Pressure‐Stabilized High‐Entropy (FeCoNiCuRu)S2 Sulfide Anode toward Simultaneously Fast and Durable Lithium/Sodium Ion Storage

Abstract Pressure‐stabilized high‐entropy sulfide (FeCoNiCuRu)S 2 (HES) is proposed as an anode material for fast and long‐term stable lithium/sodium storage performance (over 85% retention after 15 000 cycles @10 A g −1 ). Its superior electrochemical performance is strongly related to the increased electrical conductivity and slow diffusion characteristics of entropy‐stabilized HES. The reversible conversion reaction mechanism, investigated by ex‐situ XRD, XPS, TEM, and NMR, further confirms the stability of the host matrix of HES after the completion of the whole conversion process. A practical demonstration of assembled lithium/sodium capacitors also confirms the high energy/power density and long‐term stability (retention of 92% over 15 000 cycles @5 A g −1 ) of this material. The findings point to a feasible high‐pressure route to realize new high‐entropy materials for optimized energy storage performance.