Superior Na-storage performance of Na3V2(PO4)3/C-Ag composites as cathode material for Na-ion battery

Na3V2(PO4)3(NVP) is supposed to be a generation cathode material for sodium-ion batteries due to its unique 3D channel structure and remarkable thermal stability. But its poor electronic conductivity partly impedes their electrochemical performance. Herein, a sequence of Na3V2(PO4)3/C-Ag(NVP/C-Ag) samples were manufactured via a traditional one-step solid-state process to alleviate this problem. The results reveal that NVP/C-Ag-2 sample possesses minimum charge-transfer resistance and maximum ion diffusion coefficient, and thus has satisfactory electrochemical performance, with a capacity of 95 mA h/g at 10C and almost no capacity decay after 500 cycles. Even at 50C, it can reach a reversible specific capacity of 85 mA h/g. The results demonstrate that an appropriate ratio of silver and carbon acting cooperatively on the particles is a valid method to enhance the electrochemical property.