Nitrogen-Doped Graphene-Supported Straw-Like CoSe₂ for Rapid and Stable Sodium-Ion Storage

Cobalt diselenide (CoSe₂) materials exhibit significant potential in sodium-ion batteries (SIBs) owing to their high theoretical specific capacity and excellent cycling stability. However, the conductivity and volume expansion of CoSe₂ limit its rate performance and cycling stability. Herein, a nitrogen-doped reduced graphene oxide (N-rGO) supported straw-like CoSe₂ anode material (CoSe₂/N-rGO) is synthesized via a hydrothermal method. Experimental results show that nitrogen doping improves the conductivity and structural stability of CoSe₂/N-rGO, enabling excellent rate performance (311.75 mAh g^-1 at 10 A g^-1) and high cycling stability (356.78 mAh g^-1 after 1000 cycles at 1 A g^-1). Notably, the CoSe₂/N-rGO||NVP full cell exhibits a capacity of 117.4 mAh g^-1 at 0.1 C, approaching 98.7% of the calculated maximum for NVP (118 mAh g^-1). This approach offers new insights and valuable guidance for the structure of efficient electrode materials for energy storage systems.