Graphene-like ultrathin bismuth selenide nanosheets as highly stable anode material for sodium-ion battery

Sodium-ion batteries have high potential for next-generation battery system because of their cost-effective and similar energy-storage mechanism to lithium-ion batteries. However, the commercial graphite anode for lithium-ion batteries cannot be applied to sodium-ion batteries. The lower rate performance and poor cycling life of existing anode materials are major bottlenecks to prospective application in sodium-ion batteries. To address this issues, we synthesize a novel ultrathin Bi2Se3 layered nanosheets that enhance sodium-ion storage performance due to its stable graphene-like structure. Benefiting from the layered nanosheets morphology, as-prepared anode material exhibit excellent electrochemical performance, which can deliver an initial high capacity of 650 mA h g−1 (Na+ storage) at 0.1 A/g along with outstanding stability. The ultrathin Bi2Se3 layered nanosheets with a thickness of ~6 nm offer a large electrode-electrolyte contact interface due to its porous morphology. Ex-situ transmission electron microscopy analysis and electrochemical impedance spectroscopy measurement reveals the structural stability of bismuth selenide nanosheets during repeated sodium-ion insertion and extraction process. The superior electrochemical performance and unique graphene-like architecture of the layered bismuth selenide nanosheets offer a promising anode for commercial sodium-ion batteries.