Defective Bi₂S₃ Anchored on CuS/C as an Ultrafast and Long-Life Anode for Sodium-Ion Storage

Due to the high electrical conductivity and abundant redox active sites, bimetal sulfides are highly competitive anode materials for sodium storage with long-life and high-rate. Herein, a heterostructured metal sulfide (Bi₂S₃-CuS) with a carbon-based support is prepared by calcination and ion exchange methods. The synergistic effects of the heterostructure and defective structure provide facile diffusion channels, fast Na⁺ migration, and plentiful active sites for Na⁺, which reflect in the impressive electrochemical performance with a high reversible capacity of 592.2 mA h g^-1 after 1000 cycles at 8 A g^-1. Furthermore, the Na-ion full batteries exhibit an ultra-long cycling performance with a value of 216 mA h g^-1 after 4000 cycles at 10 A g^-1. Interestingly, the defective structure of Bi₂S₃ remains after cycling. Kinetic analyses and density functional theoretical calculations clarified that the heterointerfacial structure, especially on the interface containing sulfur defects in Bi₂S₃ of Bi₂S₃-CuS, could induce feasible ion adsorption and promote ion transfer, which lays the foundation for achieving ultrafast sodiation kinetics.