CoS₂/V₂O₃ heterostructure with coffee ground-derived carbon as superior composite anodes of sodium-ion batteries

The poor ion transport kinetics and serious volumetric change of transition metal sulfides hinder their electrochemical applications. In this study, we introduced a heterostructure between CoS2 and V2O3 as an anode of sodium-ion batteries (SIBs) via a feasible hydrothermal method combining with a biomass carbon derived from coffee grounds (CG). The as-prepared CoS2/V2O3-CG composite retained a reversible capacity of 464.5 mAh g(-1) after 300 cycles at 0.5 A g(-1), which exhibited an excellent rate capability of up to 8 A g(-1) and a remarkable long-cycling life of over 2000 cycles at 2 A g(-1) with a capacity decay rate of less than 0.041% per cycle. The kinetic analysis indicated that CoS2/V2O3-CG composite exhibited a superior capacitive behavior, making it a high Na+ diffusion coefficient in SIBs. The enhanced electrochemical performances of composite can be primarily attributed to the CoS2/V2O3 heterostructure and porous biomass-derived carbon, which offers a built-in electric field and a large surface area and effectively alleviates the volumetric expansion effect.