Sodium ion battery polyanion positive electrode material and preparation method thereof

The invention discloses a sodium ion battery polyanion positive electrode material and a preparation method thereof. Potassium ions and ruthenium ions are doped in the pyrophosphate ferric phosphate sodium material at the same time, and the pyrophosphate ferric phosphate sodium material is coated with carbon. The carbon coating layer is used as a conducting layer, the conductivity of the particle surface is improved, meanwhile, the carbon coating layer can inhibit grain growth, and particles with the small particle size are obtained; moreover, in the heat treatment process, Fe < 2 + > can be effectively prevented from being oxidized due to the reducibility of carbon, and the positive electrode material with relatively high purity is obtained. A proper amount of ruthenium doping plays a role in stabilizing the crystal form structure of the material and reducing charge migration resistance of the material, and ruthenium doping enables the material to generate lattice defects and is beneficial to deintercalation