Preparation of Na3V2(PO4)3 sodium-ion battery cathode material

Abstract

The polyanionic sodium vanadium phosphate (Na3V2(PO4)3) cathode materials have many electrochemical applications because they have a stable lattice structure, high structural stability, good theoretical specific energy, a stable voltage plateau, and high thermodynamic stability. In this study, the sol–gel method was used to prepare carbon-coated Na3V2(PO4)3/C (NVP/C) sodium-ion cathode materials. The synthesis conditions of different ratios of sodium and carbon sources were investigated. In addition, extractable elements (B, Cl, etc.) from brine were doped into NVP/C to improve the electrical conductivity of the electrode materials. SEM, XRD, EDX, charge/discharge test, and cyclic voltammetry characterizations were used to evaluate the morphology, element distribution, and the electrochemical performance of the modified materials. The results showed that the prepared samples are pure phases with small and uniform particle sizes, which are more favorable for sodium-ion de-embedding and improving the electrochemical properties of the materials. The electrochemical properties of the experimentally prepared B-NVP/C and Cl-NVP/C were all improved compared to the pure phase NVP/C.