NiS/hollow carbon sphere composites for high-performance and long-life Lithium-ion battery anodes

Transition metal sulfides are promising anode materials for LIBs, but are restricted by poor cycle stability and rate performance. In this study, NiS composites with a hollow sphere structure (NiS/HCS) were synthesized for high-performance LIBs using high-temperature carbonization and hydrothermal methods. This structure combines the high specific capacity of NiS and the conductivity of carbonaceous materials. NiS nanoparticles are uniformly distributed on the carbon sphere surfaces, enhancing active site accessibility, while the carbon hollow spheres' inner cavity reduces volume expansion during cycling. The NiS/HCS electrode delivered an initial specific discharge capacity of 982.9 mAh g⁻¹ at 0.2 A g⁻¹ and retained 200.6 mAh g⁻¹ after 500 cycles. Electrochemical kinetic analysis showed a capacitance contribution increase to 69 % at 1.2 mV s⁻¹. The hollow carbon sphere improves conductivity and reduces expansion, while NiS nanoparticles enhance electron transport and electrochemical kinetics. This study offers insights and methods for developing transition metal sulfide-based hollow carbon spheres as high performance anode materials, advancing next-generation LIBs with better efficiency, reliability, and stability.