Synthesis of high-entropy metal sulfide FeNiCoCuLiSx for electrochemical lithium storage

Various metal sulfides have been widely investigated as anodes of Li-ion batteries their high specific capacity. However, their low conversion reaction reversibility and repeat volume expansion/contraction during charge-discharge cycling result in poor rate capability and rapid capacity decay. High-entropy sulfides have attracted great attention as novel electrode materials for rechargeable batteries due to their excellent electrochemical performance. This work presented a two-step solvothermal process to synthesis high-entropy sulfide FeNiCoCuLiS_x by means of the glycerol template method. During repeat lithiation/delithiation, the homogeneous dispersion and mixing of the different metal cations could not only effectively suppress the aggregation of metal nanoclusters and coarseness of Li₂S, but also maintain valid interfacial contact between the metal nanoclusters and Li₂S, resulting in significantly improved the conversion reaction reversibility and more cyclic stability. Therefore, FeNiCoCuLiS_x exhibited excellent electrochemical performance for reversible lithium storage, due to its large configurational entropy and multi-component “cocktail effect”. FeNiCoCuLiS_x could deliver a reversible specific capacity as high as 860 mAh g⁻¹ at the current density of 1.0 A g⁻¹ and a high-rate capability of 775 mAh g⁻¹ at 5.0 A g⁻¹. After 1600 cycles, the reversible specific capacity of 826 mAh g⁻¹ remained with a capacity retention of 95.5 % at the current density of 1.0 A g⁻¹, well demonstrating excellent long-cycle stable performance.