Preparation method of copper-silver doped lithium iron phosphate positive electrode material

The invention discloses a preparation method of a copper-silver doped lithium iron phosphate positive electrode material, and belongs to the technical field of preparation of lithium iron phosphate positive electrode materials. On the basis of an original positive electrode material, crystallization occurs when phase precipitation, in the crystallization process, a part of ferrous ions are subjected to isomorphous replacement by copper ions, a part of lithium ions are subjected to isomorphous replacement by silver ions, at the same time, under the action of potassium thiocyanate and sulfonated coal, the iron ions and the lithium ions leave original lattice positions and go into an organic phase, holes are generated in a crystal lattice, the positive electrode material with a lithium iron phosphate material as the priority and copper and silver materials as the auxiliary is prepared, and the purposes of improving ion activation performance and material electrical conductivity are achieved. The preparation method has the beneficial effects that the copper-silver doped lithium iron phosphate positive electrode material is fast in ion diffusion, good in activation performance, and high in tap density, has the tap density up to 1.7-2.4 g/mL; and the method is simple in preparation, the electrical conductivity is good, the low-temperature discharge performance is good, and the specific capacity reaches more than or equal to 190 mAh/g.