NC@Bi₂S₃ Nanospheres as High-Performance Anode Materials for Lithium-Ion Batteries

Bi₂S₃ holds immense potential to be promoted as an anode material for lithium-ion batteries (LIBs), owing to the high theoretical gravimetric and volumetric capacities. However, the poor electrical conductivity and volume expansion during cycling hinder the practical applications of Bi₂S₃. Therefore, through subsequent heat treatment, the nitrogen-doped carbon film was successfully loaded on the nanosphere Bi₂S₃, which we call nitrogen-rich carbon layer-coated Bi₂S₃ (NC@Bi₂S₃). Hence, the nanosphere Bi₂S₃ uniformly covered by a nitrogen-rich carbon layer was successfully coated on the Bi₂S₃ surface (NC@Bi₂S₃) through post-treatment. Due to the effective interaction between glutathione and inorganic materials, dopamine hydrochloride molecules are introduced and polymerized on the surface of the spherical Bi₂S₃ structure and then converted into a nitrogen-rich carbon layer with an average thickness of 10.0 nm. The electrochemical tests reveal that the discharge specific capacities of Bi₂S₃ and NC@Bi₂S₃ reach 340.99 and 645.13 mAh/g after 300 cycles at 100 mA/g, respectively. Kinetic analysis shows that the contribution of pseudocapacitance behavior increases by about 10% after the nitrogen-rich carbon layer is coated. These results suggest the potential of NC@Bi₂S₃ as a high-performance anode material for LIBs; the stability can be enhanced by core-shell structures.