High-entropy metal sulfoselenide with enhanced kinetics and stable cyclic performance for electrochemical lithium storage

Various metal sulfides have been widely investigated as anodes for Li-ion batteries due to their high specific capacity. However, they suffer from the low reversibility of conversion reactions and large volume expansion during lithiation/delithiation, leading to poor rate capability and rapid capacity decay. High-entropy metal sulfides, as anode materials, have garnered significant attention due to their excellent electrochemical performance. In this work, a novel high-entropy metal sulfoselenide, (FeCoNiMoV)₉(SSe)₈ with the molar ratio of S:Se=0.9:0.1, was designed and synthesized via a modified glycerol-assisted template method. It was found that the (FeCoNiMoV)₉(SSe)₈ adopted the single-phase structure of the Co₉S₈ lattice, the configurational entropy of which was significantly increased by incorporating the different metal cations and Se anion, thereby enhancing the cocktail effect and electrode kinetics for electrochemical lithium storage. In addition, incorporating Se anion could improve the electronic conductivity, ion diffusion and enhance the reversibility of conversion reaction. Therefore, the (FeCoNiMoV)₉(SSe)₈ exhibited rapid kinetics and excellent long-cycle stability for electrochemical lithium storage. At the current density of 5.0 A∙g^–1, the (FeCoNiMoV)₉(SSe)₈ delivered a reversible specific capacity of 669 mAh∙g^–1, demonstrating its good high-rate capability. After 1120 cycles, it could still retain a reversible specific capacity of 643 mAh∙g^–1 at 5.0 A∙g^–1, with the capacity retention of 93.5%. Its excellent performance of electrochemical lithium storage was mainly contributed to the synergistic effect of the different metal cations and S/Se anions and high-entropy enhanced electrode kinetics.