Lithium Iron Manganese Phosphate Cathode Material, Preparation Method and Application Thereof

A preparation method of a lithium iron manganese phosphate cathode material, wherein the lithium iron manganese phosphate cathode material comprises a lithium iron manganese phosphate substrate and a coating layer on a surface of the lithium iron manganese phosphate substrate;

• the coating layer comprises carbon quantum dots containing amino groups;
• and a mass ratio of manganese ions to carbon quantum dots containing amino groups is (4.5˜5.5):1 in the lithium iron manganese phosphate cathode material, the preparation method comprising following steps:
• Step one:
• Mixing the lithium iron manganese phosphate substrate with chitosan in a liquid phase;
• adding the carbon quantum dots containing amino groups simultaneously;
• and spray-drying to obtain coated lithium iron manganese phosphate powder;
• and
• Step two:
• Drying and grinding the coated lithium iron manganese phosphate powder to obtain an organic polymer-coated lithium iron manganese phosphate precursor;
• heating up and cooling down the organic polymer-coated lithium iron manganese phosphate precursor to obtain a cathode material of lithium iron manganese phosphate powder coated with carbon quantum dots.