Boosting the rate capability of heteroatom co-doped graphene-supported Na3V2(PO4)3 as cathode material for sodium-ion battery full cell

The development of Na3V2(PO4)3 (NVP) has been hindered by challenges such as poor conductivity and volume collapse. To address these issues, nitrogen- and sulfur-co-doped reduced graphene oxide (NSrGO) sheetdecorated NVP was synthesized and incorporated into the carbon conductive network of the cathode material to enhance the performance of sodium-ion batteries. Different amounts of NSrGO (5, 10, and 20 wt.%) were used to decorate NVP microspheres through a ball milling technique. Characterization of the samples was conducted using SEM, TEM, XPS, XRD, and TGA. The results indicated that the NVP-NSrGO composite, containing 10 wt.%, performed exceptionally well. NSrGO exhibited excellent rate performance and cycling stability, with a discharge capacity of 144 mAh g- 1 at a rate of 0.1 C and a capacity retention of 91.6 % after 100 cycles at 1 C. The BB5CNT||NVP-10NSrGO full cell demonstrated an impressive discharge capacity of 98.3 mAh g- 1 at 0.1 C and a long cycle life of up to 2000 cycles at an ultrahigh rate of 10 C, due to reduced charge transfer resistance and a higher diffusion coefficient for Na+ in the NVP-10NSrGO electrode. This strategy of coating NVP combinations with N- and S-co-doped rGO provides a promising approach for improving cathode materials.