Engineering hierarchically ZnS/NiS/NiS 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/NiS 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/NiS. 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/NiS 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 after 300 cycles at 2 A·g. 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.