Pressure-Stabilized High-Entropy (FeCoNiCuRu)S 2 Sulfide Anode toward Simultaneously Fast and Durable Lithium/Sodium Ion Storage.

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.