Enhanced sodium ion storage performance of Na3V2(PO4)3 with N-doped carbon by folic acid as carbon-nitrogen source

Na3V2(PO4)3/nitrogen doped carbon (NVP/CN) composites have been fabricated by a simple and low cost solid-state technique using folic acid as the carbon-nitrogen source. The structure, morphology and electrochemical performance of NVP/CN composites coated with various carbon-nitrogen layer contents are well investigated. The results reveal that the NVP/CN composite with 3.3 wt% carbon-nitrogen exhibits the largest specific surface area, with a uniform carbon-nitrogen layer thickness of approximately 2 nm. When tested as cathode material for sodium ion battery, NVP/CN composite with 3.3 wt% carbon-nitrogen displays an outstanding high rate properties with the discharge capacity of 95 and 91 mAh g−1 at 10 and 20 C, respectively, and long cycle life up to 3000 times even at a high rate of 10 C due to the smallest charge-transfer resistance and highest Na+ diffusion coefficient. The results suggest that folic acid is a promising carbon-nitrogen source for construction of NVP/CN and other cathode materials.