Amorphous/crystalline interwoven multipods with high Co/Ni activity for wide-temperature-range sodium-sulfur batteries

Domain: biology
Published: 2026-03-10
Editorial outcome: minor_revision

Abstract
Sluggish kinetics caused by 16-electron transfer hinders development of wide-temperature-range sodium-sulfur batteries. Here we report Sn-doped CoNiS multipods with an amorphous-crystalline interwoven structure. Employed as a positive electrode catalyst, the resulting sodium–sulfur battery exhibits a discharge capacity of 1320.8 mAh g−1 at 3 Ag−1 after 1200 cycles at room temperature, together with stable and high-capacity electrochemical performance ranged from −20 to 50 °C. It has been evidenced that the amorphous/crystalline interfaces generated by Sn doping can adjust the microelectronic environment of Co and Ni atoms, optimize their adsorption energy toward sodium polysulfide intermediates through Co–S and Ni–S bonding, and thus decrease the energy barrier of polysulfide conversion. This interfacial regulation efficiently lowers the energy barrier of the rate-determining step and facilitates the overall reaction kinetics over a wide temperature range. This work provides an efficient amorphous/crystalline interface engineering strategy to develop high-performance catalysts.

Introduction
As an emerging type of low-cost sodium secondary batteries, sodium-sulfur (Na||S) battery uses sulfur as positive electrode and metallic sodium as negative electrode. The sulfur electrode involves a complex 16-electron conversion between chemical energy and electrical energy during charging and discharging processes, which endow the battery high capacity1,2. However, the sluggish kinetics associated with the complex multi-electron process and the shuttle effect caused by soluble intermediates of polysulfides cause significant challenges, resulting in low battery capacity, rapid capacity decay, and insufficient energy and power densities3. As for the batteries running at room temperature, some sulfur host materials with catalytic effect in sulfur electrodes were prepared, such as 3D carbon matrix, TiC quantum dots supported on carbon nanotubes (CNTs), and a few transitional metal sulfides, to obtain considerable specific capacities and cycle life4–6. Considering the greenhouse effect and extreme weather we are facing, it’s crucial to develop all-climate wide-temperature-range batteries to meet the needs of operation in multiple regions and all seasons. It is worth mentioning that the sodium ion diffusion and the conversion process of sodium polysulfides (NaPSs) can be dramatically reduced at low (sub-zero) temperatures, which lead to polarization and limited discharge capacity. It has been reported that the Na+ diffusion rate drops by ~70% and the capacity drops by ~30% when the operating temperature decreases from 25 to −20 °C7–9, showing a significant reduction and slowdown of the kinetic rate due to low temperature. Referring to higher temperatures above 40 °C especially at high specific currents, Na||S batteries suffer from accelerated capacity decay and shortened lifespan because of the exacerbated shuttle effect10,11. Although the room-temperature positive electrode catalysts in Na||S batteries have made some progress, it remains a great challenge to develop wide-temperature-range catalysts with further enhanced adsorption properties and catalytic activity.

Transition metal sulfides have been proven to be efficient catalysts for metal−sulfur batteries12. In particular, the unique electronic structure of cobalt enables a balance between polysulfide adsorption and conversion, ensuring stable catalytic activity over a wide temperature range13–15. For example, Dou and his coworkers used cobalt sulfide as an electron reservoir to enhance the activity of the sulfur positive electrode of Li||S batteries, enabling sulfur to be directly reduced to short-chain lithium polysulfides through a simplified redox pathway16. Interface engineering can be one feasible strategy to further promote the catalytic and adsorption performances towards polysulfides17,18. Among different interface types, the amorphous/crystalline interface could be an ideal structure for Na||S batteries. It combines the advantages of both phases, including the high conductivity and structural stability of crystalline regions as well as the abundant active sites and strong adsorption capacity of amorphous regions17–21. For instance, Lee et al. constructed a nanoscale crystalline–amorphous MoO3 heterostructure, which facilitated continuous adsorption and conversion of lithium polysulfides, leading to high sulfur utilization and stable cycling behavior19. Moreover, Liu et al. demonstrated that a crystalline–amorphous Ni2P/CeO2 heterostructure with strong interfacial electronic interaction could accelerate Li2S deposition/decomposition kinetics and improve long-term cycle life20. Considering better electron transfer enabled by the crystalline structure, interwoven amorphous and crystalline structures containing metal sulfides could have great potential for developing suitable catalysts. Traditionally, amorphous structure can be obtained by low-temperature reaction, rapid cooling treatment, and reduction atmosphere growth4,17,18,22. Besides addressing the low-temperature kinetics, high-temperature anti-shuttle performance needs to be considered as well. Supported catalysts could be a good choice. On one hand, the substrate with high specific surface area can disperse metal sulfides, serve as a sulfur host, and provide more active sites during the electrocatalytic process. On the other hand, it can afford suitable adsorption energy, suppressing the dissolution and the shuttle effect of the intermediates of NaPSs.

Based on these factors, this work applied Sn doping to interfere with the crystal growth of CoNiS and thus synthesized CoNiS multipod-like structure with amorphous/crystalline interface (A/C-CoNiS) using two-dimensional (2D) MXene sheets as substrate. After loading sulfur, the as-prepared sample was used as both a catalyst and an adsorbent in wide-temperature (all-weather) Na||S batteries. At room temperature, it exhibits a high discharge specific capacity of 1320.8 mAh g−1 after 1200 cycles at 3 Ag−1 with a decay rate of 0.012% per cycle. At −20 °C, it shows a high discharge capacity of 949.9 mAh g−1 after 400 cycles, even at a high specific current of 2 Ag−1. At 50 °C, it maintains stable cycling performance, with a capacity decay rate of only 0.001 % per cycle over 700 cycles. Control experiments, electrochemical measurements, and density functional theory (DFT) calculations provided solid evidence to confirm the role of amorphous/crystalline interfaces generated by Sn doping in optimising adsorption energy towards intermediates and decreasing the energy barrier of NaPSs conversion, which then boosts kinetics and mitigates the shuttle effect for wide-temperature-range batteries.

Results
Synthesis and characterization of multipod-like A/C-CoNiS catalyst
Figure 1a illustrates a typical synthesis route for preparation of A/C-CoNiS grown on Ti3C2Tx MXene. The characterizations of Ti3C2Tx MXene were shown in Supplementary Fig. 1. Because of having negatively charged surfaces, MXene can easily adsorb Co2+, Ni2+, and Sn2+ ions via electrostatic interaction. By adding hydrazine and heating, Co0.5Ni0.5Sn(OH)6 nanocrystals were then formed on MXene, serving as the precursor inducing the growth of multipod structure (Supplementary Fig. 2). A/C-CoNiS was finally produced through sulfurization process (Supplementary Fig. 3). It’s interesting to find that Sn introducing not only induces the formation of unique multipod structure, but also leads to the interwoven crystalline and amorphous structure. Figure 1b shows the high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM) image of several A/C-CoNiS multipods. Figure 1c shows a uniform distribution of Co, Ni, S, and Sn elements in one typical particle. The Sn content is very low, which was further verified by ICP-AES (molar ratio, Co:Ni:Sn = 1:0.9:0.1, Supplementary Table 1). The selected-area electron diffraction (SAED) pattern was selected from the branch tip in Fig. 1c confirms the single-crystal nature of the branch. The atomic image in Fig. 1d reveals the coexistence of amorphous (red frame) and crystalline (blue frame) phases within A/C-CoNiS. The lattice fringes well match the crystal structure of (CoNi)9S8 with spacings of 0.22 nm corresponding to the (331) planes of (CoNi)9S8. To better understand the structure, TEM and HRTEM images in Fig. 1e combined with Supplementary Fig. 4 disclose that the branches of the particle are assembled by many directional-growth single-crystal thin rods, in agreement with the SAED result. The right HRTEM image clearly exhibits the amorphous structure and neighboring (311) crystal planes of (CoNi)9S8, revealing that A/C-CoNiS particles were composed of some single-crystal branches dispersedly decorated by amorphous grains. Those single-crystal thin rods might provide faster electron transfer during catalytic process17,26, while the amorphous phase could provide more active sites for NaPSs conversion25. Additionally, three other transition metals (Cu, Mn, and Zn) were selected for doping, but no comparable effects were observed (Supplementary Figs. 5–7). To confirm the importance of amorphous/crystalline interfaces, we synthesized crystalline CoNiS (C-CoNiS) for comparison with characterizations in Supplementary Fig. 8. Compared with C-CoNiS, the ratio of Co2+/Co3+ increases from 1.5:1 to 1.9:1 while Ni2+/Ni3+ increases from 0.7:1 to 1.2:1 (Fig. 1f and Supplementary Fig. 9). The reduced chemical valence state of Co and Ni demonstrates the effect of Sn doping on adjusting the electronic microenvironment of Ni and Co atoms. Figure 1g shows that A/C-CoNiS has a stronger electron paramagnetic resonance (EPR) signal at g=2.003, indicating the sample has more sulfur vacancies27. That also explains why Ni and Co of A/C-CoNiS show decreased valence states to meet the charge balance. That is, we generated more sulfur vacancies by Sn doping because of partial amorphization of CoNiS. In addition, nitrogen adsorption–desorption analysis confirms that A/C-CoNiS possesses a larger surface area and a mesoporous structure (~3.9 nm), which facilitates electrolyte infiltration and ion diffusion (Supplementary Fig. 10).

Na||S battery performances operated from −20 to 50 °C
The coin cells with A/C-CoNiS/S and C-CoNiS/S electrodes were tested within a voltage window of 0.2~2.8 V. Supplementary Fig. 11 shows that A/C-CoNiS/S achieves its optimal electrochemical performance at a sulfur loading of 70 wt%, while the maximum sulfur loading of C-CoNiS/S is 65 wt%. Figure 2a shows the galvanostatic charge-discharge (GCD) profiles of A/C-CoNiS/S and C-CoNiS/S electrodes. The discharge curve of A/C-CoNiS/S exhibits three voltage plateaus at ~2.0, 1.5, and 0.8 V, corresponding to the conversion from S8 to long-chain polysulfides (Na2Sx, 6 < x ≤ 8), then to Na2S4, and finally to Na2S. Upon charging, two main plateaus appear at 1.7 and 2.2 V, corresponding to the stepwise oxidation of Na2S to Na2S4 and then to Na2S8. As marked, the voltage difference (ΔE) between charge and discharge platforms is 0.92 V for A/C-CoNiS/S, much lower than 1.28 V of C-CoNiS/S, indicating better reversibility29. Compared with C-CoNiS/S, both longer discharge plateaus and decreased ΔE of A/C-CoNiS/S also reveal a faster kinetic rate. A/C-CoNiS/S exhibits a discharge capacity of 1444.4 mAh g−1 and an initial coulombic efficiency of 98.9 % at the specific current of 1 Ag−1, higher than that of C-CoNiS/S (799.9 mAh g−1). It indicates that the amorphous/crystalline structure provides a better catalytic effect and thus effectively enhances the utilization rate of sulfur. In Fig. 2b, A/C-CoNiS/S shows a high capacity of 1437.6 mAh g−1 after 250 cycles at 1 Ag−1 with a capacity decay of 0.002 % per cycle and a nearly 100 % coulombic efficiency. By contrast, C-CoNiS/S only achieves a discharge capacity of 730.4 mAh g−1 with a capacity decay of 0.035 % per cycle. Supplementary Fig. 12a shows that the sodium-ion storage performance of A/C-CoNiS contributes minimally to the overall capacity, indirectly indicating that the main contribution comes from the redox process of sulfur. The MXene/S and Ketjen Black/S electrodes deliver capacities far below A/C-CoNiS/S, highlighting the catalytic advantage of A/C-CoNiS (Supplementary Fig. 12b, c). Even though we increased the sulfur loading to 3 mg cm−2, A/C-CoNiS/S can still give a capacity of 523.2 mAh g−1 after 400 cycles at 1 Ag−1 and a nearly 100 % coulombic efficiency in Fig. 2c, comparable to previously reported values (306~373 mAh g−1)17,30,31. Only one close capacity (529.6 mAh g−1) can be found with sulfur loading of 3 mg cm−2, but obtained at a lower specific current (0.84 Ag−1)32. The A/C-CoNiS/S electrode maintains a discharge capacity of 1146.9 mAh g−1 after 50 cycles at 0.2 Ag−1 with an E/S ratio of about 10 μL mg−1 (Supplementary Fig. 13). Figure 2d–f show favorable rate performances of A/C-CoNiS/S. All GCD profiles display similar and distinct plateaus without significant capacity decay in Fig. 2d, indicating favorable rate performance and rapid kinetic rate of NaPSs conversion. C-CoNiS/S in Supplementary Fig. 14 exhibits inferior performance with obvious capacity decay even at 5 Ag−1. Furthermore, A/C-CoNiS/S in Fig. 2e delivers high specific capacities of 1462.8, 1431.6, 1388.1, 1369.6, 1321.4, and 1276.2 mAh g−1 at 0.5, 1, 2, 3, 4, and 5 Ag−1, respectively. Even when the specific current decreases to 0.5 Ag−1, the capacity can still be up to 1490.3 mAh g−1, indicating reversible electrochemical behavior and stable cycling. All these values are significantly higher than those of C-CoNiS/S, indicating that amorphous/crystalline interface improves the rate performance by optimizing reaction kinetics. Deduced from the comparison in Fig. 2f, A/C-CoNiS/S shows improved rate performances with high specific capacities, which are competitive with most reported Na||S batteries3,12,17,28,33–38. The A/C-CoNiS/S electrode in Fig. 2g delivers a high capacity of 1320.8 mAh g−1 at 3 Ag−1 after 1200 cycles with a capacity decay rate of 0.012 % per cycle and a nearly 100 % coulombic efficiency. The above battery data were obtained from three independent parallel tests to ensure reproducibility (Supplementary Fig. 15). The overall battery performance of Fig. 2g was improved compared to the counterparts in Fig. 2h, covering specific capacity at certain cycle rate after cycling, cycle number, cycle rate, capacity retention per cycle, and coulombic efficiency14,15,17,32,39. Many previously reported batteries exhibit final capacities below 700 mAh g−1 at specific currents lower than 3 Ag−115,17,32,39–41. More details can be found in Supplementary Table 2. The radar plot highlights the competitive specific capacity and rate capability of our sample in comparison with reported batteries.

Given the extreme temperatures in real environments, the electrochemical performance tests were conducted at −20 °C and 50 °C to further confirm the boosted reaction kinetics and the mitigated shuttle effect of A/C-CoNiS. First, we carried out low-temperature tests to check the kinetics. Figure 3a shows the change of cyclic voltammetry (CV) peaks between room temperature (25 °C) and low temperature (−20 °C). As for the selected oxidation peak of O2 (Na2S → Na2S2), it’s clear that decreased temperature only makes A/C-CoNiS/S slightly shift by 0.09 V while making C-CoNiS/S shift more positively by 0.20 V, indicating A/C-CoNiS provides a much easier conversion process for NaPSs at low temperatures. The CV curves at 25 °C and −20 °C were shown in Fig. 4a and Supplementary Fig. 16. Figure 3b shows the rate performance of A/C-CoNiS/S at −20 °C. The A/C-CoNiS/S electrode delivers high specific capacities of 1081.4, 1027.6, 936.6, 889.1, 861.0, and 828.6 mAh g−1 at specific currents of 0.5, 1, 2, 3, 4, and 5 Ag−1, respectively. When the specific current restores to 0.5 Ag−1, the discharge capacity can still be up to 1051.1 mAh g−1 with almost no capacity loss. For comparison, the capacity of C-CoNiS/S decreases dramatically at 2 Ag−1, showing no future application in low-temperature batteries. The comparison of GCD curves of A/C-CoNiS/S and C-CoNiS/S electrodes in Supplementary Fig. 17 also confirms the reliable low-temperature performance of A/C-CoNiS. Besides, A/C-CoNiS/S shows almost the same GCD curves at 0 °C, −10 °C, −20 °C, and −30 °C in Supplementary Fig. 18a, revealing its practical application covering a wide low-temperature range. A/C-CoNiS/S gives high specific capacities of ~2.5 times for C-CoNiS/S at the same low temperature (Supplementary Fig. 18b), supporting an enhanced reaction kinetics of A/C-CoNiS compared with C-CoNiS at low temperatures. A/C-CoNiS/S provides a high capacity of 949.9 mAh g−1 after 400 cycles at 2 Ag−1 at −20 °C in Fig. 3c, with a capacity decay rate of 0.001 % per cycle and coulombic efficiency of 99.6 %. By contrast, C-CoNiS/S delivers 510.1 mAh g−1 after 150 cycles at 1 Ag−1 with a decay rate of 0.096 % per cycle. All the above results confirm the competitive low-temperature performance of A/C-CoNiS, including specific capacity, rate performance, and cycling stability.

Then we studied the high-temperature performance of A/C-CoNiS/S. As shown in Fig. 3d, the A/C-CoNiS/S electrode exhibits discharge capacities of 1580.5, 1624.6, and 1652.7 mAh g−1 at 30 °C, 40 °C, and 50 °C at 1 Ag−1, respectively. The high capacity can be attributed to the contribution from increased temperature and the catalytic effect. The stability and high capacity of A/C-CoNiS/S were also confirmed over 30–50 °C in Supplementary Fig. 19. As is well known, increased electron transfer and ionic migration rates at high temperatures promote polysulfide migration, dissolution, and shuttling, thereby deteriorating electrochemical stability. Thus, we need to check its cycling stability. Figure 3e shows that A/C-CoNiS/S gives an initial specific capacity of 1422.7 mAh g−1 at 2 Ag−1, which slightly decreases to 1409.3 mAh g−1 after 700 cycles with an average capacity decay rate of 0.001 % per cycle at 50 °C. For comparison, C-CoNiS/S gives an initial discharge capacity of 839.7 mAh g−1 with an 88.3 % retention rate after 120 cycles. The sudden capacity loss of C-CoNiS/S might be caused by a short circuit influenced by the shuttle effect in the battery at high temperatures. The above battery data were obtained from three independent parallel tests to ensure reproducibility (Supplementary Fig. 20). When compared with reported limited Na||S batteries and even Li||S batteries at a wide-temperature range, our sample of A/C-CoNiS/S in Fig. 3f exhibits a competitive balance between capacity retention and rate capability11,42–45. More details can be found in Supplementary Table 3. The overall performance includes low-temperature specific capacity of 949.9 mAh g−1 at 2 Ag−1 after 400 cycles, as well as high-temperature specific capacity of 1409.3 mAh g−1 at 2 Ag−1 after 700 cycles with a low decay rate of 0.001 % per cycle. All the above experiments and calculations evidently confirm that A/C-CoNiS can afford a faster kinetic rate of polysulfides conversion even at low temperatures and better anti-shuttle effect even at high temperatures. The significant improvement in this material is due to the amorphous/crystalline structure induced by Sn doping.

Improved catalytic reaction kinetics and adsorption energy
The faster kinetic rate guarantees higher capacities, better reversibility and rate performance, while the improved adsorption energy can mitigate the shuttle effect and prolong lifespan. Figure 4 then demonstrates improved kinetic rate and adsorption energy of A/C-CoNiS by electrochemical tests, adsorption experiments, and simulated calculations. The CV curves in Fig. 4a display a series of well-defined reduction and oxidation peaks. Four distinct reduction peaks are observed at 1.97 (R0), 1.53 (R1), 1.17 (R2), and 0.81 V (R3), corresponding to the stepwise conversion of S8 to Na2Sx (R0), Na2Sx to Na2S4 (R1), and Na2S4 to Na2S (R2, R3)16,36. In addition, two peaks at 0.94 V (RM1) and 0.50 V (RM2) are ascribed to Na+ insertion into CoNiS46. The oxidation peaks at 1.30 (OM1), 1.54 (O2), 1.72 (O3), and 2.15 V (O4, M2) correspond to the reverse process accordingly34. Deduced from the peak area, the charge capacity of A/C-CoNiS mainly comes from the conversions from Na2Sx to Na2S4 and from Na2S4 to Na2S. Compared to C-CoNiS/S, A/C-CoNiS/S exhibits higher specific current and lower polarization, indicating that the amorphous/crystalline interfaces generated by Sn doping effectively boost conversion kinetics of NaPSs16,47. The evolution of the CV curves during the initial cycles is shown in Supplementary Fig. 21. Besides, we also used CV tests on symmetric cells in Fig. 4b and electrochemical impedance spectroscopy (EIS) analyses in Supplementary Fig. 22 to confirm the advantage of A/C-CoNiS in catalytic reaction kinetics. Compared to C-CoNiS, A/C-CoNiS exhibits a narrower voltage gap between oxidation and reduction peaks as well as higher current responses, indicating that A/C-CoNiS has much enhanced kinetic rate of NaPSs conversion28,48. In Supplementary Fig. 22, the Rct value of A/C-CoNiS/S is 8.1 Ω, much lower than that of C-CoNiS/S (19.8 Ω), indicating its faster charge transfer16,49. In situ EIS tests and corresponding distribution of relaxation times (DRT) analyses were conducted at 25 and −20 °C to evaluate the electrochemical catalytic performance across the full working voltage range (Fig. 4c–f, Supplementary Fig. 23). The time constant (τ) represents the relaxation time of each electrochemical process. As shown in Fig. 4c–f, each contour plot can be divided into four regions corresponding to interphase contact resistance (R1), charge transfer resistance (R2, Rct), polysulfide diffusion resistance (R3), and ion diffusion resistance (R4)34. At 25 °C, the A/C-CoNiS/S electrode consistently exhibits lower Rct than C-CoNiS/S (Fig. 4c and d). This trend becomes more pronounced at −20 °C (Fig. 4e and f), indicating the enhanced catalytic activity of A/C-CoNiS/S at low temperatures. The much-enhanced kinetic process explains high capacity of batteries running at room temperature and low temperatures. Then we carried out adsorption calculations and tests to confirm the anti-shuttle effect and long-term stability at high temperature. DFT calculations in Fig. 4g indicate strong adsorption of MXene towards NaPSs, which might increase the anti-shuttle effect even at high temperatures. Figure 4h shows that A/C-CoNiS exhibits a markedly weaker UV–vis absorption signal than C-CoNiS and the Na2S6 solution at room temperature, revealing stronger adsorption ability. Quantitative UV–vis adsorption tests (Supplementary Figs. 24 and 25, Table 4) confirm that A/C-CoNiS exhibits greater adsorption capacities especially at high temperatures, indicating an improved anti-shuttle effect. The inserted image shows the obvious color change from yellow to transparent solution by efficient adsorption. The molar ratio of Co3+/Co2+ from A/C-CoNiS increases from 0.5 to 1.0 after adsorbing Na2S6 in Fig. 4i. Similarly, the molar ratio of Ni3+/Ni2+ from A/C-CoNiS increases from 0.8 to 1.4 after adsorbing Na2S6 in Supplementary Fig. 26. The increased oxidation state of Co and Ni elements means the formation of more Co−S and Ni−S bonds with S element from NaPSs. That means the adsorption sites for NaPSs might be Co/Ni atoms. Hence, the as-prepared A/C-CoNiS with amorphous/crystalline interface can provide optimized adsorption energy, which can effectively alleviate the shuttle effect and guarantee the performance at high temperatures.

Finally, we analyzed the influence of amorphous/crystalline interface in A/C-CoNiS on catalytic reaction kinetics by DFT calculations. As shown in Fig. 5a, the atomic structure covers two parts: the amorphous structure (marked with Amor-A/C-CoNiS) generated by Sn doping, and the side parts with crystalline structure (Cryst-A/C-CoNiS). Figure 5b shows the model of C-CoNiS with only crystalline structure for comparison. Because there are two parts in Fig. 5a, we had to select active sites from both amorphous and crystalline regions. Specifically, we screened multiple possible sites and identified the one with the lowest S8 adsorption energy as the optimal active site (Supplementary Figs. 27–29). As shown in Fig. 5c, d, the rate-determining step from Na2S2 to Na2S shows a free energy value of 0.36 eV for C-CoNiS, which decreases to 0.25 eV for Amor-A/C-CoNiS and 0.27 eV for Cryst-A/C-CoNiS. That is, not only the amorphous region (Fig. 5c) but also the nearby crystalline region (Fig. 5d) in A/C-CoNiS exhibit a lower energy barrier for NaPSs conversion. As shown in Fig. 5e, f, the climbing-image nudged elastic band (CI-NEB) calculations reveal that the decomposition barrier of Na2S is significantly reduced from 0.77 (C-CoNiS) to 0.58 eV (Amor-A/C-CoNiS) and 0.68 eV (Cryst-A/C-CoNiS). The structural evolution of Na2S decomposition is provided in Supplementary Fig. 30. Both the amorphous regions and the neighboring crystalline regions of A/C-CoNiS facilitate Na2S decomposition by lowering the energy barrier50. These studies verify that the amorphous/crystalline interface generated by Sn doping optimizes both the local electronic microenvironment of metal sites in both amorphous and crystalline regions.

The battery performance, especially high capacity at low temperature and room temperature, could be ascribed to the optimized catalytic reaction kinetics by amorphous/crystalline interface in A/C-CoNiS. Besides kinetics, the performance at room temperature and at higher temperatures can also be influenced by the adsorption ability of A/C-CoNiS towards intermediates during the charging/discharging process, which mitigates the shuttle effect and guarantees good running of the battery. The improved adsorption energy of A/C-CoNiS towards NaPSs was then confirmed. Figure 5g displays atomic structure model of A/C-CoNiS adsorbing a series of NaPSs and S8. The atomic structure and adsorption models for Cryst-A/C-CoNiS and C-CoNiS are shown in Supplementary Figs. 31, 32. Figure 5h compares the adsorption energies of A/C-CoNiS and those of C-CoNiS towards S8 and catalytic intermediates. All red and yellow bars are higher than the blue ones, indicating that Amor-A/C-CoNiS and Cryst-A/C-CoNiS exhibit stronger anchoring and trapping abilities for NaPSs. Figure 5i presents the differential charge density of S8 on different substrates. The stronger charge transfer between A/C-CoNiS and S8 indicates enhanced adsorption capacity51. In a word, A/C-CoNiS shows better adsorption capacity in inhibiting the shuttle effect of soluble NaPSs, and thus gives more stable and longer lifespan of all-weather Na||S batteries.

In summary, Sn-doped CoNiS multipods grown on 2D Ti3C2Tx MXene have been successfully synthesized. Partial Sn doping generated amorphous regions in CoNiS, forming interwoven amorphous/crystalline interfaces. After sulfur loading, the A/C-CoNiS/S electrode shows all-weather favorite overall battery performance especially its high capacity, compared to its counterpart CoNiS/S with only crystalline structure. At room temperature, it achieves a discharge capacity of 1320.8 mAh g−1 at 3 Ag−1 after 1200 cycles with a decay rate of 0.012% per cycle. At −20 °C, it delivers 949.9 mAh g−1 at 2 Ag−1 after 400 cycles. At 50 °C, it maintains a reversible capacity of 1409.3 mAh g−1 at 2 Ag−1 after 700 cycles with a decay rate of only 0.001 % per cycle. Electrochemical tests, adsorption experiments, XPS characterizations, and DFT calculations confirm the capacities and considerable lifespan could be ascribed to the improved catalytic reaction kinetics and mitigated shuttle effect by improved adsorption ability towards intermediates of sodium polysulfides using the catalyst of A/C-CoNiS. Because the amorphous/crystalline structure can adjust the microelectronic environment of Co and Ni atoms, optimizing adsorption of sodium polysulfides through Co−S and Ni−S bonding, and thus lowering the energy barrier for polysulfide conversion. Moreover, in situ EIS and corresponding DRT analysis verify that A/C-CoNiS effectively accelerates reaction kinetics, particularly under low-temperature conditions. DFT calculation confirms the amorphous/crystalline interface can optimize the rate-determining step of Na2S2 to Na2S evidenced by lowering barrier from 0.36 to 0.25 eV (amorphous part in A/C-CoNiS/S) and to 0.27 eV (crystalline part in A/C-CoNiS/S). The amorphous/crystalline interface engineering via element doping provides an efficient strategy for developing suitable catalyst for sulfur electrode in high-capacity and wide-temperature-range Na||S batteries.

Methods
Synthesis of A/C-CoNiS and C-CoNiS
The A/C-CoNiS sample was synthesized by a wet chemical method. First, 0.5 mmol CoCl2·6H2O (Aladdin, 99 %), 0.5 mmol NiCl2·6H2O (Aladdin, 99 %), 0.05 mmol SnCl2 (Aladdin, 99 %), and 500 mg PVP (Alfa, Mw = 58,000) were dissolved in 100 mL of ethylene glycol (EG, Guangfu, 99.5 %) in a three-neck flask. Subsequently, 10 mg of MXene (JiNan SCMXene Tech. Co., Ltd, 99 %) was added to the solution. After stirring, 2 mL of N2H4·H2O (Aladdin, 80 %) was introduced. The mixture was heated to 170 °C in an oil bath with vigorous stirring. After 1.5 h, 40 mL of CH4N2S (Aladdin, 99 %) solution (4 mmol in EG) was added dropwise, and the flask was kept at that temperature for 2 h. The mixture was then naturally cooled to room temperature, and the resulting black precipitate was washed with ethanol and deionized water by centrifugation (9000 × g) several times. Finally, the powder was stored for use after freeze-drying for 24 h. For comparison, the control sample of C-CoNiS was prepared using the same procedure without addition of SnCl2 and MXene.

Material characterizations
HAADF-STEM imaging was performed using a Cs-corrected FEI Spectra 300 microscope equipped with dual spherical aberration correctors at an accelerating voltage of 300 kV. SEM images were acquired on a FEI Quanta 250FEG field-emission scanning electron microscope operated at an accelerating voltage of 10 kV. XPS measurements were conducted on a Shimadzu/Kratos AXIS SUPRA+ system with monochromatic Al Kα radiation (hν = 1486.6 eV). Pristine samples were prepared and transferred under ambient conditions, whereas polysulfide-adsorbed samples were handled and transferred under an argon atmosphere. Binding energies were calibrated using the C 1s peak at 284.8 eV. XRD patterns were recorded on a Shimadzu XRD-6000 diffractometer with Cu Kα radiation (λ = 1.5418 Å), a step size of 0.02° (2θ), and a scan rate of 3° min−1. EPR spectra were collected on a Bruker EMX plus-6/1 spectrometer operating at X-band frequencies. UV–vis absorption spectra were obtained using a Shimadzu UV-3600 spectrophotometer over a wavelength range of 200–900 nm. Elemental composition analysis was performed by ICP using a Shimadzu ICPE-9800 system. TGA was carried out on a PerkinElmer STA6000 instrument under a nitrogen atmosphere with a heating rate of 10 °C min−1.

Preparation of sulfur and metal electrodes
The sulfur (Aladdin, 99.9 %) and A/C-CoNiS powders were mixed at a weight ratio of 7:3 for 10 min using an agate mortar. The mixture was transferred to a stainless-steel high-pressure reactor, sealed under an argon atmosphere in a glovebox, and heated at 155 °C for 12 h to allow sulfur diffusion into the A/C-CoNiS. The working electrodes were prepared by mixing the as-synthesized sulfur composite (active material), CNT (XFNANO, 99.5 %, conductive additive), and poly(acrylic acid) (PAA, Aladdin, 99 %, Mw 45,000, binder) at a weight ratio of 7:2:1 in deionized water (solvent). The solvent-to-solid weight ratio in the slurry was 5:1. The slurry was cast using a doctor blade onto a copper foil current collector (Canrd, 99.8 %, 9 μm in thickness), dried under vacuum at 40 °C overnight, and then cut into discs (12 mm in diameter) using a disc cutter (MTI). The final composite electrode had a sulfur content of 49 wt%, an active material loading of ~1.0 mg cm−2, and a thickness of ~64.4 μm. The C-CoNiS/S, MXene/S, and KB/S electrodes were fabricated following the same procedure. Sodium metal electrodes were prepared by rolling sodium metal (Aladdin, 99.7 %) into foils with a thickness of 0.2 mm and a diameter of 12 mm.

Electrochemical measurements
CR2032 coin cells (Canrd, 304 stainless steel) were assembled in an argon-filled glovebox at room temperature (H2O and O2 < 0.01 ppm). Each cell was filled with 180 μL of electrolyte (1.0 M NaSO3CF3 in diethyleneglycol dimethylether (DEGDME), Dodochem, 99.9 %), resulting in an E/S ratio of 180 μL mg−1. A glass fiber (Whatman GF/D, 14 mm diameter, thickness 0.67 mm) served as separator. Cells were sealed using a hydraulic press (~80 kg cm−2). All the cells were aged at room temperature for 4 h before testing. Cycling tests at −20 °C and 50 °C were carried out in an environmental chamber with negligible temperature variation (± 0.5 °C). Room-temperature cycling tests were performed under ambient laboratory conditions at an average temperature of 23 ± 2 °C.

The coin cells were activated for three cycles at specific currents of 0.5 Ag−1 within the voltage range of 0.2–2.8 V prior to the main measurements. Galvanostatic charge–discharge tests were conducted on a LAND system. EIS measurements were performed using a CHI 660E electrochemical workstation (Chenhua, Shanghai) in a potentiostatic mode with an AC amplitude of 5 mV over a frequency range of 100 kHz to 0.01 Hz (12 points per decade). For in situ EIS measurements, the cells were galvanostatically charged and discharged at a specific current of 300 mAg−1. EIS spectra were recorded at 0.2 V intervals, with each measurement preceded by a 30 min constant-voltage hold to reach a quasi-equilibrium state. The DRT results were subsequently acquired by transforming the EIS data from frequency to time domain through the MATLAB Graphical User Interface (GUI) toolbox. CV measurements were performed at a scan rate of 0.2 mV s−1 within 0.2–2.8 V vs Na+/Na. For all cycling performance figures, capacity retention and decay rates were calculated using the discharge capacities of the first cycle and the final cycles shown in each figure.

Polysulfide adsorption tests
2.5 mM Na2S6 solution was prepared by dissolving stoichiometric amounts of sulfur and anhydrous Na2S (Aladdin, 95 %) in 10 mL of DEGDME. The mixture was heated to 80 °C and stirred continuously for 48 h in an argon-filled glovebox. For adsorption experiments, 10 mg of powder (A/C-CoNiS or C-CoNiS) was added to 2 mL Na2S6 solution. After standing for 12 h, the color change of the solution was recorded with a digital camera, and the supernatant was analyzed by UV–vis spectroscopy (after 10-fold dilution). The powders were then dried and characterized by XPS to investigate chemical interactions between the catalysts and polysulfides. To quantify adsorption capacity, UV–vis spectra of Na2S6 solutions at varying concentrations (0.05, 0.10, 0.15, 0.20, and 0.25 mM) were measured.

Assembly and testing of symmetric cells
A/C-CoNiS and C-CoNiS powders were separately mixed with PAA at a weight ratio of 9:1 to form a slurry, which was then coated onto copper foil as electrode. Each cell used 40 μL of electrolyte containing Na2S6 at positive electrode, 40 μL of electrolyte without Na2S6 at negative electrode, and glass fiber membrane as the separator. CV curves were recorded at a scan rate of 5 mV s–1 within a voltage window of −1.0–1.0 V.

Theoretical calculations
All first-principles calculations were conducted using the Vienna Abinitio Simulation Package (VASP). The electron exchange-correlation energy was described using the Perdew–Burke–Ernzerhof (PBE) exchange-correlation functional within the generalized gradient approximation (GGA) framework. To accurately describe the strong electron correlation effects in transition metals, the DFT+U method was employed with Hubbard U parameters of 3.32 eV for Co, 6.20 eV for Ni, and 5.80 eV for Ti52,53. The empirical dispersions of Grimme (DFT-D3) were applied to account for the long-range van der Waals interactions49. To align with experimental characterizations, the (311) surface was cleaved from the (Co0.5Ni0.5)9S8 structure. For calculations involving NaSx (x = 8, 6, 4, 2, and 1), a 1×2×1 Monkhorst-Pack Gamma-centered k-point mesh was employed. The cutoff energy was set to 500 eV for all calculations, with convergence criteria of 0.01 eV Å−1 for forces and 10−5 eV for energy. The adsorption energy (Eads) was calculated using the following equation, Eads = Etotal − Esurf – Eadsorb where Etotal represents the total energy of the adsorbed system, Esurf is the energy of the optimized clean substrate, and Eadsorb denotes the energy of the adsorbate in vacuum. The optimized atomic coordinates are provided in Supplementary Data 1.

Peer review rounds
[{"round": 1, "reviewer_comments": {"reviewer_1": "This manuscript presents a novel catalyst designed for wide-temperature-range sodium-sulfur (Na-S) batteries, demonstrating high specific capacities. The unique amorphous/crystalline interwoven structure significantly enhances the kinetics of the sulfur electrode, particularly in facilitating the complex 16-electron transfer process. The development of wide temperature, especially low-temperature, Na-S batteries is a compelling advancement in the field. A minor revision is recommended, and the following points should be addressed:\nQ1. The charge/discharge process involves multi-step reactions. It is crucial for the authors to clearly elucidate the distinct electrochemical pathways influenced by the catalyst. Clarifying how the catalyst modulates these pathways would significantly enhance the understanding of its role in the reaction mechanism.\nQ2. Given the inherent thermal instability of sulfur, did the sulfur electrode exhibit any signs of fuming or degradation during the high-temperature tests? Addressing this concern would provide valuable insights into the practical stability and safety of the electrode under operational conditions.\nQ3. Please provide detailed coin cell assembly parameters, including but not limited to the compression pressure applied during electrode stacking, the aging time between cell assembly and electrochemical testing, and environmental controls such as temperature during assembly.\nQ4. Please add the details of the loading amount of active material of the electrode, the effective area of the current collector and the mass fraction of active components. These parameters are essential for accurately evaluating electrochemical performance.\nQ5. Although DFT calculations confirm MXene’s adsorption ability, experiment evidence is also needed. Please provide experiment results to strengthen the reliability of the computational findings.\nQ6. It looks like the samples correspond to wrong data in Figure 4c. As described in the manuscript, A/C-CoNiS exhibits lower Rct. Please carefully check the data and make necessary change.\nQ7. Several figure corrections are required to ensure clarity and consistency.\na. The sulfur loading unit in Figure 2c needs to be corrected from “mg cm−1” to “mg cm−2.”\nb. The y-axis units in Figure 3a need to be verified for accuracy.\nc. “ICP-OES” should be correctly spelled.\nd. It looks a little unclear for the word “crystal” in Figure 1a.\ne. It’s hard to find Sn atoms in Figure 5e.\nf. There should be no Sn atoms in Figure 5b.", "reviewer_2": "In this manuscript, CoNiS multipod-like structure with amorphous/crystalline interface were synthesized by the authors through Sn doping approach, which achieved superior performance when applied in Na–S batteries. However, this manuscript not only contains errors in writing and images but also lacks reasonable mechanism and functional explanations for A/C-CoNiS electrodes with ultra-high specific capacity. The authors alao did not clearly explain the reasons and characteristics for the excellent electrochemical performance of the material under high and low-temperature conditions. Moreover, the manuscript lacks in-situ characterization methods to support the authors’ viewpoint. This manuscript is not recommended for publication.\n1. The specific attribution and meaning of different platforms in the charge-discharge curve (Figure 2a) and different peaks in the CV curve (Figure 4a) have not been explained in detail by the authors.\n2. In Figure 4a, the authors mentioned that the oxidation-reduction peak at ~0.38 V corresponds to the reduction of the catalyst. Has a new catalyst been formed or not? Does the new catalytic phase play a catalytic role. In-situ electrochemical technology can reveal the dynamic changes of electrode materials during battery charging and discharging processes. In-situ electrochemical research is highly necessary. Please add in-situ electrochemical characterization.\n3. The authors mentioned in the manuscript that Sn doping interferes with crystal growth, forming crystalline and amorphous interfaces. What is the uniqueness of Sn? Will doping with other elements have the same effect? The authors should provide relevant experimental data.\n4. The sulfur loading on the electrode is an important parameter for battery performance. The authors should provide relevant data.\n5. The A/C-CoNiS electrode exhibits relative good electrochemical performance under different temperatures. Please explain in detail the unique advantages and characteristics of this material that can be used as an electrocatalyst for Na–S batteries at different temperatures.\n6. The charging and discharging voltage range of the battery in this manuscript is 0.2-2.8 V. Within this voltage range, whether the synthesized sulfide contribute to the capacity or not?\n7. In this manuscript, the battery has relative good electrochemical performance, but there are differences and contingencies in electrochemical testing. Please provide three parallel sets of test data and add error bars.\n8. The complete cyclic voltammetry curve (charge and discharge) in Figure 3a should be provided by the authors.\n9. There is a lack of research summary on amorphous crystalline structures in the field of metal–sulfur batteries. It is recommended to add the latest research results on related materials.\n10. There are many type/grammar errors and also images in this manuscript, for example, in line 275, red and green, and there is no green in the image. In Figure 4c, the A/C-CoNiS electrode has a higher electrochemical impedance, and there are errors in plotting and expression.", "reviewer_3": "The manuscript presents a compelling advancement in Na–S battery catalysts. Strengthening the link between Sn doping, structural modulation, and performance, along with contextualizing claims relative to existing literature, would elevate its impact. Addressing the following issues will ensure broader accessibility. Some comments need to be addressed before publication:\n1. Pore size and surface area not clearly stated in the text. Is the structure micro/meso/macroporous?\n2. A Whatman glass fiber separator is used instead of a typical Celgard polymer separator. The former is much thicker and will reduce energy density. What is the cycling performance using Celgard separator?\n3. There are many reports on sulfur host materials and it is currently known that anode and electrolyte are more of a problem in these battery systems than new cathode host materials. And it is always a bit suspicious if the one and only solution comes up with a new quite exotic composite material.\n4. It might be a good idea to quantify the adsorption capacity with UV Vis following the method reported by Hippauf. This would give a good comparison with other more polar carbon host materials as reported by Hao. Also a water isotherm would be helpful to check the hydrophilic character of the host.\n5. Of course a big flaw are the limited experimental details. No electrolyte/sulfur ratio given. That’s a step backwards in reporting accurate data. With a whatman separator (thick) an excess of electrolyte is guaranteed! The huge capacity loss in the first cycle confirms this view (dissolution). And in a flooded cell PS diffusion takes longer. And the glass fibres also adsorb the PS, and affect crystallization.\nIt would be good to test the material also with a PE separator and compare it to a Ketjen Black based reference cathode. And check performance also under lean conditions with E/S ratios varying between 5 and 10.\n6. Why is cobalt used rather than another metal; is the choice of cobalt important? I don’t think the choice of cobalt versus other transition metals is discussed in the paper and the computational authors could test other metal ions!", "reviewer_4": "This manuscript presents a comprehensive study aimed at mitigating the polysulfide shuttle effect in Na–S batteries through the design and application of a Sn-doped CoNiS catalyst. By integrating both experimental investigations and density functional theory (DFT) calculations, the authors have made commendable efforts to elucidate the role of the electrocatalyst in enhancing the electrochemical performance of Na–S batteries. While the study offers promising insights and contributes to the development of effective shuttle suppression strategies, several critical aspects require further clarification and elaboration. In particular, addressing certain mechanistic details and expanding the discussion of computational findings will significantly strengthen the depth and impact of the work. Specific comments and suggestions are provided below to help improve the overall quality and completeness of the manuscript\n1. In this study involving Na₂Sₓ species (x = 8, 6, 4, 2, and 1), the authors mention the use of a 1×1×1 Monkhorst-Pack Gamma-centered k-point mesh and a plane-wave energy cutoff of 400 eV for all calculations. Could the authors please clarify the rationale behind selecting the Gamma point for k-point sampling and the specific cutoff energy value? Additionally, did the authors perform any convergence tests with respect to the k-point mesh and energy cutoff to ensure the reliability and accuracy of the computed results?\n2. Considering the presence of transition metal atoms with localized d-electrons in your system, did the authors consider employing the DFT+U approach to better account for on-site Coulomb interactions? If not, could you please elaborate on the justification for omitting the Hubbard U correction, and whether any test calculations were conducted to assess its potential impact on the electronic structure and total energy?\n3. In the DFT investigation of the A/C-CoNiS interface and its role in catalytic reaction kinetics, how did the authors determine the specific active site(s) for Na–S adsorption, particularly considering the structural heterogeneity and potentially numerous adsorption sites present in the amorphous region? Given that amorphous structures can host a variety of chemically distinct sites, was any systematic approach like energy screening was employed to identify the most representative or catalytically relevant sites?\n4. (a) The results indicate that the amorphous region of the A/C-CoNiS system exhibits the highest binding energies for Na–S adsorption compared to the crystalline counterpart. Could the authors provide further insights into the underlying factors responsible for these enhanced adsorption energies at the amorphous sites? A detailed discussion on the bonding nature—such as charge transfer characteristics, local coordination environments, or electronic structure analysis—would greatly aid in understanding the origin of the stronger interaction.\n(b) Was any assessment of the system’s electronic conductivity performed to evaluate its influence on the overall catalytic performance? Given that electronic transport plays a crucial role in redox kinetics, such analysis would be of significant value.\n(c) In addition, the manuscript briefly mentions Sn doping in the catalyst. Could the authors elaborate on the specific role of Sn in modifying the catalyst’s properties? In particular, does Sn incorporation induce any notable changes in the electronic structure or charge redistribution that could influence Na–S adsorption or reaction kinetics?\n5. The reversibility of the Na–S battery is a critical parameter influencing long-term performance. In this context, could the authors provide insights into the sodium diffusion mechanism during the charging process? Specifically, how does the Na–S bond cleavage proceed on the catalyst surface, and what are the associated kinetic barriers? It would be helpful if the authors could support their discussion with a kinetic analysis—such as nudged elastic band (NEB) calculations—to quantify the energy barriers involved in Na diffusion and bond dissociation. Was such an analysis performed or considered?\n6. MXene has been previously reported to strongly adsorb Na–S species, which may result in structural integrity challenges in Na–S battery systems. Given its role as a substrate in your catalyst design, did the authors consider or evaluate the potential charge transfer between the MXene and the active catalytic components? Such electronic interactions could significantly influence the adsorption strength, electronic structure, and catalytic activity. An analysis of charge redistribution (e.g., Bader charge analysis or density of states) would provide valuable insights into the impact of the MXene support on the overall catalytic behavior."}, "author_response": "Response Letter for Manuscript “Amorphous-crystalline interwoven multipods with high Co/Ni activity for sodium-sulfur battery operated from −20 to 50 °C”\nThank you for reading this letter. We are grateful to the editor for the opportunity to revise our manuscript and wish to extend our sincere thanks to the reviewers for their insightful comments. We have carefully considered all the feedback and revised the manuscript accordingly.\nThe revision includes five main updates. (1) Kinetic mechanism: in situ EIS and corresponding DRT analysis were added to investigate the kinetics of the polysulfide conversion process at 25 and −20 °C. (2) Adsorption validation: quantitative adsorption experiments were conducted at 25 and 50 °C to confirm the superior adsorption of A/C-CoNiS for polysulfides. (3) DFT calculations: systematic screening of the active sites and analysis of the charge redistribution induced by Sn doping were performed. Supplementary CI-NEB and differential charge density analyses further confirmed the enhanced reaction kinetics and polysulfide adsorption. (4) Battery configuration and reproducibility: detailed cell assembly parameters and three independent parallel tests for battery performance were provided. (5) Figures and clarity: writing and figure errors were corrected, and some figures as well as supplementary materials were reorganized to improve readability and accuracy.\nDuring the revision, the author list was updated to reflect contributions: Nian Ran was added as co-first author for DFT calculations and method improvements (data in this part were all re-calculated and improved); Yuxuan Gao was added for supporting in situ EIS measurements. Xingyu Li was removed due to insufficient contribution. All changes were agreed upon by the original and added authors, with informed consent obtained. A signed nr-author-list-change-form is attached. We appreciate your understanding, and please do not hesitate to contact us if any additional information or materials are required.\nGeneral Comments: This manuscript presents a novel catalyst designed for wide-temperature-range sodium-sulfur (Na-S) batteries, demonstrating high specific capacities. The unique amorphous/crystalline interwoven structure significantly enhances the kinetics of the sulfur electrode, particularly in facilitating the complex 16-electron transfer process. The development of wide temperature, especially low-temperature, Na-S batteries is a compelling advancement in the field. A minor revision is recommended, and the following points should be addressed:\nResponse: Thank you very much for your valuable comments and suggestions, which are helpful to greatly improve the quality of our manuscript. We respond to your comments one by one as follows. Thanks again.\nComment 1-1: The charge/discharge process involves multi-step reactions. It is crucial for the authors to clearly elucidate the distinct electrochemical pathways influenced by the catalyst. Clarifying how the catalyst modulates these pathways would significantly enhance the understanding of its role in the reaction mechanism.\nResponse 1-1: We sincerely thank the reviewer for the insightful comment. We separately discuss the roles of the catalyst in the discharge process steps of (1) Na S (6<x≤8) → Na S , (2) Na S → Na S, as well as (3) in the charge process.\n2 x 2 4 2 4 2\n(1) Discharge process: Na S (6<x≤8) → Na S\n2 x 2 4\nLong-chain soluble polysulfides induce severe shuttle effects. Quantitative UV–vis analysis reveals that A/C-CoNiS has a significantly higher Na S adsorption capacity than C-CoNiS, particularly at 50 °C (Supplementary Table 3, Fig. 4h and Supplementary Fig.21 and 22). As a result, the shuttle effect is suppressed, which is beneficial to the cycling performance of the battery.\n2 6\n2\n(2) Discharge process: Na S →Na S\n2 4 2\nIn situ EIS tests were conducted to investigate the reaction kinetics of the battery, especially during the rate-limiting step. In this process, the charge transfer resistance (R ) of A/C-CoNiS/S remains stable, whereas the R of C-CoNiS/S exhibits a significant increase.\nct ct\nThis indicates that A/C-CoNiS/S has an excellent catalytic effect on the rate-determining step (Supplementary Fig. 25). Under low-temperature conditions, the difference between the two sample is even more pronounced. The according Distribution of Relaxation Times (DRT) profiles in Fig. 4c-f further confirm this conclusion.\n(3) Charge process\nThe ion diffusion significantly slows down at low temperatures. As a result, in the DRT spectra of A/C-CoNiS/S and C-CoNiS/S at −20 °C in Fig. 4c-f, there is a pronounced peak during the charge process in the relaxation time around 10−2 s, which corresponds to the ion diffusion process (J. Am. Chem. Soc. 2025, 147, 8250). The significantly reduced signal indicates that A/C-CoNiS can significantly accelerate the ion diffusion. This enables the battery to maintain excellent rate performance even at low temperatures. Additionally, the smaller R also indicates A/C-CoNiS/S exhibits faster reaction kinetics during the charging process.\nct\nIn summary, during the three discharge/charge processes discussed above, the main roles of A/C-CoNiS are to suppress the shuttle effect of polysulfides, accelerate the reaction kinetics of the rate-determining step, and promote the ion diffusion, respectively. These features contribute to the superior electrochemical performance across a wide temperature range of A/C-CoNiS/S. We have further expanded the mechanistic discussion in the revised manuscript with detailed analyses of each conversion step.\nRelated Revision:\n(Manuscript, page 11–12, 28)\n8 2 6 2 6\nIn situ EIS tests and corresponding distribution of relaxation times (DRT) analyses were conducted at 25 and −20 °C to evaluate the electrochemical catalytic performance across the full working voltage range (Figs. 4c-f, Supplementary Fig. 23). The time constant (τ) represents\n4\nthe relaxation time of each electrochemical process. As shown in Figs. 4c-f, each contour plot can be divided into four regions corresponding to interphase contact resistance (R1), charge transfer resistance (R2, R ), polysulfide diffusion resistance (R3), and ion diffusion resistance (R4) 34. At 25 °C, the A/C-CoNiS/S electrode consistently exhibits lower R than C-CoNiS/S (Figs. 4c and 4d). This trend becomes more pronounced at −20 °C (Figs. 4e and 4f), indicating the excellent catalytic performance of A/C-CoNiS/S at low temperatures.\nct ct\n(Manuscript, page 14)\nMoreover, in situ EIS and corresponding DRT analysis verify that A/C-CoNiS effectively accelerates reaction kinetics particularly under low-temperature conditions.\n(Supplementary information, page 27)\nSupplementary Fig. 23 | In situ EIS of Na–S batteries with different cathodes under various temperatures. a A/C-CoNiS/S at 25 °C, b C-CoNiS/S at 25 °C, c A/C-CoNiS/S at –20 °C, and d C-CoNiS/S at –20 °C. e, f Full-range impedance spectra corresponding to the representative curves at 1.6 and 1.8 V during discharge process in c and d, respectively. In situ EIS was employed to monitor the reaction kinetics during discharge/charge process. The R of A/C-CoNiS/S remains consistently lower than that of C-CoNiS/S at 25 °C by observing semicircle diameter. The difference between the two samples becomes more pronounced at\nct\n5\n−20 °C. Furthermore, the maximum value of R for both A/C-CoNiS/S and C-CoNiS/S can be detected at ~1.8 V at 25 °C. However, at −20 °C, the peak R of A/C-CoNiS/S remains at 1.8 V with a slight increase, while that of C-CoNiS/S shifts to 1.6 V and rises sharply, suggesting enhanced polarization and slower kinetics 34,35. The results indicate A/C-CoNiS/S maintains stable charge transfer kinetics even at low temperature, demonstrating a superior low-temperature adaptability 35.\nct ct\n(Manuscript, page 12)\nFig. 4h shows that A/C-CoNiS exhibits a markedly weaker UV-vis absorption signal than C-CoNiS and the Na S solution at room temperature, revealing superior adsorption ability.\n2 6\nQuantitative UV-vis adsorption tests (Supplementary Figs. 24 and 25, Table 4) confirm that A/C-CoNiS exhibits superior adsorption capacities especially at high temperatures, indicating an improved anti-shuttle effect.\n(Supplementary information, page 28–30)\nSupplementary Fig. 24 | A linear calibration curve was established based on Na S solutions of known concentrations. a UV–vis absorption spectra of Na S solutions with varying concentrations. b Corresponding calibration curve used for quantitative analysis.\n2 6 2 6\nBased on the established calibration curve, the adsorption capacity of the catalyst for polysulfides can be quantitatively determined from the corresponding UV–vis absorption data.\n2 6 2 6\nSupplementary Table 4.\nPolysulfide adsorption capacity of A/C-CoNiS and C-CoNiS at different temperatures.\nTemperature Adsorption Capacity Adsorption Capacity\nSample\n(ºC) (mmol·g−1) (g ·g−1)\ns\n25 0.336 0.080\nA/C-CoNiS\n50 0.328 0.078\n25 0.235 0.056\nC-CoNiS\n50 0.086 0.020\n(Manuscript, page 18)\nPolysulfide adsorption tests\n2.5 mM Na S solution was prepared by dissolving stoichiometric amounts of sulfur and anhydrous sodium sulfide (Na S, AR) in 10 mL of DEGDME. The mixture was heated to 80 °C and stirred continuously for 48h in an argon-filled glove box. For adsorption experiments, 10 mg of powder (A/C-CoNiS or C-CoNiS) was added to 2 mL Na S solution. After standing\n2 6 2 2 6\n7\nfor 12h, the color change of the solution was recorded with a digital camera, and the supernatant was analyzed by UV-vis spectroscopy (after 10-fold dilution). The powders were then dried and characterized by XPS to investigate chemical interactions between the catalysts and polysulfides. To quantify adsorption capacity, UV-vis spectra of Na S solutions at varying concentrations (0.05, 0.10, 0.15, 0.20, and 0.25 mM) were measured.\n2 6\nComment 1-2: Given the inherent thermal instability of sulfur, did the sulfur electrode exhibit any signs of fuming or degradation during the high-temperature tests? Addressing this concern would provide valuable insights into the practical stability and safety of the electrode under operational conditions.\nResponse 1-2: We appreciate the reviewer’s comment. TGA results (Supplementary Fig. 11) show noticeable mass loss only above 55 °C. Since 50 °C is well below the boiling point of elemental sulfur (~115 °C) (Natl. Sci. Rev. 2023, 10, 268), significant evaporation is unlikely at this temperature. Moreover, long-term cycling at 50 °C shows a capacity decay of only 0.002% per cycle (Fig. 3e), further confirming that sulfur loss is negligible. In summary, these results demonstrate that the sulfur electrode exhibits excellent thermal stability and good safety at 50 °C.\nRelated Revision:\n(Supplementary information, page 13)\nComment 1-3: Please provide detailed coin cell assembly parameters, including but not limited to the compression pressure applied during electrode stacking, the aging time between cell assembly and electrochemical testing, and environmental controls such as temperature during assembly.\nResponse 1-3: We thank the reviewer for the insightful suggestion. As shown below, detailed assembly parameters have been included in the revised Methods section of the manuscript.\nRelated Revision:\n(Manuscript, page 17)\nElectrochemical measurements\nCR2032 coin cells were assembled in an argon-filled glovebox at room temperature (H O and O < 0.01 ppm). Each cell was filled with 180 μL of 1.0 M NaSO CF in DEGDME. A Whatman glass fiber membrane and a sodium foil (1 mm thick, 14 mm diameter) served as separator and counter electrode, respectively. Cells were sealed using a hydraulic press (~80 kg cm−2). All the cells were aged at room temperature for 4h before testing. Galvanostatic charge–discharge tests were conducted between 0.2–2.8 V on a LAND system. CV was conducted at the same voltage range, and EIS was performed at open-circuit potential across a frequency range of 0.01~100 kHz using a CHI600E electrochemical workstation. In situ EIS was carried out in the same frequency range during galvanostatic charge–discharge cycling with an interval of 30 min. The DRT results were subsequently acquired by transforming the\n2 2 3 3\nComment 1-4: Please add the details of the loading amount of active material of the electrode, the effective area of the current collector and the mass fraction of active components. These parameters are essential for accurately evaluating electrochemical performance.\nResponse 1-4: Thank you for this valuable suggestion. According to the reviewers’ comments, we have added relevant information in the revised manuscript.\nRelated Revision:\n(Manuscript, page 16)\nPreparation of sulfur cathodes\nThe sulfur and A/C-CoNiS powders were mixed with a mass ratio of 7:3 for 10 min in an agate mortar. The mixture was transferred to a stainless-steel high-pressure reactor, sealed under argon in a glove box, and heated at 155 °C for 12h to allow sulfur diffusion into the A/C-CoNiS. The working electrodes were prepared by mixing active material, carbon black, and PAA binder (7:2:1 by weight) in deionized water, casting the obtained slurry onto copper foil, and drying under vacuum at 40 °C overnight. The active material loading was ~1.0 mg cm−2 with an electrode area of 1.13 cm2. The C-CoNiS/S, MXene/S, and KB/S cathodes were fabricated by the same way.\nComment 1-5: Although DFT calculations confirm MXene’s adsorption ability, experiment evidence is also needed. Please provide experiment results to strengthen the reliability of the computational findings.\nResponse 1-5: We thank the reviewer for this valuable suggestion. To experimentally validate the adsorption capability of MXene, we conducted UV–vis adsorption measurements. As\n10\nshown in Fig. R1, the characteristic peak of Na S was significantly weakened after adsorption.\n2 6\nIn addition, the adsorption capacity of MXene toward Na S was quantitatively calculated to be 0.41 mmol g−1 based on the results displayed in the Supplementary Fig. 24, which further confirms its strong affinity toward polysulfides and thus supports the computational findings.\n2 6\nFig. R1 UV–vis spectra of Na S solutions after immersion with MXene at 25 °C for 12 h.\n2 6\nComment 1-6: It looks like the samples correspond to wrong data in Figure 4c. As described in the manuscript, A/C-CoNiS exhibits lower Rct. Please carefully check the data and make necessary change.\nResponse 1-6: We appreciate the reviewer’s careful observation. We apologize for the oversight and correct this mistake in the revised manuscript.\nRelated Revision:\n(Supplementary information, page 31)\nct ct\nComment 1-7: Several figure corrections are required to ensure clarity and consistency.\na. The sulfur loading unit in Figure 2c needs to be corrected from “mg cm−1” to “mg cm−2.”\nb. The y-axis units in Figure 3a need to be verified for accuracy.\nc. “ICP-OES” should be correctly spelled.\nd. It looks a little unclear for the word “crystal” in Figure 1a.\ne. It’s hard to find Sn atoms in Figure 5e.\nf. There should be no Sn atoms in Figure 5b.\nResponse 1-7: We thank the reviewer for the helpful suggestions. The necessary corrections have been made, and the related figures have been carefully checked and revised accordingly to ensure consistency and clarity. Due to the large number of changes, we do not list each one here, but all revisions have been highlighted in the revised manuscript and SI.\nGeneral Comments: In this manuscript, CoNiS multipod-like structure with amorphous/crystalline interface were synthesized by the authors through Sn doping approach, which achieved superior performance when applied in Na–S batteries. However, this manuscript not only contains errors in writing and images but also lacks reasonable mechanism and functional explanations for A/C-CoNiS electrodes with ultra-high specific capacity. The authors alao did not clearly explain the reasons and characteristics for the excellent electrochemical performance of the material under high and low-temperature conditions. Moreover, the manuscript lacks in-situ characterization methods to support the authors’ viewpoint. This manuscript is not recommended for publication.\nResponse: We sincerely appreciate your thorough and meticulous evaluation of our manuscript, as well as the insightful and constructive comments provided. Based on your comments, we have made the corresponding revisions. We have carefully revised the entire manuscript to ensure that both the text and figures are free of errors. Building on the existing results and supplementary testing (in-situ EIS measurements, quantitative adsorption tests, etc.), together with support from the literature, we have conducted an in-depth investigation. These efforts have enabled us to systematically elucidate the origin of the high specific capacity of A/C-CoNiS/S, uncover the regulatory role of A/C-CoNiS in the reaction process, and clarify the mechanisms underlying its outstanding electrochemical performance across a wide temperature range. We response to your comments one by one as following. Thanks again.\nComment 2-1: The specific attribution and meaning of different platforms in the charge-discharge curve (Figure 2a) and different peaks in the CV curve (Figure 4a) have not been explained in detail by the authors.\nRelated Revision:\n(Manuscript, page 6)\nFig. 2a shows the galvanostatic charge-discharge (GCD) profiles of A/C-CoNiS/S and C-CoNiS/S electrodes. The discharge curve of A/C-CoNiS/S exhibits three voltage plateaus at ~2.0, 1.5, and 0.8 V, corresponding to the conversion from S to long-chain polysulfides (Na S , 6<x≤8), then to Na S , and finally to Na S. Upon charging, two main plateaus appear at 1.7 and 2.2 V, corresponding to the stepwise oxidation of Na S to Na S and then to Na S 28.\n8 2 x 2 4 2 2 2 4 2 x\n(Manuscript, page 10–11)\nThe CV curves in Fig. 4a display a series of well-defined reduction and oxidation peaks. Four distinct reduction peaks are observed at 1.97 (R ), 1.53 (R ), 1.17 (R ), and 0.81 V (R ), corresponding to the stepwise conversion of S to Na S (R ), Na S to Na S (R ), and Na S to Na S (R , R ) 16,36. In addition, two peaks at 0.94 V (R ) and 0.50 V (R ) are ascribed to Na+ insertion into CoNiS 46. The oxidation peaks at 1.30 (O , ), 1.54 (O ), 1.72 (O ), and 2.15 V (O ) correspond to the reverse process accordingly 34.\n0 1 2 3 8 2 x 0 2 x 2 4 1 2 4 2 3 M1 M2 1 M1 2 3, M2 4\nThe evolution of the CV curves during the initial cycles is shown in Supplementary Fig. 21.\nComment 2-2: In Figure 4a, the authors mentioned that the oxidation-reduction peak at ~0.38 V corresponds to the reduction of the catalyst. Has a new catalyst been formed or not? Does the new catalytic phase play a catalytic role. In-situ electrochemical technology can reveal the dynamic changes of electrode materials during battery charging and discharging processes.\nResponse 2-2: We appreciate the reviewer’s insightful question. Based on the CV and XRD results shown below, we confirm that no new catalyst was formed at this potential. We performed CV analysis of a Na-ion battery (A/C-CoNiS as the anode) and a Na–S battery (A/C-CoNiS/S). The results show that the Na-ion battery exhibits no reduction peak near 0.38 V (Fig. R2a), whereas the A/C-CoNiS/S battery displays a ~0.38 V reduction peak during the first three CV cycles, with gradually decreasing intensity until it disappears in the fourth cycle (Supplementary Fig. 23). The peak is most likely attributable to the formation of the SEI layer in the early cycles (ACS Nano 2023, 17, 19063-19075; Adv Mater 2020, 32, e1906700), rather than to catalyst reduction or the emergence of a new phase. Furthermore, the XRD pattern of A/C-CoNiS/S at 0.2 V (Fig. R2b) reveals no phase transformation. Taken together, the results indicate that no new catalytic phase is generated during cycling. The relevant content has been revised in manuscript and SI.\nWe also fully agree with the suggestion on the necessity of in-situ electrochemical characterization. Accordingly, we have performed in-situ EIS measurements to probe the dynamic behavior of the electrode during cycling at both 25 °C and −20 °C. Please check the corresponding revisions in the manuscript and SI.\nFig. R2 | a CV curve of the Na-ion battery using A/C-CoNiS as the anode. b XRD pattern of the A/C-CoNiS/S electrode discharged to 0.2 V.\n(Supplementary information, page 25)\nSupplementary Fig. 21 | CV curves of A/C-CoNiS/S at 0.2 mV s−1. During the initial cathodic scan, the reduction peaks at 2.15, 1.23, and 0.81 V correspond to the conversion of S to long-chain polysulfides (Na S , 6<x≤8), the transformation of Na S to short-chain Na S , and the final reduction of Na S to Na S, respectively 9,28-30. In addition, the reduction peak at approximately 0.23 V is most likely attributable to the formation of the SEI layer 31,32. The oxidation peaks are associated with the stepwise oxidation of Na S to Na S 23. In the CV curves of the later cycles, the reduction peaks related to sulfur species exhibit a noticeable shift and tend to stabilize, while the reduction peaks associated with the SEI gradually weaken and disappear by the fourth cycle 31,32. Furthermore, the oxidation peaks split from a single peak into multiple peaks and eventually stabilize. The splitting of the oxidation peaks may be due to more thorough oxidation of Na S 33. To investigate the properties of the battery during stable cycling, the CV data were collected from the fourth cycle unless otherwise specified.\n8 2 x 2 x 2 4 2 4 2 2 2 x 2\n(Manuscript, page 11–12, 28)\n8 2 6 2 6\nIn situ EIS tests and corresponding distribution of relaxation times (DRT) analyses were conducted at 25 and −20 °C to evaluate the electrochemical catalytic performance across the full working voltage range (Figs. 4c-f, Supplementary Fig. 23). The time constant (τ) represents\n17\nthe relaxation time of each electrochemical process. As shown in Figs. 4c-f, each contour plot can be divided into four regions corresponding to interphase contact resistance (R1), charge transfer resistance (R2, R ), polysulfide diffusion resistance (R3), and ion diffusion resistance (R4) 34. At 25 °C, the A/C-CoNiS/S electrode consistently exhibits lower R than C-CoNiS/S (Figs. 4c and 4d). This trend becomes more pronounced at −20 °C (Figs. 4e and 4f), indicating the excellent catalytic performance of A/C-CoNiS/S at low temperatures.\nct ct\n(Manuscript, page 14)\nMoreover, in situ EIS and corresponding DRT analysis verify that A/C-CoNiS effectively accelerates reaction kinetics particularly under low-temperature conditions.\n(Supplementary information, page 27)\nSupplementary Fig. 23 | In situ EIS of Na–S batteries with different cathodes under various temperatures. a A/C-CoNiS/S at 25 °C, b C-CoNiS/S at 25 °C, c A/C-CoNiS/S at –20 °C, and d C-CoNiS/S at –20 °C. e, f Full-range impedance spectra corresponding to the representative curves at 1.6 and 1.8 V during discharge process in c and d, respectively. In situ EIS was employed to monitor the reaction kinetics during discharge/charge process. The R of A/C-CoNiS/S remains consistently lower than that of C-CoNiS/S at 25 °C by observing semicircle diameter. The difference between the two samples becomes more pronounced at\nct\n18\n−20 °C. Furthermore, the maximum value of R for both A/C-CoNiS/S and C-CoNiS/S can be detected at ~1.8 V at 25 °C. However, at −20 °C, the peak R of A/C-CoNiS/S remains at 1.8 V with a slight increase, while that of C-CoNiS/S shifts to 1.6 V and rises sharply, suggesting enhanced polarization and slower kinetics 34,35. The results indicate A/C-CoNiS/S maintains stable charge transfer kinetics even at low temperature, demonstrating a superior low-temperature adaptability 35.\nct ct\nComment 2-3: The authors mentioned in the manuscript that Sn doping interferes with crystal growth, forming crystalline and amorphous interfaces. What is the uniqueness of Sn? Will doping with other elements have the same effect? The authors should provide relevant experimental data.\nResponse 2-3: We thank the reviewer for this valuable question. To elucidate the uniqueness of Sn doping, we synthesized a series of control samples with Mn, Cu, and Zn doping under identical conditions (Supplementary Figs. 5–7). The results reveal that only Sn doping enables the formation of well-defined crystalline–amorphous interfaces. Specifically, Mn shows negligible structural impact due to its ultralow doping level; Cu induces global polycrystallization with indistinct amorphous regions; and Zn leads to defect-rich polycrystalline nanoparticles where amorphous regions are hard to distinguish. In contrast, Sn uniquely enables partial disruption of crystal growth while preserving the single-crystalline backbone, resulting in localized amorphous regions and well-defined interfaces (Fig. 1d, Supplementary Fig. 4). This comparative analysis highlights that the atomic-scale interface engineering observed in Sn-doped samples cannot be replicated by other dopants, confirming the critical role of Sn in modulating phase structure and catalytic functionality. According to the reviewers’ comments, we have added a discussion of other metal doping in the revised manuscript and SI.\n(Manuscript, page 6)\nAdditionally, three other transition metals (Cu, Mn, and Zn) were selected for doping, but no comparable effects were observed (Supplementary Figs. 5-7).\n(Supplementary Information, page 7−9)\nSupplementary Fig. 5 | Characterizations on Cu-CoNiS. a XRD pattern. b HAADF-STEM image. c, d HRTEM image. e HAADF-STEM image with elemental mapping. f EDS spectrum.\nTo explore the effects of metal doping, a Cu-doped CoNiS sample (Cu-CoNiS) was synthesized. XRD pattern confirms the main phase of (CoNi) S . Supplementary Fig. 5b shows that Cu doping induces a distinct bowl-like morphology. Multiple randomly oriented lattice fringes confirm its polycrystalline structure (Supplementary Fig. 5c). The HRTEM image shows lattice fringes with a spacing of 0.28 nm, which can be indexed to the (311) planes of (CoNi) S . Elemental mapping and EDS analysis reveal uniform distribution of Co, Ni, and Cu with a molar ratio of 1: 0.8: 0.3. Unlike Sn doping, Cu can be readily incorporated, which significantly alters the nanostructure. Since the nanobowls are polycrystalline, it is\n9 8 9 8\n20\ndifficult to clearly distinguish between crystalline and amorphous regions, unlike in single-crystalline structures where the interface can be easily identified.\nSupplementary Fig. 6 | Characterizations on Mn-CoNiS. a XRD pattern. b HAADF-STEM image. c, d HRTEM image. e Elemental mapping. f EDS spectrum. To investigate the effect of metal doping, a Mn-doped CoNiS sample (Mn-CoNiS) was synthesized. XRD analysis (Supplementary Fig. 6a) confirms that the main phase remains (CoNi) S . The sample exhibits a bowl-like morphology, as shown in Supplementary Fig. 6b. Multiple randomly oriented lattice fringes confirm its polycrystalline structure (Supplementary Fig. 6c). HRTEM imaging (Supplementary Fig. 6d) reveals lattice fringes with a spacing of 0.28 nm, corresponding to the (311) plane of (CoNi) S . Elemental mapping (Supplementary Fig. 6e) and EDS analysis (Supplementary Fig. 6f) reveal a uniform distribution of Co, Ni, and Mn with a molar ratio of 1: 1: 0.01. These results suggest that Mn was not effectively incorporated into the CoNiS lattice. The bowl is also polycrystalline, which is hard to distinguish the crystal and amorphous regions.\n9 8 9 8\nTo explore the effects of metal doping, a Zn-doped CoNiS sample (Zn-CoNiS) was synthesized. XRD pattern confirms the main phase of (CoNi) S . Zn doping induces the formation of ~10 nm nanoparticles on the MXene surface (Supplementary Fig. 7b). The HRTEM image shows lattice fringes with a spacing of 0.18 nm, which can be indexed to the (440) planes of (CoNi) S . Elemental mapping and EDS analysis reveal uniform distribution of Co, Ni, and Zn with a molar ratio of 1: 0.9: 0.1. Unlike Sn doping, Zn doping results in nanoparticles with abundant defects. The ultrasmall size makes it difficult to distinguish the amorphous–crystalline interface, in sharp contrast to the clearly discernible amorphous region in the Sn-doped counterpart.\n9 8 9 8\nResponse 2-4: We thank the reviewer for highlighting this important aspect. The sulfur loading in all sodium–sulfur battery tests was controlled at ~1.0 mg cm−2. This information has been added in the “Electrochemical measurements” section of the revised manuscript.\nRelated Revision:\n(Manuscript, page 17)\nThe active material loading was ~1.0 mg cm−2 with an electrode area of 1.13 cm2. The C-CoNiS/S, MXene/S, and KB/S cathodes were fabricated by the same way.\nComment 2-5: The A/C-CoNiS electrode exhibits relative good electrochemical performance under different temperatures. Please explain in detail the unique advantages and characteristics of this material that can be used as an electrocatalyst for Na–S batteries at different temperatures.\nResponse 2-5: We sincerely appreciate the reviewer’s valuable comments. At high temperature of 50 °C, A/C-CoNiS effectively suppresses the shuttle effect of polysulfides, thereby enhancing the cycling stability of the battery. At low temperature of −20 °C, A/C-CoNiS effectively catalyzes the transformation of polysulfides, promoting the reaction kinetics of the battery. As a result, the obtained Na–S batteries exhibit excellent electrochemical performance across a wide temperature range. Detailed discussions are provided below.\nAt 50 °C, intensified polysulfide diffusion and shuttle effects typically degrade performance. UV–vis absorption quantification demonstrates that A/C-CoNiS maintains stronger and more stable polysulfide adsorption at both room temperature and 50 °C, effectively mitigating polysulfide migration and thereby enhancing cycling stability (Supplementary Table 3). The significantly improved cycling stability of A/C-CoNiS/S at 50 °C in Fig. 3e further confirms this conclusion.\nThis discussion has been incorporated into the revised manuscript and SI to emphasize the unique advantages of A/C-CoNiS in Na–S batteries at different temperatures.\nct\nRelated Revision:\n(Manuscript, page 12)\nFig. 4h shows that A/C-CoNiS exhibits a markedly weaker UV-vis absorption signal than C-CoNiS and the Na S solution at room temperature, revealing superior adsorption ability.\n2 6\nQuantitative UV-vis adsorption tests (Supplementary Figs. 24 and 25, Table 4) confirm that A/C-CoNiS exhibits superior adsorption capacities especially at high temperatures, indicating an improved anti-shuttle effect.\n(Supplementary information, page 28–30)\n2 6 2 6\nBased on the established calibration curve, the adsorption capacity of the catalyst for polysulfides can be quantitatively determined from the corresponding UV–vis absorption data.\nSupplementary Fig. 25 | UV-vis spectra of Na S solutions after immersion with A/C-CoNiS and C-CoNiS at 50 °C for 12 h. Insets: digital photographs of the solutions before and after adsorption. Compared to C-CoNiS and the Na S solution, A/C-CoNiS exhibits weaker UV-vis signals and a more transparent solution (inset), indicating stronger NaPSs adsorption and improved anti-shuttle capability 4.\n2 6 2 6\nSupplementary Table 4.\nPolysulfide adsorption capacity of A/C-CoNiS and C-CoNiS at different temperatures.\nTemperature Adsorption Capacity Adsorption Capacity\nSample\n(ºC) (mmol·g−1) (g ·g−1)\ns\n25 0.336 0.080\nA/C-CoNiS\n50 0.328 0.078\n25 0.235 0.056\nC-CoNiS\n50 0.086 0.020\n(Manuscript, page 18)\n2.5 mM Na S solution was prepared by dissolving stoichiometric amounts of sulfur and anhydrous sodium sulfide (Na S, AR) in 10 mL of DEGDME. The mixture was heated to 80 °C and stirred continuously for 48h in an argon-filled glove box. For adsorption experiments, 10 mg of powder (A/C-CoNiS or C-CoNiS) was added to 2 mL Na S solution. After standing\n2 6 2 2 6\nfor 12h, the color change of the solution was recorded with a digital camera, and the supernatant was analyzed by UV-vis spectroscopy (after 10-fold dilution). The powders were then dried and characterized by XPS to investigate chemical interactions between the catalysts and polysulfides. To quantify adsorption capacity, UV-vis spectra of Na S solutions at varying concentrations (0.05, 0.10, 0.15, 0.20, and 0.25 mM) were measured.\n2 6\nComment 2-6: The charging and discharging voltage range of the battery in this manuscript is 0.2-2.8 V. Within this voltage range, whether the synthesized sulfide contribute to the capacity or not?\nResponse 2-6: We thank the reviewer for this insightful question. To evaluate the capacity contribution of the synthesized sulfide within the voltage range of 0.2–2.8 V, we conducted cycling tests at a current density of 1 A g−1 (Supplementary Fig. 12b). After 250 cycles, the electrode delivers a capacity of 215.8 mAh g−1. Considering its 30 wt% content in the A/C-CoNiS/S composite, A/C-CoNiS contributes only 6.4% of the total capacity, confirming that sulfur is the primary capacity source.\nRelated Revision:\n(Manuscript, page 7)\nSupplementary Fig. 12a shows that the sodium-ion storage performance of A/C-CoNiS contributes minimally to the overall capacity, indirectly indicating that the main contribution comes from the redox process of sulfur. The MXene/S and Ketjen Black/S cathodes deliver\n26\ncapacities far below A/C-CoNiS/S, highlighting the catalytic advantage of A/C-CoNiS (Supplementary Fig. 12b and 12c).\n(Supplementary information, page 16)\nSupplementary Fig. 12 | Cycling stability of the A/C-CoNiS, MXene/S, and KB/S at 1 A g−1. In sodium-ion batteries, A/C-CoNiS delivers 215.8 mAh g−1 after 250 cycles at 1 A g−1 (Supplementary Fig. 12a). Considering its 30 wt% content in the A/C-CoNiS/S composite, A/C-CoNiS contributes only 6.4% of the total capacity, confirming that sulfur is the primary capacity source. In Na−S batteries, MXene/S and KB/S electrodes deliver discharge capacities of 365.1 and 339.4 mAh g−1 respectively after 250 cycles at 1 A g−1 (Supplementary Figs. 12b, c), highlighting the superior catalytic performance of A/C–CoNiS.\nComment 2-7: In this manuscript, the battery has relative good electrochemical performance, but there are differences and contingencies in electrochemical testing. Please provide three parallel sets of test data and add error bars.\nFig. R3 | Na–S battery performance at room temperature. a cycling performance at 1 A g−1 using A/C-CoNiS/S and C-CoNiS/S. b Cycle stability at a high sulfur loading at 1 A g−1. c rate performance of the two samples at current densities ranging from 0.5 to 5 A g−1. d Long-term cycling stability of the A/C-CoNiS/S cathode at 3 A g−1 over 1200 cycles.\nIn Fig. R3a, A/C-CoNiS/S shows a high capacity of 1422.3 mAh g−1 after 250 cycles at 1 A g−1 and a nearly 100 % coulombic efficiency (grey line). By contrast, C-CoNiS/S only achieves a discharge capacity of 694.4 mAh g−1 with a capacity decay of 0.015 % per cycle. Even we increased the sulfur loading to 3 mg cm−2, A/C-CoNiS/S can still give a capacity of 517.4 mAh g−1 after 400 cycles at 1 A g−1 and a nearly 100 % coulombic efficiency in Fig. R3b, surpassing most reported work (306~373 mAh g−1). Furthermore, A/C-CoNiS/S in Fig. R3c delivers high specific capacities of 1493.7, 1435.0, 1389.2, 1318.4, and 1278.2 mAh g−1 at 0.5,\n28\n1, 2, 3, 4, and 5 A g−1, respectively. Even when the current density decreases to 0.5 A g−1, the capacity can still be up to 1474.9 mAh g−1, indicating excellent reversibility and cycling stability. Impressively, the A/C-CoNiS/S cathode in Fig. R3d delivers a high capacity of 1314.7 mAh g−1 at 3 A g−1 after 1200 cycles with capacity decay rate of 0.005 % per cycle and coulombic efficiency of 99.9%.\nFig. R4 | Na–S Battery Performance at low and high temperatures. a Rate performance of A/C-CoNiS/S from 0.2 to 5 A g−1 at −20 °C. b Cycling performance for A/C-CoNiS/S and C-CoNiS/S at −20 °C. c Cycling performance of A/C-CoNiS/S and C-CoNiS/S at 50 °C.\nFig. R4a shows the rate performance of A/C-CoNiS/S at −20 °C. The A/C-CoNiS/S electrode delivers high specific capacities of 1036.7, 1000.0, 945.4, 907.4, 879.0, and 843.3 mAh g−1 at current densities of 0.5, 1, 2, 3, 4, and 5 A g−1, respectively. When the current density restores to 0.5 A g−1, the discharge capacity can still be up to 1024.3 mAh g−1 with almost no capacity loss. For comparison, the capacity of C-CoNiS/S decreases dramatically at 2 A g−1, showing no future application in low-temperature batteries. A/C-CoNiS/S provides a high capacity of 957.4 mAh g−1 after 400 cycles at 2 A g−1 at −20 °C in Fig. R4b, and coulombic efficiency of nearly 100 %. By contrast, C-CoNiS/S delivers 521.6 mAh g−1 after 140 cycles at 1 A g−1. Fig. R4c shows A/C-CoNiS/S gives an initial specific capacity of 1424.0 mAh g−1 at 2 A g−1, which slightly decreases to 1402.6 mAh g−1 after 700 cycles with an average capacity decay rate of 0.002 % per cycle at 50 °C. For comparison, C-CoNiS/S gives an initial discharge capacity of 825.9 mAh g−1 with an 81.2 % retention rate after 120 cycles.\n(Manuscript, page 8, 10)\nThe sudden capacity loss of C-CoNiS/S might be caused by short circuit influenced by shuttle effect in the battery at high temperatures. The above battery data were obtained from three independent parallel tests to ensure reproducibility (Supplementary Fig. 20).\nImpressively, the A/C-CoNiS/S cathode in Fig. 2g delivers a high capacity of 1320.8 mAh g−1 at 3 A g−1 after 1200 cycles with capacity decay rate of 0.012 % per cycle and coulombic efficiency of 99.9%. The above battery data were obtained from three independent parallel tests to ensure reproducibility (Supplementary Fig. 15).\n(Supplementary information, page 17, 23)\nSupplementary Fig. 15 | Na–S battery performance at room temperature. a cycling performance at 1 A g−1 using A/C-CoNiS/S and C-CoNiS/S. b Cycle stability at a high sulfur loading at 1 A g−1. c rate performance of the two samples at current densities ranging from 0.5 to 5 A g−1. d Long-term cycling stability of the A/C-CoNiS/S cathode at 3 A g−1 over 1200 cycles. Data from three parallel cells are presented, confirming the reproducibility of the battery\n30\nperformance.\nSupplementary Fig. 20 | Na–S battery performance at low and high temperatures. a Rate performance of A/C-CoNiS/S from 0.2 to 5 A g−1 at −20 °C. b Cycling performance for A/C-CoNiS/S and C-CoNiS/S at −20 °C. c Cycling performance of A/C-CoNiS/S and C-CoNiS/S at 50 °C. Data from three parallel cells are presented, confirming the reproducibility of the battery performance.\nComment 2-8: The complete cyclic voltammetry curve (charge and discharge) in Figure 3a should be provided by the authors.\nResponse 2-8: We thank the reviewer for the valuable suggestion. As the full CV curves at 25 °C have been shown in Fig. 4a in the previous version, we here supplement the complete CV curves at –20 °C and provide detailed explanations accordingly. Please check our revisions in the manuscript and SI.\nRelated Revision:\n(Manuscript, page 8−9)\nFig. 3a shows the change of CV peaks between room temperature (25 °C) and low temperature (−20 °C). As for the selected oxidation peak of O (Na S→Na S ), it’s clear that decreased temperature only makes A/C-CoNiS/S slightly shift by 0.09 V while makes C-CoNiS/S shift more positively by 0.20 V, indicating A/C-CoNiS provides a much easier conversion process for NaPSs at low temperatures. The complete CV curves at 25 °C and −20 °C were shown in Fig. 4a and Supplementary Fig. 16, respectively.\n2 2 2 4\n31\n(Supplementary Information, page 19)\nSupplementary Fig. 16 | CV curves of A/C-CoNiS/S and C-CoNiS/S at 0.2 mV s−1 at –20 °C. Four prominent cathodic peaks are observed at 1.91 V (R ), 1.43 V (R ), 0.89 V (R ), and 0.48 V (R ), along with a distinct peak at 0.61 V (R ). These peaks are sequentially associated with the stepwise reduction of sulfur species: R corresponds to the initial conversion of S into long-chain polysulfides (Na S , 6<x≤8); R to the transition from long-chain Na S to Na S ; R and R to the further reduction of Na S to Na S. The peak R is attributed to Na+ insertion into CoNiS 22. During the anodic sweep, the peaks labeled O to O are assigned to the progressive reoxidation of Na S back to Na S . The peak O arises from the extraction of Na+.\n0 1 2 3 M 0 8 1 2 x 2 x 2 4 2 3 2 4 2 M 1 4 2 2 x M\nFurthermore, A/C-CoNiS/S exhibits a larger current response and smaller polarization, indicating its excellent performance at –20 °C.\nComment 2-9: There is a lack of research summary on amorphous crystalline structures in the field of metal–sulfur batteries. It is recommended to add the latest research results on related materials.\nResponse 2-9: We thank the reviewer for the suggestion. We have incorporated a summary of the latest research advances on crystalline-amorphous heterostructures in the field of metal–sulfur batteries, with a focus on their role in enhancing polysulfide adsorption and catalytic conversion kinetics. Specifically, we have discussed recent works on: Phosphide-based\n32\namorphous-crystalline systems (Ni P/CeO , P-CoS /CNT) (Energy Storage Mater. 2024, 70, 103551, Chem. Eng. J. 2024, 70, 150696), Oxide-based heterostructures (c-a-MoO ) (Nano Energy 2025, 133, 110508). These heterostructures enhance performance by synergistically optimizing intermediate adsorption and conversion: amorphous regions provide abundant defects and active sites, strengthening adsorption of soluble intermediates (e.g., NaPSs/LiPSs) and accelerating electron/ion transport; crystalline regions offer ordered lattices and conductive pathways while buffering volume changes to improve cycling stability; and interfaces enable charge redistribution and built-in fields that lower reaction barriers and enhance catalytic activity.\n2 x 2 3\nThese additions strengthen the context of our study and highlight the novelty of our approach in designing highly efficient electrocatalysts for metal–sulfur batteries. The revised introduction now better situates our work within the current state-of-the-art.\nRelated Revision:\n(Manuscript, page 3–4)\nInterface engineering can be one feasible strategy to further promote the catalytic and adsorption performances towards polysulfides 17,18. Among different kinds of interfaces, the amorphous/crystalline one could be an ideal structure for Na–S batteries. It combines the advantages of both phases, including the high conductivity and structural stability of crystalline regions as well as the abundant active sites and strong adsorption capacity of amorphous regions 17-21. For instance, Lee et al. constructed a nanoscale crystalline–amorphous MoO heterostructure, which facilitated continuous adsorption and conversion of lithium polysulfides, leading to high sulfur utilization and exceptional cycling stability 19. Moreover, Liu et al. demonstrated that a crystalline–amorphous Ni P/CeO heterostructure with strong interfacial electronic interaction could accelerate Li S deposition/decomposition kinetics and improve long-term cycle life 20.\n3\n2 x\n2\nResponse 2-10: We appreciate the careful review. All relevant errors have been addressed. In addition, we have thoroughly reviewed the entire manuscript and corrected similar issues to ensure overall consistency and accuracy. Due to the large number of changes, we do not list each one here, but all revisions have been highlighted in the revised manuscript and SI.\nGeneral Comments: The manuscript presents a compelling advancement in Na–S battery catalysts. Strengthening the link between Sn doping, structural modulation, and performance, along with contextualizing claims relative to existing literature, would elevate its impact. Addressing the following issues will ensure broader accessibility. Some comments need to be addressed before publication:\nResponse: Thank you very much for your valuable comments and suggestions, which greatly contributes to improving the quality of our manuscript. We have addressed your comments one by one as follows.\nComment 3-1: Pore size and surface area not clearly stated in the text. Is the structure micro/meso/macroporous?\nResponse 3-1: We appreciate the reviewer’s insightful question. Nitrogen adsorption–desorption (BET) tests were performed to evaluate the materials’ specific surface area and pore size distribution. The results show that A/C-CoNiS exhibits a higher specific surface area (35.3 m2 g−1) and a mesoporous structure with a dominant pore size of approximately 3.9 nm (Supplementary Fig. 9). This mesoporous architecture enhances electrolyte infiltration, accelerates ion transport, and provides abundant active sites, thereby contributing to the improved electrochemical performance. In response to the reviewer’s comments, we have incorporated this discussion into the revised manuscript and SI.\nRelated Revision:\n(Manuscript, page 6)\nIn addition, nitrogen adsorption–desorption analysis confirms that A/C-CoNiS possesses a larger surface area and a mesoporous structure (~3.9 nm), which facilitates electrolyte infiltration and ion diffusion (Supplementary Fig. 10).\n35\n(Supplementary information, page 12)\nSupplementary Fig. 10 | BET characterization of A/C-CoNiS and C-CoNiS. a N adsorption–desorption isotherms. b Pore size distribution calculated by the BJH model.\nComment 3-2: A Whatman glass fiber separator is used instead of a typical Celgard polymer separator. The former is much thicker and will reduce energy density. What is the cycling performance using Celgard separator?\nResponse 3-2: We appreciate the reviewer’s valuable suggestion. We performed cycling tests using a PE separator (Fig. R5). At a current density of 0.2 A g−1, A/C-CoNiS/S delivered a discharge capacity of 1085.0 mAh g−1 after 60 cycles, with an average decay rate of 0.29% per cycle. Additionally, the Coulombic efficiency of the battery is close to 100%. The results demonstrate that the battery can also operate stably using a typical Celgard polymer separator.\nComment 3-3: There are many reports on sulfur host materials and it is currently known that anode and electrolyte are more of a problem in these battery systems than new cathode host materials. And it is always a bit suspicious if the one and only solution comes up with a new quite exotic composite material.\nResponse 3-3: We thank the reviewer for the thoughtful comment. We acknowledge that the anode and electrolyte are crucial to the battery, but we are convinced that research on the cathode catalyst is also important. We believe that our catalyst-oriented cathode design provides a valuable and complementary approach that contributes to the overall performance enhancement of practical room-temperature Na–S batteries.\nThe cathode of the Na–S battery involves redox reactions with 16 electrons. The slow reaction kinetics limit the rate performance of Na–S batteries, especially under low-temperature operating conditions. Introducing an efficient catalyst at the cathode can effectively promote the transformation of sulfur species, thereby improving its rate performance. Additionally, Na–S batteries also suffer from a severe shuttle effect of polysulfides, which is aggravated at high temperatures. By introducing rationally designed materials at the cathode, the anchoring of polysulfides can optimize the cycling stability of the battery.\nComment 3-4: It might be a good idea to quantify the adsorption capacity with UV Vis following the method reported by Hippauf. This would give a good comparison with other more polar carbon host materials as reported by Hao. Also a water isotherm would be helpful to check the hydrophilic character of the host.\nResponse 3-4: We sincerely appreciate the reviewer’s constructive suggestion. To address this, we quantitatively evaluated the polysulfide adsorption capacity of the catalysts using UV–vis spectroscopy (Supplementary Fig. 21). As shown in Supplementary Table 3, the adsorption capacities at 25 °C and 50 °C are 0.080 and 0.078 g g−1 for A/C-CoNiS, and 0.056 and 0.020 g g−1 for C-CoNiS, respectively. A/C-CoNiS consistently exhibits superior polysulfide adsorption, with the advantage being most pronounced at 50 °C. These results underscore the excellent temperature-adaptive adsorption capability of A/C-CoNiS.\nWe thank the reviewer for the suggestion to evaluate the hydrophilicity of the material using a water adsorption isotherm. However, since our system employs an ether-based electrolyte rather than an aqueous medium, water adsorption cannot accurately reflect the actual electrode–electrolyte interactions. Therefore, we used DEGDME as the probe liquid for contact angle measurements. The results reveal that the droplet spreads rapidly and reaches a contact angle near zero (Fig. R6), indicating excellent wettability. Furthermore, BET analysis (Supplementary Fig. 9) confirms that A/C-CoNiS possesses a mesoporous structure with a\n38\ndominant pore size of approximately 3.9 nm. This mesostructure facilitates electrolyte infiltration, ion transport, and polysulfide confinement through capillary and interfacial effects.\nThe consistent conclusions from the contact angle measurements and BET analysis demonstrate the strong affinity between A/C-CoNiS and DEGDME.\nPlease check the corresponding revisions in the manuscript and SI.\nFig. R6 | Contact angle measurement between DEGDME and the A/C-CoNiS surface.\nRelated Revision:\n(Manuscript, page 12)\nFig. 4h shows that A/C-CoNiS exhibits a markedly weaker UV-vis absorption signal than C-CoNiS and the Na S solution at room temperature, revealing superior adsorption ability.\n2 6\nQuantitative UV-vis adsorption tests (Supplementary Figs. 24 and 25, Table 4) confirm that A/C-CoNiS exhibits superior adsorption capacities especially at high temperatures, indicating an improved anti-shuttle effect.\n(Supplementary information, page 28–30)\n2 6 2 6\nBased on the established calibration curve, the adsorption capacity of the catalyst for polysulfides can be quantitatively determined from the corresponding UV–vis absorption data.\nSupplementary Fig. 25 | UV-vis spectra of Na S solutions after immersion with A/C-CoNiS and C-CoNiS at 50 °C for 12 h. Insets: digital photographs of the solutions before and after adsorption. Compared to C-CoNiS and the Na S solution, A/C-CoNiS exhibits weaker UV-vis signals and a more transparent solution (inset), indicating stronger NaPSs adsorption and improved anti-shuttle capability 4.\n2 6 2 6\nSupplementary Table 4.\nPolysulfide adsorption capacity of A/C-CoNiS and C-CoNiS at different temperatures.\nSample\n(ºC) (mmol·g−1) (g ·g−1)\ns\n25 0.336 0.080\nA/C-CoNiS\n50 0.328 0.078\n25 0.235 0.056\nC-CoNiS\n50 0.086 0.020\n(Manuscript, page 18)\nPolysulfide adsorption tests\n2.5 mM Na S solution was prepared by dissolving stoichiometric amounts of sulfur and anhydrous sodium sulfide (Na S, AR) in 10 mL of DEGDME. The mixture was heated to 80 °C and stirred continuously for 48h in an argon-filled glove box. For adsorption experiments, 10 mg of powder (A/C-CoNiS or C-CoNiS) was added to 2 mL Na S solution. After standing\n2 6 2 2 6\nfor 12h, the color change of the solution was recorded with a digital camera, and the supernatant was analyzed by UV-vis spectroscopy (after 10-fold dilution). The powders were then dried and characterized by XPS to investigate chemical interactions between the catalysts and polysulfides. To quantify adsorption capacity, UV-vis spectra of Na S solutions at varying concentrations (0.05, 0.10, 0.15, 0.20, and 0.25 mM) were measured.\n2 6\nComment 3-5: Of course a big flaw are the limited experimental details. No electrolyte/sulfur ratio given. That’s a step backwards in reporting accurate data. With a whatman separator (thick) an excess of electrolyte is guaranteed! The huge capacity loss in the first cycle confirms this view (dissolution). And in a flooded cell PS diffusion takes longer. And the glass fibres also adsorb the PS, and affect crystallization.\nResponse 3-5: We sincerely thank the reviewers for their valuable feedback. In our experiments, the electrolyte-to-sulfur (E/S) ratio was 180 μL mg−1, and additional experimental details have been included in the revised manuscript to enhance the clarity and reproducibility of the study. To address the reviewer’s concerns, we conducted a series of control experiments:\na. Replacing the Whatman glass fiber separator with a PE separator (Fig. R5), A/C-CoNiS/S delivered a discharge capacity of 1085.0 mAh g−1 after 60 cycles at 0.2 A g−1, corresponding to an average decay rate of 0.29% per cycle.\nb. At 1 A g−1, KB/S maintained a discharge capacity of 339.4 mAh g−1 after 250 cycles, after which the capacity declined sharply (Supplementary Fig. 12c).\nc. At an E/S ratio of 10 μL mg−1 (Supplementary Fig. 13), A/C-CoNiS/S retained a discharge capacity of 1146.9 mAh g−1 after 50 cycles at 0.2 A g−1.\nAccording to the reviewers’ comments, we have added a discussion of relevant discussion in the revised manuscript and SI.\nRelated Revision:\n(Manuscript, page 7)\nSupplementary Fig. 12a shows that the sodium-ion storage performance of A/C-CoNiS contributes minimally to the overall capacity, indirectly indicating that the main contribution comes from the redox process of sulfur. The MXene/S and Ketjen Black/S cathodes deliver capacities far below A/C-CoNiS/S, highlighting the catalytic advantage of A/C-CoNiS (Supplementary Fig. 12b and 12c).\n(Supplementary information, page 14)\n(Manuscript, page 7)\nNotably, the A/C-CoNiS/S cathode maintains a discharge capacity of 1146.9 mAh g−1 after 50 cycles at 0.2 A g−1 with an E/S ratio of about 10 μL mg−1 (Supplementary Fig. 13).\n(Supplementary information, page 15)\nComment 3-6: Why is cobalt used rather than another metal; is the choice of cobalt important? I don’t think the choice of cobalt versus other transition metals is discussed in the paper and the computational authors could test other metal ions!\nResponse 3-6: Thank you very much for your valuable comments. Cobalt was chosen due to its unique electronic configuration and balanced d-orbital occupancy, which favorably regulate polysulfide adsorption and catalytic conversion during sulfur redox reactions. Previous density functional theory studies have shown that the occupation of e and t orbitals in metal clusters plays a key role in polysulfide interaction (Fig. R7). The e /t ratio effectively describes binding strength and catalytic activity. Electrons in e orbitals influence the σ * and σ * antibonding states related to S–S bond cleavage, where excessive occupancy may hinder bond breaking. t electrons affect the σ * state, determining adsorption strength; high t occupancy may lead to overly strong binding and hinder desorption. Among the tested metals (Fe, Co, Ni, Cu, Zn), cobalt shows a moderate e /t ratio of 0.312, between Fe (0.301) and Ni (0.328). This balance helps avoid both over-retention (as in Fe) and weak adsorption (as in Zn), ensuring efficient polysulfide conversion and contributing to the improved SRR kinetics and cycling stability observed. (Nat. Nanotechnol. 2024, 19, 792-799)\ng 2g g 2g g 1 3 2g 3 2g g 2g\nBased on the unique advantages of Co mentioned above, we choose Co here. According to the reviewers’ comments, we have added a discussion of relevant discussion in the revised manuscript.\nFig. R7 | Correlation between polysulfide concentration and molecular orbitals of catalysts. a, Schematic for the degeneracy of molecular orbitals between polysulfides and catalysts. b, Projected DOS plots for different orbitals for Fe, Co, Ni, Cu and Zn catalysts (top to bottom). The x axis values are the energy levels subtracting the Fermi levels for each catalyst.\n45\nc, Synchrotron-based L -edge NEXAFS plots for the different catalysts. d, Theoretical and experimental confirmation of the SRR kinetic trend with DOS-based and NEXAFS-based e /t ratios for the different catalysts. The error bars indicate ±2 nm wavelength differences used to calculate the Li S concentrations.\n3 g 2g 2 4\nFig. R8 | a, LSV curves for the different catalysts. J is the current density based on the geo geometric area of electrode. b, Relationship between J and Li S concentration. The error bars indicate the ±2 nm wavelength difference used to calculate the polysulfide concentration. The dotted line is the linear fitting for the data points, and R2 is the coefficient of determination for linear fitting.\nd 2 4\nRelated Revision:\n(Manuscript, page 3)\nTransition metal sulfides have been proven to be efficient catalysts for metal-sulfur batteries 12, which might also be favorable for low-temperature batteries. Cobalt’s unique electronic structure enables a balance between polysulfide adsorption and conversion, ensuring stable catalytic performance across wide temperatures 13-15.\nGeneral Comments: This manuscript presents a comprehensive study aimed at mitigating the polysulfide shuttle effect in Na–S batteries through the design and application of a Sn-doped CoNiS catalyst. By integrating both experimental investigations and density functional theory (DFT) calculations, the authors have made commendable efforts to elucidate the role of the electrocatalyst in enhancing the electrochemical performance of Na–S batteries. While the study offers promising insights and contributes to the development of effective shuttle suppression strategies, several critical aspects require further clarification and elaboration. In particular, addressing certain mechanistic details and expanding the discussion of computational findings will significantly strengthen the depth and impact of the work. Specific comments and suggestions are provided below to help improve the overall quality and completeness of the manuscript.\nResponse: Thank you very much for your valuable comments and suggestions, which have greatly contributed to improving the quality of our manuscript. We have addressed your comments one by one as follows.\nComment 4-1: In this study involving Na₂Sₓ species (x = 8, 6, 4, 2, and 1), the authors mention the use of a 1×1×1 Monkhorst-Pack Gamma-centered k-point mesh and a plane-wave energy cutoff of 400 eV for all calculations. Could the authors please clarify the rationale behind selecting the Gamma point for k-point sampling and the specific cutoff energy value? Additionally, did the authors perform any convergence tests with respect to the k-point mesh and energy cutoff to ensure the reliability and accuracy of the computed results?\nResponse 4-1: We sincerely appreciate the reviewer’s valuable suggestion. In the initial calculations, such a setup is commonly employed for large supercells and surface slab systems, as it provides a reasonable balance between computational cost and accuracy. To further ensure\n47\nthe reliability of our results, we have conducted additional convergence tests by increasing the k-point mesh to 1×2×1 and the plane-wave cutoff energy to 500 eV. According to the reviewers’ comments, the relevant data and corresponding discussion have been incorporated into the revised manuscript and SI.\nRelated Revision:\n(Manuscript, page 18)\nTheoretical calculations\nAll first-principles calculations were conducted using the Vienna Ab initio Simulation Package (VASP). The electron exchange-correlation energy was described using the Perdew–Burke–Ernzerhof (PBE) exchange-correlation functional within the generalized gradient approximation (GGA) framework. To accurately describe the strong electron correlation effects in transition metals, the DFT+U method was employed with Hubbard U parameters of 3.32 eV for Co, 6.20 eV for Ni, and 5.80 eV for Ti 52,53. The empirical dispersions of Grimme (DFT-D3) were applied to account for the long-range van der Waals interactions 49. To align with experimental characterizations, the (311) surface was cleaved from the (Co Ni ) S structure. For calculations involving Na S (x = 8, 6, 4, 2, and 1), a 1×2×1 Monkhorst-Pack Gamma-centered k-point mesh was employed. The cutoff energy was set to 500 eV for all calculations, with convergence criteria of 0.01 eVÅ−1 for forces and 10−5 eV for energy. The adsorption energy (E ) was calculated using the following equation, E = E − E − E , where E represents the total energy of the adsorbed system, E is the energy of the optimized clean substrate, and E denotes the energy of the adsorbate in vacuum.\n0.5 0.5 9 8 2 x\nads ads adsorb/surf surf adsorb adsorb/surf surf adsorb\nComment 4-2: Considering the presence of transition metal atoms with localized d-electrons in your system, did the authors consider employing the DFT+U approach to better account for on-site Coulomb interactions? If not, could you please elaborate on the justification for\n48\nomitting the Hubbard U correction, and whether any test calculations were conducted to assess its potential impact on the electronic structure and total energy?\nResponse 4-2: We would like to thank the reviewer for the valuable comments. In the DFT calculations, we have revised the Gibbs free energy results by applying the Hubbard U correction. Specifically, test calculations were conducted by applying Hubbard U corrections to Co (U = 3.32 eV, Nat. Catal. 2024, 7, 1213) and Ni (U = 6.20 eV, Nat. Catal. 2024, 7, 1213). We have updated the calculation results in the manuscript and added the relevant descriptions in the theoretical simulation section.\nRelated Revision:\n(Manuscript, page 18)\nTo accurately describe the strong electron correlation effects in transition metals, the DFT+U method was employed with Hubbard U parameters of 3.32 eV for Co, 6.20 eV for Ni, and 5.80 eV for Ti 52,53. The empirical dispersions of Grimme (DFT-D3) were applied to account for the long-range van der Waals interactions 49.\n(Manuscript, page 29)\n2 8 8\n50\n(Manuscript, page 12–14)\nFinally, we analyzed the influence of amorphous/crystalline interface in A/C-CoNiS on catalytic reaction kinetics by DFT calculations. As shown in Fig. 5a, the atomic structure covers two parts, the amorphous structure (marked with Amor-A/C-CoNiS) generated by Sn doping, and the side parts with crystalline structure (Cryst-A/C-CoNiS). Fig. 5b shows the model of C-CoNiS with only crystalline structure for comparison. Because there are two parts in Fig. 5a, we had to select active sites from both amorphous and crystalline regions. Specifically, we screened multiple possible sites and identified the one with the lowest S adsorption energy as the optimal active site (Supplementary Figs. 27–29). As shown in Figs. 5c and 5d, the rate-determining step (RDS) from Na S to Na S shows a free energy value of 0.36 eV for C-CoNiS, which decreases to 0.25 eV for Amor-A/C-CoNiS and 0.27 eV for Cryst-A/C-CoNiS. That is, not only the amorphous region (Fig. 5c) but also the nearby crystalline region (Fig. 5d) in A/C-CoNiS show decreased energy barrier for NaPSs conversion. As shown in Figs. 5e and 5f, the climbing-image nudged elastic band (CI-NEB) calculations reveal that the decomposition barrier of Na S is significantly reduced from 0.77 (C-CoNiS) to 0.58 eV (Amor-A/C-CoNiS) and 0.68 eV (Cryst-A/C-CoNiS). The structural evolution of Na S decomposition is provided in Supplementary Figs. 30. Notably, both the amorphous regions and the neighboring crystalline regions of A/C-CoNiS facilitate Na S decomposition by lowering the energy barrier 50. These studies verify that the amorphous/crystalline interface generated by Sn doping optimize both local electronic microenvironment of metal sites in both amorphous and crystalline regions.\n8 2 2 2 2 2\nComment 4-3: In the DFT investigation of the A/C-CoNiS interface and its role in catalytic reaction kinetics, how did the authors determine the specific active site(s) for Na–S adsorption, particularly considering the structural heterogeneity and potentially numerous adsorption sites present in the amorphous region? Given that amorphous structures can host a variety of chemically distinct sites, was any systematic approach like energy screening was employed to identify the most representative or catalytically relevant sites?\nResponse 4-3: We sincerely appreciate the reviewer’s valuable comments. A systematic screening of candidate sites on the C-CoNiS and A/C-CoNiS was conducted to precisely determine the possible adsorption sites relevant to catalysis. To rationally reduce complexity, we first grouped atoms into equivalent categories by comparing their charge values, where atoms with nearly identical charge numbers were considered to belong to the same chemical environment. Within each category, representative atoms were selected, and their adsorption energies toward S were calculated (adsorption energies and adsorption configurations are shown in Supplementary Figs. 25–27). Among these, the site with the lowest adsorption energy was identified as the most catalytically relevant active site. We have added the relevant discussion in the revised manuscript and SI.\n(Manuscript, page 13)\nSpecifically, we screened multiple possible sites and identified the one with the lowest S adsorption energy as the optimal active site (Supplementary Figs. 27–29).\n8\n(Supplementary information, page 32–34)\n8\n8\n8 8\nComment 4-4: (a) The results indicate that the amorphous region of the A/C-CoNiS system exhibits the highest binding energies for Na–S adsorption compared to the crystalline counterpart. Could the authors provide further insights into the underlying factors responsible for these enhanced adsorption energies at the amorphous sites? A detailed discussion on the bonding nature—such as charge transfer characteristics, local coordination environments, or electronic structure analysis—would greatly aid in understanding the origin of the stronger interaction.\n55\n(b) Was any assessment of the system’s electronic conductivity performed to evaluate its influence on the overall catalytic performance? Given that electronic transport plays a crucial role in redox kinetics, such analysis would be of significant value.\n(c) In addition, the manuscript briefly mentions Sn doping in the catalyst. Could the authors elaborate on the specific role of Sn in modifying the catalyst’s properties? In particular, does Sn incorporation induce any notable changes in the electronic structure or charge redistribution that could influence Na–S adsorption or reaction kinetics?\nResponse 4-4: We appreciate the reviewer’s insightful comment.\n(a) We examined the charge density differences during Na S adsorption. As illustrated in Fig. 5i, a more substantial charge transfer occurs on A/C-CoNiS, which is indicative of stronger electronic interactions. The result suggests that the unique local coordination and structural disorder of the amorphous regions strengthen polysulfide binding, thereby explaining the higher adsorption energies and more effective shuttle suppression observed for A/C-CoNiS (Adv. Mater. 2024, 36, 2411725).\n(b) Four-probe measurements were conducted to determine the intrinsic conductivities of the catalysts, which were found to be 61.0 S m−1 for A/C-CoNiS and 50.7 S m−1 for C-CoNiS. The higher conductivity of A/C-CoNiS can be attributed to the presence of a small amount of MXene, which possesses high intrinsic conductivity (Nano-Micro Lett. 2025, 17, 93), and a greater concentration of sulfur vacancies (Angew. Chem. Int. Ed. 2024, e202404816) in A/C-CoNiS, both of which facilitate electron transport.\n(c) We performed differential charge density analysis for Sn-doped A/C-CoNiS. As shown in Fig. R9, introduction of Sn leads to electron gain by neighboring Co and Ni atoms, consistent with XPS observations (decreased Co/Ni valence). Sn doping induces pronounced charge delocalization, especially in the amorphous regions, creating highly active sites that enhance adsorption effect and improve redox kinetics (Adv. Mater. 2025, 2506839).\n2 6\nComment 4-5: The reversibility of the Na–S battery is a critical parameter influencing long-term performance. In this context, could the authors provide insights into the sodium diffusion mechanism during the charging process? Specifically, how does the Na–S bond cleavage proceed on the catalyst surface, and what are the associated kinetic barriers? It would be helpful if the authors could support their discussion with a kinetic analysis—such as nudged elastic band (NEB) calculations—to quantify the energy barriers involved in Na diffusion and bond dissociation. Was such an analysis performed or considered?\nResponse 4-5: We sincerely appreciate the reviewer’s constructive suggestion. To elucidate the energy barrier associated with Na S decomposition, we performed climbing-image nudged elastic band (CI-NEB) calculations. The decomposition energy barriers of Na S on Amor-A/C-CoNiS, Cryst-A/C-CoNiS, and C-CoNiS are calculated to be 0.58 eV, 0.68 eV, and 0.77 eV, respectively (Figs. 5e and 5f). These results suggest that A/C-CoNiS, with its abundant catalytically active sites, can more effectively facilitate the cleavage of Na–S bonds, thereby accelerating the oxidative decomposition of Na S. The calculation results further confirm the enhanced electrocatalytic activity of A/C-CoNiS. According to the reviewers’ comments, we added NEB energy profiles and relevant discussion in the revised manuscript.\n2 2 2\nRelated Revision:\n57\n(Manuscript, page 13)\nAs shown in Figs. 5e and 5f, the climbing-image nudged elastic band (CI-NEB) calculations reveal that the decomposition barrier of Na S is significantly reduced from 0.77 (C-CoNiS) to 0.58 eV (Amor-A/C-CoNiS) and 0.68 eV (Cryst-A/C-CoNiS). The structural evolution of Na S decomposition is provided in Supplementary Fig. 30. Notably, both the amorphous regions and the neighboring crystalline regions of A/C-CoNiS facilitate Na S decomposition by lowering the energy barrier 50.\n2 2 2\n(Supplementary information, page 35)\nSupplementary Fig. 30 | CI-NEB calculation of the dissociation pathway of Na S on the a Amor-A/C-CoNiS, b Cryst-A/C-CoNiS, and c C-CoNiS surface.\nResponse 4-6: We appreciate the reviewer’s insightful comments regarding the interfacial effects of MXene. It is well established that MXene can modulate interfacial electronic\n58\nstructures at the nanoscale. Our previous work shows that 5 nm NiCoP nanoparticles on MXene nanosheets exhibit strong interfacial coupling, optimizing surface adsorption and accelerating intermediate conversion (ACS Nano 2022, 16, 11049−11058). However, the catalyst particles in our work are approximately 800 nm in diameter and supported on MXene sheets, resulting in limited interfacial contact. Consequently, charge transfer between catalyst and substrate is significantly weakened and not the dominant factor. In addition, the main role of MXene is to provide steric hindrance to induce the formation of multipods catalyst morphology. The key innovation of this work lies in the precise engineering of the catalyst’s intrinsic structure—specifically the synergy between amorphous/crystalline interfaces and hierarchical architecture construction—to enhance catalytic activity, rather than the modulating effect of MXene on the catalytic performance of sulfides. Based on the above considerations, to better align with the structural characteristics of the material, we do not discuss the electronic interactions between MXene and the catalyst.\nThank you for reading this letter. We are grateful to the editor for providing us with the opportunity to further revise our manuscript, and we extend our heartfelt thanks to all reviewers for their constructive comments and positive evaluations. To address the points raised by Reviewer #1, we have added comparative SEM images and additional electrochemical measurements with varying catalyst-to-cathode ratios. We have carefully considered all feedback and revised the manuscript and Supplementary Information accordingly.\nReviewer #1 (Remarks to the Author):\nGeneral Comments: The revised manuscript has well addressed my questions. I recommend it for publication pending the following supplementary information:\nResponse: Thank you for your positive evaluation and constructive comments. We respond to your comments one by one as follows. Thanks again.\nComment 1-1: Does Sn doping induce morphological changes in CoNiS? Comparative SEM analysis before and after doping is required.\nResponse 1-1: We thank the reviewer for this valuable suggestion. Sn doping indeed induces noticeable morphological changes in CoNiS. As shown in Supplementary Fig. 8, the pristine CoNiS consists of interconnected spherical particles with an average diameter of approximately 1 μm. After Sn incorporation, the material evolves into a unique multipod structure, accompanied by interwoven crystalline and amorphous domains (Fig. 1b and Supplementary Fig. 3a). These results confirm that Sn doping plays a critical role in tuning the morphology and structural disorder of CoNiS In response to the reviewer’s comment, we have incorporated\n1\nrelated SEM characterization into the revised manuscript and Supplementary Information, together with the relevant discussion, to provide a more complete and direct morphological comparison.\nRelated Revision:\n(Manuscript, page 5)\nIt’s interesting to find that Sn introducing not only induces the formation of unique multipod structure, but also leads to the interwoven crystalline and amorphous structure.\n(Supplementary information, page 4)\nSupplementary Fig. 3 | Characterizations of A/C-CoNiS. a SEM image and b XRD pattern of A/C-CoNiS. Supplementary Fig. 3a exhibits a distinctive multipod morphology with radially extended branches. In Supplementary Fig. 3b, the diffraction peaks match well with cubic Co S with planes of (111), (311), (222), (331), (511), and (440) (JCPDS No. 19-0364). The synthesized (CoNi) S by adding nickel elements has the same atomic structure as that of Co S . The low degree of crystallinity indirectly confirms the amorphous-crystalline interwoven structure.\n9 8 9 8 9 8\n(Supplementary information, page 8)\n9 8\nComment 1-2: What is the catalyst-to-cathode ratio? Is this the optimal ratio? Additional electrochemical performance data with varying catalyst ratios should be provided.\nResponse 1-2: We thank the reviewer for this insightful comment. The catalyst-to-cathode ratio used is 3:7, derived from the sulfur content (70 wt%) of the A/C-CoNiS/S composite employed during cathode fabrication (see “Preparation of sulfur cathodes” section). To address the reviewer’s concern, we added the cycling performance at 1 A g−1 for cathodes with sulfur contents of 60, 80, and 90 wt%, corresponding to catalyst-to-cathode mass ratios of 4:6, 2:8, and 1:9, respectively (Supplementary Fig. 11). The results reveal no appreciable capacity difference at sulfur loadings of 60 % and 70 %. However, once the sulfur content reaches 80 % or 90 %, a discernible capacity fade is observed. While preserving the specific capacity, increasing the sulfur loading as much as possible is beneficial for enhancing the overall capacity and energy density of the cell. Therefore, we selected a sulfur loading of 70 wt%, which corresponds to a catalyst-to-cathode mass ratio of 3:7. The related discussion has been added to the revised manuscript and Supplementary Information.\n(Manuscript, page 6)\nSupplementary Fig. 11 shows that A/C-CoNiS/S achieves its optimal electrochemical performance at a sulfur loading of 70 wt%, while the maximum sulfur loading of C-CoNiS/S is 65 wt%.\n(Supplementary information, page 13)\nSupplementary Fig. 11 | a TGA profiles of A/C-CoNiS/S. b Cycling performance of A/C-CoNiS/S at sulfur loadings of 60 wt%, 70 wt%, 80 wt%, and 90 wt%. c TGA profile of C-CoNiS/S. TGA tests were conducted over the temperature range of 30 to 400 °C with a heating rate of 10 °C min−1. No significant mass loss was observed before 55 °C. The rapid weight loss observed between 150 and 350 °C is attributed to the volatilization of sulfur. TGA measurements on A/C-CoNiS/S prepared at 9:1, 8:2, 7:3, and 6:4 mass ratios yield sulfur loadings of 90, 80, 70, and 60 wt%, respectively. Electrochemical cycling at 1 A g−1 (Supplementary Fig. 11b) shows that A/C-CoNiS/S with sulfur loadings of 60, 70, 80, and 90 wt% delivers capacities of 1419.9, 1417.0, 1323.6, and 1269.1 mAh g−1 after 50 cycles The results clearly show reveal no appreciable capacity difference at sulfur loadings of 60 % and 70 %. However, once the sulfur content reaches 80 % or 90 %, a discernible capacity fade is observed. Therefore, we selected a sulfur loading of 70 % for A/C-CoNiS/S. Furthermore, TGA measurement on C-CoNiS/S prepared at a 7:3 mass ratio show that the sulfur loading is only 65 wt% due to its limited adsorption capability (Supplementary Fig. 11c).\n4"}, {"round": 2, "reviewer_comments": {"reviewer_1": "The revised manuscript has well addressed my questions. I recommend it for publication pending the following supplementary information:\n1. Does Sn doping induce morphological changes in CoNiS? Comparative SEM analysis before and after doping is required.\n2. What is the catalyst-to-cathode ratio? Is this the optimal ratio? Additional electrochemical performance data with varying catalyst ratios should be provided.", "reviewer_2": "The issues I concerned have been addressed by the authors, and the overall quality of the manuscript has been obviously improved. In my opinion, the currenct manuscript can be accepted for publication on Nature Communications now.", "reviewer_3": "The author has addressed all my concerns; the manuscript is now acceptable for publication.", "reviewer_4": "The authors have satisfactorily addressed all comments. I recommend the manuscript be accepted for publication in its current form"}, "author_response": "Response Letter for Manuscript “Amorphous-crystalline interwoven multipods with high Co/Ni activity for sodium-sulfur battery operated from −20 to 50 °C”\nThank you for reading this letter. We are grateful to the editor for providing us with the opportunity to further revise our manuscript, and we extend our heartfelt thanks to all reviewers for their constructive comments and positive evaluations. To address the points raised by Reviewer #1, we have added comparative SEM images and additional electrochemical measurements with varying catalyst-to-cathode ratios. We have carefully considered all feedback and revised the manuscript and Supplementary Information accordingly.\nReviewer #1 (Remarks to the Author):\nGeneral Comments: The revised manuscript has well addressed my questions. I recommend it for publication pending the following supplementary information:\nResponse: Thank you for your positive evaluation and constructive comments. We respond to your comments one by one as follows. Thanks again.\nComment 1-1: Does Sn doping induce morphological changes in CoNiS? Comparative SEM analysis before and after doping is required.\nResponse 1-1: We thank the reviewer for this valuable suggestion. Sn doping indeed induces noticeable morphological changes in CoNiS. As shown in Supplementary Fig. 8, the pristine CoNiS consists of interconnected spherical particles with an average diameter of approximately 1 μm. After Sn incorporation, the material evolves into a unique multipod structure, accompanied by interwoven crystalline and amorphous domains (Fig. 1b and Supplementary Fig. 3a). These results confirm that Sn doping plays a critical role in tuning the morphology and structural disorder of CoNiS In response to the reviewer’s comment, we have incorporated\n1\nrelated SEM characterization into the revised manuscript and Supplementary Information, together with the relevant discussion, to provide a more complete and direct morphological comparison.\nRelated Revision:\n(Manuscript, page 5)\nIt’s interesting to find that Sn introducing not only induces the formation of unique multipod structure, but also leads to the interwoven crystalline and amorphous structure.\n(Supplementary information, page 4)\nSupplementary Fig. 3 | Characterizations of A/C-CoNiS. a SEM image and b XRD pattern of A/C-CoNiS. Supplementary Fig. 3a exhibits a distinctive multipod morphology with radially extended branches. In Supplementary Fig. 3b, the diffraction peaks match well with cubic Co S with planes of (111), (311), (222), (331), (511), and (440) (JCPDS No. 19-0364). The synthesized (CoNi) S by adding nickel elements has the same atomic structure as that of Co S . The low degree of crystallinity indirectly confirms the amorphous-crystalline interwoven structure.\n9 8 9 8 9 8\n(Supplementary information, page 8)\n9 8\nComment 1-2: What is the catalyst-to-cathode ratio? Is this the optimal ratio? Additional electrochemical performance data with varying catalyst ratios should be provided.\nResponse 1-2: We thank the reviewer for this insightful comment. The catalyst-to-cathode ratio used is 3:7, derived from the sulfur content (70 wt%) of the A/C-CoNiS/S composite employed during cathode fabrication (see “Preparation of sulfur cathodes” section). To address the reviewer’s concern, we added the cycling performance at 1 A g−1 for cathodes with sulfur contents of 60, 80, and 90 wt%, corresponding to catalyst-to-cathode mass ratios of 4:6, 2:8, and 1:9, respectively (Supplementary Fig. 11). The results reveal no appreciable capacity difference at sulfur loadings of 60 % and 70 %. However, once the sulfur content reaches 80 % or 90 %, a discernible capacity fade is observed. While preserving the specific capacity, increasing the sulfur loading as much as possible is beneficial for enhancing the overall capacity and energy density of the cell. Therefore, we selected a sulfur loading of 70 wt%, which corresponds to a catalyst-to-cathode mass ratio of 3:7. The related discussion has been added to the revised manuscript and Supplementary Information.\n(Manuscript, page 6)\nSupplementary Fig. 11 shows that A/C-CoNiS/S achieves its optimal electrochemical performance at a sulfur loading of 70 wt%, while the maximum sulfur loading of C-CoNiS/S is 65 wt%.\n(Supplementary information, page 13)\nSupplementary Fig. 11 | a TGA profiles of A/C-CoNiS/S. b Cycling performance of A/C-CoNiS/S at sulfur loadings of 60 wt%, 70 wt%, 80 wt%, and 90 wt%. c TGA profile of C-CoNiS/S. TGA tests were conducted over the temperature range of 30 to 400 °C with a heating rate of 10 °C min−1. No significant mass loss was observed before 55 °C. The rapid weight loss observed between 150 and 350 °C is attributed to the volatilization of sulfur. TGA measurements on A/C-CoNiS/S prepared at 9:1, 8:2, 7:3, and 6:4 mass ratios yield sulfur loadings of 90, 80, 70, and 60 wt%, respectively. Electrochemical cycling at 1 A g−1 (Supplementary Fig. 11b) shows that A/C-CoNiS/S with sulfur loadings of 60, 70, 80, and 90 wt% delivers capacities of 1419.9, 1417.0, 1323.6, and 1269.1 mAh g−1 after 50 cycles The results clearly show reveal no appreciable capacity difference at sulfur loadings of 60 % and 70 %. However, once the sulfur content reaches 80 % or 90 %, a discernible capacity fade is observed. Therefore, we selected a sulfur loading of 70 % for A/C-CoNiS/S. Furthermore, TGA measurement on C-CoNiS/S prepared at a 7:3 mass ratio show that the sulfur loading is only 65 wt% due to its limited adsorption capability (Supplementary Fig. 11c).\n4"}]

Decision letter