Heterostructured Bi@Bi2O3 nanoparticles bonding on reduced graphene oxide with high-rate capability and outstanding cycling stability for sodium-ion batteries

Abstract

Alloy-based anode materials for sodium-ion batteries (SIBs) are promising due to their high theoretical capacity and abundant resources. However, they suffer from significant volume expansion and aggregation during sodiation process, leading to severe capacity fading and inferior cycling stability. Herein, Bi@Bi₂O₃ with heterostructures and rGO coating via coordination-driven self-assembly, carbonization, and local oxidation process is proposed. The built-in electric field constructed by heterostructures significantly promotes charge transfer and improves reaction kinetics. Additionally, the confinement effect of rGO not only enhance the electronic conductivity but also alleviates the volume expansion effectively. As a result, the Bi@Bi₂O₃-rGO anode exhibits high reversible capacity (480.1 mAh g⁻¹ at 0.1 A g⁻¹), excellent rate capability (287.7 mAh g⁻¹ at 10 A g⁻¹), and long-term stability (253.3 mAh g⁻¹ after 2000 cycles at 2 A g⁻¹). The enhanced reaction kinetics are systematically probed by series of tests combined with theoretical calculations. This strategy offers valuable insights of designing alloy-based anodes for SIBs with high electrochemical performance.