Engineering hierarchically ZnS/NiS/NiS₂ hollow porous urchin-like composite towards exceptional lithium storage

Complex hollow structure nanostructure is regarded as the desired approach to alleviating the volume change of lithium-ion batteries (LIBs). In this work, ZnS/NiS/NiS₂ composite with a distinctive hierarchical hollow porous urchin-like structure was prepared through pyrolysis of bimetal-organic frameworks obtained by one-step solvothermal and firstly used as anodes for LIBs. Varying the metal molar ratios allows the control of the surface area and pore size distribution of ZnS/NiS/NiS₂. The obtained composite with a hollow porous urchin-like structure exhibits high porosity, large specific surface area, and strong synergetic interaction between ZnS and NiS/NiS₂ can greatly buffer the volume expansion to keep the mechanical stability, ensure sufficient contact region between electrolyte and electrodes and shorten the Li⁺ transfer distance, meanwhile, the carbon derived from organic ligand of bimetal-organic frameworks also constructs the conductive matrix to accelerate electrons transfer. Based on the above outstanding properties, the obtained material delivers excellent rate capacity, superior reversible capacity, and long-cycle stability, especially disclosing a capacity of 615 mAh·g^-1 after 300 cycles at 2 A·g^-1. This work proposes a feasible strategy to obtain a unique hollow porous urchin-like structure through pyrolysis of bimetal organic frameworks, it can be extended to fabricate other mixed metal sulfides nanostructures with excellent electrochemical performances.