CoSbS and its hard carbon-containing nanocomposite (CoSbS@hard-C) are prepared via simple solid-state reactions, and their potential as Na-ion battery (NIB) anode materials is investigated. The electrochemical phase change mechanism of CoSbS during Na insertion/extraction is thoroughly investigated using various ex situ analytical tools. During Na insertion, the CoSbS undergoes a topotactic transformation owing to the formation of a Na_xCoSbS (x ≤ 1.6), and then, it is converted into Na₃Sb, Na₂S, and Co in the fully Na-inserted state via a conversion reaction. Conversely, during Na extraction, Na₃Sb transforms to Sb, which alloys with Co to form CoSb. In the fully Na-extracted state, CoSb and S from Na₂S are recombined into CoSbS. Owing to the interesting reaction mechanism of CoSbS, the electrochemical performance of the CoSbS and CoSbS@hard-C anodes is excellent. Specifically, when CoSbS is used as a NIB anode, the topotactic transformation between CoSbS and Na_xCoSbS (x ≤ 1.6) leads to stable cycling behavior of the NIB and a volumetric capacity of ~480 mAh cm⁻³ is retained after 100 cycles. Additionally, the NIB with the CoSbS@hard-C anode presents highly reversible and stable capacity (~570 mAh cm⁻³ after 150 cycles) and fast rate capability (~500 and ~450 mAh cm⁻³ at 2C and 5C, respectively), which can be attributed to the presence of uniformly dispersed small (5–8 nm) CoSbS nanocrystallites in the hard carbon matrix. Therefore, CoSbS can be utilized as a new anode material for high-performance NIBs.

通过简单的固相反应制备了CoSbS及其含硬碳纳米复合材料（CoSbS @ hard-C），并研究了其作为Na离子电池（NIB）负极材料的潜力。使用各种非原位分析工具彻底研究了CoSbS在Na插入/萃取过程中的电化学相变机理。在Na插入时，CoSbS经历由于中的Na的形成的局部规整变换_X CoSbS（X ≤1.6），然后，将其转换成Na ₃锑，钠₂通过S和Co在完全的Na-插入状态转化反应。相反，在Na提取过程中，Na ₃Sb转变为Sb，然后与Co合金化形成CoSb。在完全提取Na的状态下，来自Na ₂ S的CoSb和S重新结合为CoSbS。由于CoSbS有趣的反应机理，CoSbS和CoSbS @ hard-C阳极的电化学性能非常好。具体地，当CoSbS用作NIB阳极，CoSbS和Na之间的局部规整变换_X CoSbS（X ≤1.6）通向NIB的稳定的循环行为和〜480毫安cm的体积容量^-3是100次循环后保留。此外，带有CoSbS @ hard-C阳极的NIB具有高度可逆和稳定的容量（150次循环后约570 mAh cm ^-3）和快速速率能力（约500和约450 mAh cm ^-3）分别位于2C和5C），这可以归因于硬碳基质中均匀分散的小（5-8 nm）CoSbS纳米微晶的存在。因此，CoSbS可以用作高性能NIB的新阳极材料。