Nitrogen-carbon coated Na3V2 (PO4) 2F3 sodium ion positive electrode material and preparation method thereof

The invention discloses a nitrogen and carbon coated Na3V2 (PO4) 2F3 sodium ion positive electrode material and a preparation method thereof. The preparation method comprises the following steps: weighing a proper amount of a sodium source, a vanadium source, a phosphorus source, a fluorine source and citric acid, and carrying out a hydrothermal reaction to obtain an NVPF precursor; dissolving the NVPF precursor and zinc nitrate into deionized water, and marking as a solution a; dissolving 2-methylimidazole and triethylamine into deionized water, and marking as a solution b; slowly adding the solution b into the solution a to obtain an NVPF/ZIF-8 precursor; and finally, placing in a tubular furnace for high-temperature carbonization to obtain the Na3V2 (PO4) 2F3/NC composite material. The nitrogen-carbon-coated Na3V2 (PO4) 2F3 disclosed by the invention is used as the positive electrode material of the sodium ion battery, has high conductivity, and can effectively improve the specific discharge capacity and c