiOTf added) (b, d). e, f, The NMR spectra of the baseline and\nTSSR electrolytes: 7Li NMR (e) and 27Al NMR (f). g, Raman spectra of pure SOCl , the baseline\n2\nelectrolyte, and the TSSR electrolyte. h, Solvation structure composition in the baseline and TSSR\nelectrolytes. i, Conceptual illustration of the TSSR mechanism. The TSSR mechanism leverages the\nOTf⁻ anion to interact with electrolyte components, reconfiguring the Li+ solvation sheath from a\nsolvent-dominated state to an anion-rich aggregate (AGG) structure and enabling the controlled in-situ\nformation of an anion-derived CEI.\n(2). New Solvation Design for Interfacial Control\nPrior work lacked a strategy to reconfigure the complex ternary (Li+/SOCl /chloroaluminates)\n2\nsolvation. The TSSR strategy is introduced, validated by computation and spectroscopy (Fig. R9). This\napproach uses a functional anion to displace reactive SOCl , fundamentally shifting the structure from\ni). This structural shift (further corroborated by NMR and Raman analyses, Fig. R9e-g) creates a\nreconfigured sheath that directs the in-situ formation of an anion-derived CEI. This engineered\ninterphase represents the first rational design in this specific ternary system aimed at addressing the\nspecific failure modes of the Li-Cl system. By stabilizing the interface, it actively suppresses the\n2\nirreversible decomposition and accumulation of S-Cl species, thereby enhancing S-Cl pathway\nsustainability, and accelerates the Cl →LiCl main reaction kinetics by lowering polarization at\n2\nlow temperatures, thus solving the root cause of traditional interfacial failure.\n(3). Performance Breakthroughs Enabled by the TSSR Strategy\nThe TSSR strategy’s core mechanistic innovation is that it transforms the interphase from an\nuncontrolled decomposition byproduct layer into a rationally designed, functional CEI. This\nadvance, enabled by the reconfigured, anion-rich (OTf⁻ and chloroaluminates) solvation sheath,\ntranslates directly into performance breakthroughs validated under demanding cryogenic conditions\n(Fig. R10). The TSSR electrolyte achieved unprecedented cycling stability, sustaining over 1100 cycles\nat –40 °C. In sharp contrast, the baseline electrolyte began to show capacity decay after ~300 cycles,\nleading to unstable Coulombic efficiency. The 1100 cycles performance represents an 8-times increase\nover the longest cycle life (130 cycles) previously reported for Li-Cl batteries at this temperature\n2\n(Adv. Mater. 2024, 36, 2307192). The strategy also enables stable operation at an extreme –80 °C,\ndelivering over 100 cycles (Fig. R10a, d). This combination of high current density, extreme low-\ntemperature operation, and ultra-long cycle life (Fig. R10b), validates that our mechanism is the key\nto overcoming the impasse where traditional, electrode-focused designs have failed.\nFig.R10|Performance breakthroughs enabled by the TSSR strategy. a, Unprecedented cryogenic\ncycling stability of the TSSR electrolyte at –40°C and 1 A g⁻1. b, Radar plot comparing the key\nperformance indicators of this work against other representative alkali metal-Cl battery systems\n2\nreported in the literature. c, Charging profile at the 900th cycle, highlighting the sustained low\npolarization. d, Cycling performance at an extremely low temperature of –80°C. e, dQ/dV plots\ncomparing the evolution of redox peaks for the baseline and TSSR electrolyte over 500 cycles. f, A\nconceptual illustration summarizing how the TSSR strategy enhances kinetics and stabilizes the\ninterface, leading to superior performance.\nThis response has thus clarified the perspective on the work’s novelty. The limitations of the Li-Cl\n2\nfield, rooted in an electrode-centric view that left the cryogenic problem unsolved, were first outlined.\nFollowing this, the rational solvation engineering (TSSR) strategy was introduced as a fundamentally\ndifferent approach, which is shown to directly enable the unprecedented cryogenic performance.\nWe have added these new figures to the revised manuscript, Fig. 2 and Fig. 5.\n1. Near line 167 of page 9, the authors state that rapid electrolyte decomposition leads to severe\nperformance degradation, including a sharp increase in interfacial resistance. However, the evidence\nprovided in Supplementary Figures 2 and 3 does not adequately support this claim. It is recommended\nthat the authors supplement or clarify this data with additional experiments, such as impedance\nspectroscopy results directly linking electrolyte decomposition to resistance rise, or revise the claim to\nalign with the presented evidence.\nResponse: We thank the reviewer for this constructive comment. Following the reviewer’s suggestion,\nthe Electrochemical Impedance Spectroscopy (EIS) experiments were performed to directly\ninvestigate the impedance evolution during extended cycling.\nFig. R11|Evolution of the interfacial impedance during cycling. Nyquist plots for Li-Cl baseline\n2\nelectrolyte and TSSR electrolyte cells after the 1st cycle at a, 25°C and b, –40°C, and after the 200th\ncycle at d, 25°C and e, –40°C. The insets show the equivalent circuit model used for data fitting. c, f,\nBar charts summarizing the fitted interfacial impedance values after the 1st and 200th cycles,\nrespectively. The results quantitatively demonstrate the severe growth of interfacial resistance in the\nbaseline cell upon cycling, in contrast to the significantly more stable interface in the TSSR electrolyte.\nThe results (presented in the new Fig. R11) provide clear, quantitative evidence. After 200 cycles at\n–40 °C, the baseline electrolyte’s resistance grows dramatically to 2560.9 Ω, over five times higher\nthan the 437.8 Ω of the TSSR electrolyte. A similar trend was observed at 25 °C (882.8 Ω vs 127.4 Ω),\nconfirming that the TSSR strategy maintains a significantly more stable, low-resistance interface.\nThis new figure and the corresponding quantitative discussion have been incorporated into the\nrevised manuscript (Page 9, Line 166 and Page 22, Line 426, Supplementary Fig. 37). We have also\nrevised the original claim in the main text to be accurately supported by this new, direct evidence.\n2. A comparison of polarization at −40°C after 900 cycles is presented in Fig. 5c. However, this\nanalysis is flawed because, as indicated in Fig. 5a, the battery without LiOTf (\"w/o LiOTf\") is severely\ndegraded and no longer functional after 900 cycles. Consequently, the comparison lacks validity and\ndistorts the conclusions.\nResponse: We thank the reviewer for this comment and apologize for the lack of clarity in the original\npresentation of Fig. 5a, which led to this misunderstanding. The long-term cycling plot did not show\nthe full data trace for the baseline electrolyte, making it appear to have failed completely much earlier.\nFig. 5a (Fig. R12) has been updated in the revised manuscript to show the complete 900th cycle\ndata trace for the baseline electrolyte, which clearly shows its capacity fade and erratic Coulombic\nefficiency continuing out to the 900th cycle. To further illustrate this degradation pathway, we have\nalso included a new figure (Fig. R13) showing the detailed galvanostatic charge-discharge profiles at\nboth the 500th and 900th cycles. Therefore, the updated Fig. 5a provides the proper validation for the\ncharge-discharge curve comparison presented in Fig. 5c.\nWe have added the new figure to the revised manuscript and Supporting Information, Fig.5 and\nSupplementary Fig. 39.\nFig.R12|Unprecedented cryogenic cycling stability of the TSSR electrolyte at –40°C and 1 A g⁻1.\nFig. R13|Performance comparison of Li-Cl baseline electrolyte and TSSR electrolyte cells at –\n2\n40°C. a, b, Corresponding galvanostatic charge-discharge profiles at the (a) 500th and (b) 900th cycle.\nThe figure illustrates the degradation pathway of the baseline electrolyte, which is characterized by a\nprogressive increase in charging polarization and capacity loss, in contrast to the exceptional stability\nof the TSSR electrolyte.\n3. The manuscript describes Supplementary Figure 28 as depicting a capacity of approximately 1500\nmAh g-1 and a coulombic efficiency exceeding 99%. However, the actual data appears inconsistent\nwith these values. I strongly advise the authors to re-examine the raw data, correct any errors, and\nensure that the figure labels, captions, and textual descriptions align precisely.\nResponse: We sincerely thank the reviewer for your critical comment. This has been corrected in the\nrevised Supporting Information. To further improve the clarity of this figure (Fig. R14), arrows have\nalso been added to explicitly link the cycling data (circles) to their corresponding y-axis (Specific\ncapacity or Coulombic efficiency). To further support our claims, we have also included the results\nfrom our high-capacity cycling test at 1500 mAh g⁻1 (Fig. R15). This experiment confirms the\nCoulombic efficiency also exceeded 99% under these conditions.\nThe corrected figure can be found in the revised Supporting Information, Supplementary Fig. 28\nand 41.\nFig. R14| Long-term cycling performance at 25 °C. Corresponding long-term cycling performance\nat 25 °C and 2000 mA g⁻1. The TSSR electrolyte maintains a stable specific capacity of ~500 mAh g⁻1\nand nearly 100% Coulombic efficiency for 600 cycles, whereas the baseline electrolyte cell shows\nrapid capacity fade and erratic efficiency after ~100 cycles.\nFig. R15|Cycling stability at a high specific capacity of 1500 mAh g⁻1.The baseline electrolyte and\nTSSR electrolyte’s cycling performance at 25°C and a current density of 2000 mA g⁻1. These cells\ncycling was conducted at a reversible capacity of 1500 mAh g⁻1.\n4. Supplementary Table 4 lists comparative examples but fails to match the cited references\naccurately. Upon review, the descriptions or values in the table do not correspond to the references\nprovided.\nResponse: We thank the reviewer for their careful checking, and we apologize for any\nmisunderstanding the table’s notation may have caused.\nWe have now corrected the table’s reference notation and revised to express its meaning more clearly,\nand all citation numbers now accurately link to the dedicated reference list in the Supporting\nInformation (SI). The corrected table is presented below:\nTable R1. Performance comparison of the Li/Cl @TSSR battery (This work) with representative\nCycle Coulombic Specific\nCurrent Density Cycle\nWork temperatur Efficiency Capacity Refs.\n(mA g-1) Number\ne (℃) (%) (mAh g-1)\nNa/Cl @I 700 800 −20 99 500 SI Ref.2\n2 2\nLi/Cl @Co-NC 500 650 −40 95 500 SI Ref.3\n2\n1000 (-40℃)\nLi/Cl @TSSR 1100/100 −40/−80 99.5/99.6 500/400 This work\n2\n200 (-80℃)\nSupplementary References\n1. Zhou, P., Xiang, Y. & Liu, K. Understanding and applying the donor number of electrolytes in\nlithium metal batteries. Energy Environ. Sci. 17, 8057–8077 (2024).\n2. Feng, W. et al. Iodine-induced self-depassivation strategy to improve reversible kinetics in Na-Cl\n2\nbattery. Nat. Commun. 15, 6904 (2024).\n3. Li, P. et al. Co Single-Atom Catalysis for High-Efficiency LiCl/Cl Conversion in Rechargeable\n4. Yuan, B. et al. Unlocking Reversible Silicon Redox for High-Performing Chlorine Batteries.\nAngew. Chem. Int. Ed. 62, e202306789 (2023).\n5. Zhu, G. et al. Rechargeable Na/Cl and Li/Cl batteries. Nature 596, 525–530 (2021).\n2 2\nWe have updated corrected table in the revised Supporting Information, Supplementary Table 4.\n5. The \"Battery Assembly\" section indicates the use of coin cells (CR 2032) with a 316 stainless-\nsteel casing. Given the well-documented high reactivity of Cl species toward stainless steel, which\n2\ncan accelerate corrosion and compromise cell safety.\nResponse: We thank the reviewer for raising this valid point regarding potential side reactions with\nthe 316-SS casing.\nThe impact of this potential corrosion is considered to be minimal. This approach is based on the\nestablished understanding that porous hosts (Joule 2023, 7, 515–528; J. Am. Chem. Soc. 2022, 144,\n22505–22513) are specifically designed to host and confine the Cl redox reaction. Therefore, most of\n2\nthe Cl is likely consumed in the reversible redox reaction within the cathode pores before\n2\nsignificant diffusion to the steel components can occur.\nTo confirm this experimentally, we performed detailed post-cycling analyses. First, the cells with\nthe TSSR electrolyte were disassembled after 50 and 200 cycles (Fig. R16). The optical\nphotographs show that all stainless-steel components, including the casing and spacers, remain bright\nand metallic, with no visible signs of corrosion or degradation. Furthermore, to detect any non-\nvisible contamination, SEM-EDX analysis was performed on the electrode surfaces after 200\ncycles (Fig. R17). The elemental maps for Fe, Co, and Ni (the primary components of 316-SS) show\nonly negligible, scattered signals on both the anode and cathode surfaces.\nWe have added this new figure and corresponding discussion to the revised manuscript, Page 31,\nLine 606, Supplementary Fig. 51, 52.\nFig. R16|Optical photographs of disassembled coin cell components after cycling. The\ncomponents of the cell with the TSSR electrolyte were retrieved after the 50 and 200 cycles. The\nstainless-steel casing parts and spacers remain bright and metallic, showing no visible signs of\ncorrosion or degradation.\nFig. R17|Post-cycling SEM-EDX analysis of the electrode surfaces. a, SEM image of the anode\nsurface after 200 cycles. b-d, Corresponding EDX elemental maps for Fe, Co, and Ni on the anode. e,\nSEM image of the cathode surface after 200 cycles. f-h, Corresponding EDX elemental maps for Fe,\nCo, and Ni on the cathode. The negligible signals for the primary components of stainless steel on both\nelectrodes indicate that no significant corrosion of the cell casing occurred.\n6. It is recommended that the authors conduct rigorous checks across the manuscript, ensuring\nformatting compliance, optimizing figure resolutions, and standardizing abbreviations, especially in\nthe \"Characterization\" section.\nResponse: We thank the reviewer for the suggestions regarding the manuscript’s presentation.\nFollowing this recommendation, a thorough check of the manuscript and Supporting Information has\nbeen performed.\nSpecifically, the manuscript has been re-formatted to comply with the journal’s guidelines, all\nfigures have been checked and replaced with high-resolution versions where necessary, and all\nabbreviations have been standardized. Particular attention was given to the “Characterization” section\nto ensure all abbreviations are defined at first use and applied consistently.\nThe reviewer’s diligent and constructive feedback has been invaluable in significantly improving\nthe overall quality and professionalism of the manuscript. All of the above-mentioned corrections have\nbeen implemented in the revised version.\nReviewer #3 (Remarks to the Author):\nThis manuscript presents an interesting “Ternary Solvation Sheath Reconfiguration (TSSR)” strategy\nto address the critical challenge of interfacial instability in rechargeable Li-Cl batteries. By\n2\nintroducing LiOTf as a functional additive, the authors demonstrate the rational design of a stable,\nfluorine-rich cathode-electrolyte interphase (CEI) through engineering of the Li+ solvation\nenvironment. The claims are well-supported by a combination of spectroscopic, electrochemical, and\ncomputational analyses. The proposed design on CEI achieved impressive stability of 1100 cycles at -\n40 °C, providing potential applications for energy storage in extreme environments. Overall, the work\nis innovative with high quality. Therefore, I would like to recommend its publication in Nat. Commun.\nafter the following comments and suggestions are addressed.\nResponse: We sincerely thank the reviewer for the positive assessment and supportive comments on\nour manuscript. We are very encouraged that the reviewer finds this work to be innovative and of high\nquality, and we appreciate their recognition of the significance of our TSSR strategy. The following\nvaluable suggestions have been carefully considered and addressed in our point-by-point responses\nbelow. We believe the corresponding revisions have further improved the quality of our manuscript.\n1. The result in Fig. 2h regarding the shift towards AGG structures is noted. The manuscript would\nbenefit from a brief comment in the main text on the theoretical implications of this structural shift for\nLi+ transport dynamics, which can enhance the understandings on solvation chemistry.\nResponse: Thank you very much for this excellent and constructive suggestion. Elaborating on the\ntheoretical implications of the solvation structure provides crucial insight into the superior\nperformance of the TSSR electrolyte.\nThe observed shift from solvent-separated/contact ion pairs (SSIP/CIP) towards aggregate (AGG)\ndominated structures is indeed a key factor governing the Li+ transport dynamics (Fig. R18). In\nconventional electrolytes where Li+ exists primarily in isolated SSIP/CIP configurations, the Li+ ion is\ntypically caged within a relatively rigid solvation shell formed by multiple, strongly coordinating\nsolvent molecules. For Li+ to migrate, it must overcome a significant energy barrier to break free\nfrom this solvent cage, a process known as desolvation. This high desolvation energy fundamentally\nlimits the intrinsic mobility of Li+ and thus the overall ionic conductivity.\nFig. R18|a, b, The MD simulation snapshots of the baseline electrolyte (a) and TSSR electrolyte (b).\nc, Solvation structure composition in Li-Cl with baseline and TSSR electrolytes.\nthis transport limitation. In these aggregates, the Li+ ion is co-coordinated by both solvent molecules\nand multiple anions, creating a more dynamic and flexible coordination environment. Crucially, the\nenergy barrier for a Li+ ion to dissociate from one coordination site and move to an adjacent one within\nthe aggregate is significantly lower than the energy required for full desolvation from a tight solvent\ncage. Essentially, the AGG structures provide a low-energy pathway for Li+ migration by facilitating\na more facile local ion motion. This enhanced intrinsic mobility of Li+ directly translates to higher\nionic conductivity and reduced polarization, which are critical for the high performance observed in\nthe TSSR electrolyte, particularly under demanding cryogenic conditions.\nWe have added the new high-loading data and a brief discussion on the cathode selection to the\nrevised manuscript, Page 13, Line 259, Fig. 2.\n2. The cycling stability in Fig. 5a is a key electrochemical parameter. For improved clarity, the\nauthors should explain the phenomenon of the initial capacity variation within the first ≈50 cycles.\nResponse: Thank you very much for this careful observation and for the suggestion to clarify this\npoint. The initial capacity variation observed within the first ≈50 cycles is indeed an important feature\nand is attributed to the electrochemical formation and stabilization of the Cathode Electrolyte\nInterphase (CEI).\nDuring these initial cycles, the OTf⁻ anion gradually decomposes at the cathode interface to form\nthe protective, fluorine-rich CEI. This is a dynamic process that involves the initial wetting of the\nporous electrode and the electrochemical maturation of the interphase until it reaches a stable, low-\nimpedance state. Once this high-quality CEI is fully established after approximately 50 cycles, it\nprovides a robust and stable interface for all subsequent charge-discharge reactions (Fig. R19).\nThis leads to the exceptionally flat and stable capacity plateau observed for the following 1100 cycles.\nFig. R19| Unprecedented cryogenic cycling stability of the TSSR electrolyte at –40°C and 1 A g⁻1.\nWe have added the new high-loading data and a brief discussion on the cathode selection to the\nrevised manuscript, Page 23, Line 452, Fig. 5.\n3. The authors have summarized the work’s significance. It is suggested that they slightly expand the\ndiscussion on the potential generality of the TSSR strategy for other high-voltage battery systems that\nface similar challenges in electrolyte electrochemical stability.\nResponse: Thank you very much for this excellent, forward-looking suggestion. Highlighting the\npotential generality of our TSSR strategy is indeed important for contextualizing its broader impact.\nThe versatility of the TSSR strategy stems from its fundamental approach: it proactively introduces\na functional species that enters the primary cation’s solvation sheath, where it interacts with the\noriginal solvent molecules and other anions. This interaction reconfigures the solvation sheath’s\ncomposition and energetic landscape, which in turn allows for precise control over the subsequent\ninterfacial decomposition pathway. This is a platform concept applicable to any system where the\nspecies within the cation’s primary solvation shell are the primary contributors to detrimental reactions\nat a high-potential cathode.\nA prominent example is in high-voltage lithium metal batteries. In conventional carbonate\nelectrolytes, Li+ is strongly solvated by the carbonate solvent molecules. These solvent molecules are\nthus “dragged” to the cathode interface within the Li+ solvation sheath, where they become highly\nsusceptible to oxidation. The TSSR strategy would fundamentally interrupt this failure pathway. By\nintroducing a functional salt with a high-HOMO anion, this anion competes with the original solvent\nmolecules to enter the Li+ primary solvation sheath. Once inside, it interacts with the remaining\nsolvent and other anions within this newly formed ternary shell, fundamentally altering the shell’s\nproperties and stability. This reconfigured solvation shell then delivers the functional anion—now an\nintegral and reactive part of the Li+ immediate environment—preferentially to the cathode interface.\nUpon oxidation, it is this anion, not the solvent, that decomposes first to form a stable, inorganic-rich\nCEI, effectively shielding the bulk electrolyte.\nThis principle extends to other chemistries. In lithium-sulfur batteries, performance is dictated by\nthe complex solvation of both Li⁺ and lithium polysulfide (LiPS) anions. A TSSR-like approach, using\nadditives to tune this multi-ion solvation environment, can directly alter the solubility and reactivity\nof LiPS species, thus mitigating the shuttle effect and controlling the interfacial kinetics. Similarly, in\nhigh-voltage dual-ion batteries, a functional additive can reconfigure the cation’s solvation\nenvironment to ensure that a more easily oxidizable “sacrificial” species is always present at the\ngraphite cathode interface, ready to form a protective layer before the bulk electrolyte degrades at\nextreme potentials (~5.0 V vs. Li/Li+).\nWe have added the new high-loading data and a brief discussion on the cathode selection to the\nrevised manuscript, Page 28, Line 559.\n4. Regarding the post-cycling characterizations such as XPS and TOF-SIMS, the authors should\nspecify the state of the cathode and any pre-treatment steps in the Methods section to enhance the\nreproducibility.\nResponse: Thank you very much for this important suggestion regarding our experimental details.\nProviding these specifics is indeed crucial for ensuring the reproducibility of our characterization\nresults, and we apologize for this omission in the original manuscript.\nTo address this point, we have now updated the “Characterization” subsection within the Methods\nsection to include these precise details. For clarity in this response, the added information is as follows:\nall post-cycling cathodes intended for XPS and TOF-SIMS analyses were harvested from cells after a\nspecific number of cycles (e.g., 100 cycles) and consistently disassembled in a fully discharged state.\nPrior to characterization, the retrieved cathodes were gently rinsed with a small amount of high-purity\ndichloromethane (DCM) to remove any residual electrolyte salts and subsequently dried under vacuum\novernight inside an argon-filled glovebox.\nWe have added the new high-loading data and a brief discussion on the cathode selection to the\nrevised manuscript, Page 32, Line 633.\n5. In Methods section, the cathode mass loading is described as ≈2.0 mg cm-2. To enhance the\nreproducibility, the authors should provide a more precise range or an average value with standard\ndeviation for the CMK-3 loading across the tested cells.\nResponse: Thank you very much for this valuable suggestion aimed at improving the precision of our\nexperimental details. Furthermore, since new high-loading experiments were performed, we have\nupdated the Methods section to include both mass loading values used in this study (Fig. R20).\nWe have therefore updated this information in the “Battery Assembly” subsection of the Methods\nsection. The mass loading of the CMK-3 in our cathodes, previously described as ≈2.0 mg cm⁻2, is\nnow specified as 2.0 ± 0.2 mg cm⁻2 and 4.0 ± 0.2 mg cm⁻2.\nWe have added a brief discussion on the cathode selection to the revised manuscript, Page 30, Line\n593.\n6. For better reproducibility of MD simulations, it is highly recommended to provide the exact\nnumber of each type of molecule and ion (SOCl , Li+, AlCl4-, OTf-, etc.) used to construct the\n2\nsimulation box in the Methods section.\nResponse: Thank you very much for this crucial suggestion to enhance the reproducibility of our MD\nsimulations. Providing the exact number of species in the simulation box is a fundamental requirement,\nand we have now added this information to the “Theoretical calculations” part of our Methods section.\nFor complete clarity, the simulation box for the TSSR electrolyte was constructed using 2754 SOCl\n2\nmolecules, 380 Li+ ions, 360 AlCl ⁻ ions, 100 OTf⁻ ions, and 20 FSI⁻ ions. The simulation box for the\n4\nbaseline electrolyte contained 2754 SOCl\n2\nmolecules, 380 Li+ ions, 360 AlCl\n4\n⁻ ions, and 20 FSI⁻ ions.\nWe once again thank the reviewer for their insightful and highly constructive comments. We believe\nthat the revisions made in response to these suggestions have significantly improved the clarity, depth,\nand overall quality of our manuscript.\nWe have added the new high-loading data and a brief discussion on the cathode selection to the\nrevised manuscript, Page 33, Line 652.\nResponse to Reviewers’ Comments\nDear Editors and Reviewers:\nWe would like to greatly appreciate you giving us the opportunity to revise our manuscript.\nWe carefully studied the reviewer’s comments and tried our best to revise the manuscript according\nto the comments. The manuscript has been revised following the comments and suggestions of the\nreviewers, and point by point replies are given below. Thanks again to the editors and reviewers for\ntheir hard work.\nReviewers’ comments:\nReviewer #1 (Remarks to the Author):\nOverall, the additional supporting data and more detailed discussions have improved the manuscript.\nHowever, please address the above issues and further verify the accuracy of all figure captions and\ndata.\nResponse: We appreciate the reviewer’s positive assessment and the recognition that our additional\ndata and discussions have improved the manuscript. We sincerely thank you for identifying the\ninconsistencies in the figure captions. In strict accordance with your instruction, we have conducted a\ncomprehensive verification of all figure captions and experimental data throughout the manuscript to\nensure accuracy. The identified errors have been corrected, and detailed responses to each specific\nissue are provided below.\n1. Figure R2a shows the first-cycle discharge comparison between the TSSR electrolyte with\nadditives and the baseline additive-free electrolyte, both exhibiting a capacity of ~2200 mAh/g.\nHowever, under the same testing conditions, Fig R1a displays different discharge capacities for the\ntwo electrolytes, both exceeding 2500 mAh/g. How can this be explained?\nCould it be due to\ninconsistent cathode loading or other variations in experimental conditions?\nResponse: We thank the reviewer for this keen observation regarding the initial discharge capacity\ndifference. We speculate that this discrepancy could stem from a combination of experimental factors,\nincluding the cathode mass loading and subtle environmental fluctuations during testing.\nRegarding mass loading, the discharge process in Li-Cl batteries is terminated by the surface\n2\npassivation of insulating LiCl (Nature 2021, 596, 525; Adv. Mater. 2024, 36, 202307192). Although\nwe controlled the CMK-3 loading within 2.0 ± 0.2 mg cm⁻2, slight variations within this tolerance\nbetween different batches could contribute to the observed capacity fluctuation. Moreover, ambient\ntemperature stability may be another critical factor influencing the initial discharge capacity. The 25°C\ntests were conducted in an air-conditioned laboratory environment, where minor temperature\nfluctuations are possible. It is worth noting that, compared to the strictly controlled thermal chambers\nused for our low-temperature measurements (which typically show higher consistency), these\nenvironmental fluctuations could slightly influence the electrolyte reaction kinetics, thereby affecting\nthe final discharge capacity.\nIn our future work, we will systematically investigate the specific impacts of LiCl deposition\nbehavior, cathode mass loading, and temperature variations on the initial discharge performance.\n2. In Fig R2b, the blue curve represents the charge-discharge profile of the optimized TSSR\nelectrolyte, showing unstable charging voltage and significantly low Coulombic efficiency (CE).\nWhy\ndoes Fig R2c, in contrast, demonstrate high CE and stable cycling for the TSSR electrolyte?\nThe authors are requested to carefully verify their data. Similarly, in Fig R2e, the blue TSSR curve shows\nlarge polarization and very low CE, yet the cycling performance appears quite good.\nResponse:\nFig. R1|Cycling stability at a high specific capacity, comparing the baseline electrolyte and the\nTSSR electrolyte. a,b, Charge-discharge profiles for the 1st and 100th cycle at 25°C and a current\ndensity of 2000 mA g⁻1. c, Corresponding cycling performance at 25°C. d,e, Charge-discharge profiles\nfor the 1st and 100th cycle at –40°C and a current density of 1000 mA g⁻1. f, Corresponding cycling\nperformance at –40°C. These cells cycling was conducted at a reversible capacity of 1500 mAh g⁻1.\nThe electrolyte volume for each cell was controlled at 100 µL.\nWe thank the reviewer for pointing this out. In the manuscript, we consistently use blue lines to\nrepresent the Baseline electrolyte and pink lines for the TSSR electrolyte. The mismatch in Fig. R1b\nand R1e was an error during the figure labeling process where the legends were inadvertently swapped.\nWe apologize for the confusion and have corrected the legends and colors in the revised manuscript to\nensure they strictly match the cycling data (Fig. R1).\nWe have added this revised figure to the revised Supporting Information, Supplementary Fig. 41.\n3. Please confirm the amount of electrolyte used in each cell, especially for the high-capacity cells\ncycled at 1500 mAh/g. This is critical, as a larger amount of electrolyte typically prolongs battery\nlifespan.\nResponse: We thank the reviewer for this important comment. We confirm that the electrolyte volume\nused in all coin cells, including those for the high-capacity cycling tests shown in Fig. R2, was\ncontrolled at 100 µL, as stated in the “Battery Assembly” section of the Methods. This dosage is\nconsistent with standard protocols in reported Li/Na-Cl battery research (Nat. Commun. 2024, 15,\n2\n7113; Adv. Mater. 2025, 37, 2418990). While increasing electrolyte volume can indeed extend cycle\nlife, our comparative study ensured that both the Baseline and TSSR groups used the exact same\namount. Therefore, the improved performance is attributed to the TSSR strategy rather than an excess\nof electrolyte.\nThis corresponding discussion have been incorporated into the Supporting Information,\nSupplementary Fig. 41.\n4. In Fig R4, doesn't the AC cathode material exhibit smaller polarization than the CMK-3 carbon\nmaterial selected by the authors? Why do the authors consider CMK-3 superior?\nThe specific surface area and pore structure of CMK-3 should also be shown.\nResponse:\nFig. R2|Physical characterization of CMK-3 and electrochemical comparison with activated\ncarbon (AC). a, Nitrogen adsorption-desorption isotherms of CMK-3. The typical Type-IV isotherm\nwith a distinct hysteresis loop confirms the mesoporous nature of the material. Inset values indicate a\nspecific surface area (S ) of 857.5 m2 g–1 and a total pore volume (V ) of 1.04 cm3 g–1. b, Pore\nBET total\nsize distribution curve calculated via the BJH method, showing a uniform mesopore distribution\ncentered at ~4.86 nm. c, Long-term cycling stability comparison between CMK-3 and AC cathodes at\n–40°C and 1000 mA g⁻1. d, Charge-discharge profiles for Li-Cl cells using CMK-3 and AC cathodes\n2\nwith TSSR electrolyte at the 100th cycle, measured at –40°C and 1000 mA g⁻1. The lower overall\npolarization and flatter charging plateau of the CMK-3 cathode, in contrast to the high and rising\ncharging voltage of the AC cathode, highlight the kinetic advantages of the ordered mesoporous\nstructure.\nWe thank the reviewer for this crucial question and we apologize for the misunderstanding and have\ncorrected the figure in the revised manuscript to clarify this point. As shown in the corrected plot (Fig.\nR2d), the curve exhibiting a flatter voltage plateau and lower polarization actually corresponds to\nCMK-3, whereas the curve with a sloping profile and larger polarization corresponds to AC.\nTo further demonstrate the performance advantage of CMK-3, we have added a long-term cycling\ncomparison in Fig. R2c. The CMK-3 cathode maintains exceptional stability for over 500 cycles with\nnegligible capacity decay. In contrast, the AC cathode suffers from rapid failure within 100 cycles.\nThis performance divergence is intrinsically linked to their physical properties.\nAs requested, we have provided the specific surface area and pore size distribution data for the\nCMK-3 used in this work (Fig. R2a, b). The results show that CMK-3 possesses a high specific surface\narea of 857.5 m2 g⁻1. The nitrogen adsorption-desorption isotherm (Type IV) and pore size distribution\nconfirm a well-defined mesoporous structure with an average pore diameter of 4.86 nm. This\nmesoporous architecture is critical for the Li-Cl battery chemistry, as it provides sufficient volume to\n2\naccommodate the solid insulating LiCl discharge product without blocking ion transport channels.\nConversely, activated carbon is typically dominated by micropores, which are easily clogged by LiCl\ndeposition, leading to “dead” active sites and the observed poor reversibility. We hope these additional\ndata and clarifications satisfactorily address your concerns regarding the cathode selection.\nWe have added this revised figure and discussion to the revised Supporting Information,\nSupplementary Fig. 50.\n5. In Fig R6a, how is it possible that the first-cycle discharge capacity and voltage plateau at 25°C\nare significantly lower than those at -80°C?\nResponse: We thank the reviewer’s careful observation. The confusion regarding the performance at\n25°C versus –80°C stems from a misunderstanding of the color coding in the original figure.\nTheoretically, higher temperatures improve electrochemical kinetics, which naturally leads to\nhigher discharge plateaus and capacities.\nTo clarify this temperature dependence and prevent further misunderstanding, we have corrected the\ncolor labels and, more importantly, added new experimental data at –60°C (Fig. R3a, b). The revised\nfigure now clearly shows a continuous trend: as the temperature decreases, the polarization increases\nand the capacity decreases. This aligns well with theoretical expectations.\nWe have added this revised figure to the revised Supporting Information, Supplementary Fig. 28.\nFig. R3|Comprehensive electrochemical performance at different temperatures. a,b, First\ndischarge (a) and charge-discharge (b) profiles of the TSSR electrolyte at 25°C, –40°C, –60°C and –\n80°C at a current density of 500 mA g⁻1. c, Comparative charge-discharge profiles for baseline\nelectrolyte and TSSR electrolyte at the 50th and 200th cycle at 25°C and 2000 mA g⁻1. d,\nCorresponding long-term cycling performance at 25°C and 2000 mA g⁻1. The TSSR electrolyte\nmaintains a stable specific capacity of ~500 mAh g⁻1 and nearly 100% Coulombic efficiency for 600\ncycles, whereas the baseline electrolyte cell shows rapid capacity fade and erratic efficiency after ~100\ncycles.\nFinally, in response to your valuable feedback, we have conducted a comprehensive verification of\nall figure captions and experimental data throughout the manuscript to ensure accuracy. We would like\nto express our special gratitude to you. Your meticulous review and keen observations were\ninstrumental in identifying critical inconsistencies that we had overlooked. Furthermore, the additional\ndata incorporated in this revision has significantly bolstered our conclusions and enhanced the overall\nscientific rigor of the work. We deeply appreciate your constructive approach, which has truly elevated\nthe quality of this manuscript. We hope that these revisions satisfactorily address all your concerns.\nReviewer #2 (Remarks to the Author):\nIn this round of revision, the authors made some efforts to enhance the scientificity and rigor of the\nmanuscript. However, the referee still considers the lack of innovation as a fatal weakness, as it fails\nto make a significant contribution to the Cl battery field, and is difficult to attract the interest of a range\nof readers. Actually, the referee can hardly find any competing innovation of this work on Cl chemistry\nor electrochemistry compared to Many reported papers on Li-So2Cl2 battery. Briefly, the revised\nmanuscript still can not meet the high standards of Nature Communications, and I recommend reject.\nResponse: We thank the reviewer for the feedback but respectfully disagree with the assessment\nregarding the novelty and contribution of this work. First, we must clarify a fundamental distinction.\nThis research focuses on the rechargeable Li-Cl battery (based on Li-SOCl chemistry), not the\n2 2\nLi-SO Cl battery mentioned in the comment. These are two distinct electrochemical systems with\n2 2\ndifferent reaction mechanisms. Confusing them overlooks the specific challenges required to make the\nLi-Cl\n2\nsystem reversible at cryogenic temperatures.\nRegarding the innovation in chlorine chemistry, this work specifically focuses on solvation\nchemistry. We introduce the Ternary Solvation Sheath Reconfiguration (TSSR) strategy to regulate\nthe interaction with aluminum species (chloroaluminates), which are the fundamental chlorine\ncarriers. By reconfiguring the coordination environment of these aluminum species, we effectively\ncontrol the electrochemical pathways of chlorine. This represents a fundamental advancement in the\nelectrochemistry of chlorine-based electrolytes.\nFurthermore, this mechanistic innovation directly enables unprecedented performance, including\nstable rechargeability at –40 °C (1100 cycles) and operation down to –80 °C. To our knowledge, no\nreported papers on Li-SOCl or Li-SO Cl batteries have demonstrated such exceptional low-\n2 2 2\ntemperature cyclability.\nIn summary, by redefining the solvation chemistry of chloroaluminates and achieving benchmark\ncryogenic performance, this work offers distinct and significant contributions to the field of\nrechargeable alkali metal-chlorine batteries. We believe these advances clearly differentiate our work\nfrom existing literature.\nReviewer #3 (Remarks to the Author):\nThe authors have made sufficient revisions according to the reviewers’ comments and suggestions, and\nthe revised manuscript has been significantly enhanced. This work can provide important insights to\nfuture works in the field of rechargeable Li-Cl batteries. Therefore, I would like to recommend its\n2\npublication.\nResponse: We appreciate the reviewer’s positive assessment and recommendation for publication. We\nare glad that the revisions have met the reviewer’s expectations and enhanced the quality of the\nmanuscript.\nResponse to Reviewers’ Comments\nDear Editors and Reviewers:\nWe would like to greatly appreciate you giving us the opportunity to revise our manuscript.\nWe carefully studied the reviewer’s comments and tried our best to revise the manuscript according\nto the comments. The manuscript has been revised following the comments and suggestions of the\nreviewers, and point by point replies are given below. Thanks again to the editors and reviewers for\ntheir hard work.\nREVIEWERS' COMMENTS\nReviewer #1 (Remarks to the Author):\nManuscript can be accepted.\nResponse: We really appreciate you for the positive opinion on our work as well as\nprevious helpful suggestions."}, {"round": 2, "reviewer_comments": {"reviewer_1": "Manuscript can be accepted.", "reviewer_2": "In this round of revision, the authors made some efforts to enhance the scientificity and rigor of the manuscript. However, the referee still considers the lack of innovation as a fatal weakness, as it fails to make a significant contribution to the Cl battery field, and is difficult to attract the interest of a range of readers. Actually, the referee can hardly find any competing innovation of this work on Cl chemistry or electrochemistry compared to Many reported papers on Li-So2Cl2 battery. Briefly, the revised manuscript still can not meet the high standards of Nature Communications, and I recommend reject.", "reviewer_3": "The authors have made sufficient revisions according to the reviewers' comments and suggestions, and the revised manuscript has been significantly enhanced. This work can provide important insights to future works in the field of rechargeable Li-Cl2 batteries. Therefore, I would like to recommend its publication."}, "author_response": "Response to Reviewers’ Comments\nDear Editors and Reviewers:\nWe would like to greatly appreciate you giving us the opportunity to revise our manuscript.\nWe carefully studied the reviewer’s comments and tried our best to revise the manuscript according\nto the comments. The manuscript has been revised following the comments and suggestions of the\nreviewers, and point by point replies are given below. Thanks again to the editors and reviewers for\ntheir hard work.\nREVIEWERS' COMMENTS\nReviewer #1 (Remarks to the Author):\nManuscript can be accepted.\nResponse: We really appreciate you for the positive opinion on our work as well as\nprevious helpful suggestions."}, {"round": 3, "reviewer_comments": {"reviewer_1": "Manuscript can be accepted."}, "author_response": ""}]

Decision letter