Doped multilayer coated iron phosphate-based sodium ion battery positive electrode material and preparation method thereof

The invention provides a doped multi-layer coated iron phosphate-based sodium ion battery positive electrode material and a preparation method thereof. The preparation method comprises the following steps: carrying out ball-milling mixing on iron phosphate dihydrate, a carbon source, a dispersing agent and a solvent to obtain precursor slurry; after drying and grinding, carrying out high-temperature sintering in an inert atmosphere to obtain Fe3 (PO4) 2 (at) C; mixing the Fe3 (PO4) 2 (at) C with Ti3AlC2, a sodium source, a lithium source, a fluorine source and acid, and growing Ti3C2 and AlF3 in situ on Fe3 (PO4) 2 (at) C to form coating; and sintering in an inert atmosphere after drying and grinding, and grinding to obtain the composite material. According to the method, iron phosphate dihydrate and a carbon source are pre-sintered at a high temperature, the graphitization degree of coated carbon is increased, Ti3C2 and AlF3 nanosheets which grow in situ are used for coating, doping of part of lithium elemen