The intercalation compounds with various electrochemically active or inactive elements in the layered structure have been the subject of increasing interest due to their high capacities, good reversibility, simple structures, and ease of synthesis. However, their reversible intercalation/deintercalation redox chemistries in previous compounds involve a single cationic redox reaction or a cumulative cationic and anionic redox reaction. Here we report an anionic redox chemistry and structural stabilization of layered sodium chromium sulfide. It was discovered that the sulfur in sodium chromium sulfide is electrochemically active, undergoing oxidation/reduction rather than chromium. Significantly, sodium ions can successfully move out and into without changing its lattice parameter c, which is explained in terms of the occurrence of chromium/sodium vacancy antisite during desodiation and sodiation processes. Our present work not only enriches the electrochemistry of layered intercalation compounds, but also extends the scope of investigation on high-capacity electrodes.The rational design of intercalation electrodes is largely confined to the optimization of redox chemistry of transition metals and oxygen. Here, the authors report the single anionic redox process in NaCrS₂ where it is sulfur rather than chromium that works as the electrochemical active species.

中文翻译：

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反位点占据诱导单阴离子氧化还原化学和层状硫化铬钠的结构稳定。


层状结构中具有各种电化学活性或非活性元素的插层化合物由于其高容量、良好的可逆性、结构简单和易于合成而受到越来越多的关注。然而，先前化合物中的可逆嵌入/脱嵌氧化还原化学涉及单一阳离子氧化还原反应或累积的阳离子和阴离子氧化还原反应。在这里，我们报告了层状硫化铬钠的阴离子氧化还原化学和结构稳定性。人们发现，硫化铬钠中的硫具有电化学活性，比铬更容易发生氧化/还原。值得注意的是，钠离子可以在不改变其晶格参数c的情况下成功地移出和移入，这可以通过脱钠和钠化过程中铬/钠空位反位的出现来解释。我们目前的工作不仅丰富了层状插层化合物的电化学，而且扩展了高容量电极的研究范围。插层电极的合理设计很大程度上局限于过渡金属和氧的氧化还原化学的优化。在这里，作者报告了 NaCrS ₂中的单一阴离子氧化还原过程，其中作为电化学活性物质的是硫而不是铬。