Entropy‐Change Driven Highly Reversible Sodium Storage for Conversion‐Type Sulfide

Abstract Transition metal sulfides (TMSs) are reported to be efficient sodium storage anode materials due to their rich redox chemistry and good electronic conductivity features. However, the issues of poor reaction reversibility and cyclability, caused by structure degradation and volume expansion during repeated (de)sodiation processes, have far limited the applicability of these materials. Herein, a high‐entropy configuration strategy is reported for Cu 4 MnFeSnGeS 8 anodes for advanced sodium ion batteries. In this high‐entropy material, the homogeneously dispersed cations can effectively suppress the continuous coarseness of Sn nanoparticles and maintain valid interface contact between M 0 and Na 2 S, thus achieving highly reversible sodium storage. Moreover, the highly reversible crystalline‐phase transformation of high‐entropy Cu 4 MnFeSnGeS 8 and highly inherent mechanical stability can effectively relieve the persistently accumulated mechanical stress, thus restraining continuous breakage of the solid electrolyte interphase film and pulverization of the electrode, and improving cycling stability. Furthermore, when coupled with a Na 3 V 2 (PO 4 ) 3 cathode, the full cell shows a high energy density (264 Wh kg –1 ), which makes the high‐entropy‐stabilized sulfide a promising anode candidate for SIBs.