Preparation method of high-safety high-capacity lithium manganese iron phosphate

A preparation method of lithium manganese iron phosphate, comprising the following steps:

• S1:
• mixing an iron source, a phosphorous source and an antioxidant into a solution, introducing nitrogen into the solution to serve as a protective gas to prevent oxidization, and synthesizing a ferrous phosphate precursor through a co-precipitation process, sintering the obtained ferrous phosphate precursor, and then removing all crystallized water to obtain an anhydrous ferrous phosphate precursor;
• S2;
• mixing a manganese source, a phosphorous source and an antioxidant into a solution, introducing nitrogen into the solution to serve as a protective gas to prevent oxidization, and synthesizing a manganese phosphate precursor through the co-precipitation process, and sintering the obtained phosphorous source to obtain an anhydrous manganese phosphate precursor;
• S3:
• adding lithium phosphate and deionized water into the anhydrous ferrous phosphate precursor obtained in step S1, and performing ball milling and wet sanding to obtain slurry A;
• S4;
• adding lithium phosphate, an organic carbon source, a dispersant, a dopant and deionized water into the anhydrous manganese phosphate precursor obtained in step S2, and performing ball milling and wet sanding to obtain slurry B;
• and
• S5;
• mixing the slurry A obtained in step S3 with the slurry B obtained in step S4 and performing ball milling, spray drying, sintering and air jet pulverization to obtain high-safety high-capacity lithium manganese iron phosphate.