Hierarchical NiCo2S4 hollow spheres as a high performance anode for lithium ion batteries

Abstract

Hierarchical NiCo₂S₄ hollow spheres are successfully fabricated by a facile hydrothermal method accompanied by a high-temperature annealing and anion exchange process. By using NiCo₂S₄ hollow spheres as an anode material for lithium ion batteries, a high specific capacity of 696 mA h g⁻¹ can be obtained after 100 cycles at a current density of 200 mA g⁻¹. Even at a current density of 2000 mA g⁻¹, the specific capacity still remains at 411 mA h g⁻¹ after 50 cycles. The good electrochemical performance can be attributed to the unique porous features and void spaces within the surface of the hollow spheres, which provide large contact areas between the electrolyte and active materials for electrolyte diffusion and alleviate the volume change during the lithium-ion insertion/extraction process.