High-Performance NiS 2 Hollow Nanosphere Cathodes in Magnesium-Ion Batteries Enabled by Tunable Redox Chemistry.

Two-dimensional metal dichalcogenides have demonstrated outstanding potential as cathodes for magnesium-ion batteries. However, the limited capacity, poor cycling stability, and severe electrode pulverization, resulting from lack of void space for expansion, impede their further development. In this work, we report for the first time, nickel sulfide (NiS 2 ) hollow nanospheres assembled with nanoparticles for use as cathode materials in magnesium-ion batteries. Notably, the nanospheres were prepared by a one-step solvothermal process in the absence of an additive. The results show that regulating the synergistic effect between the rich anions and hollow structure positively affects its electrochemical performance. Crystallographic and microstructural characterizations reveal the reversible anionic redox of S 2- /(S 2 ) 2- , consistent with density functional theory results. Consequently, the optimized cathode (8-NiS 2 hollow nanospheres) could deliver a large capacity of 301 mA h g -1 after 100 cycles at 50 mA g -1 , supporting the promising practical application of NiS 2 hollow nanospheres in magnesium-ion batteries.