Lithium-containing multi-phosphate cathode material, preparation method therefor, and secondary battery

A lithium-containing multi-phosphate cathode material, comprising a single-core multi-shell lithium manganese iron phosphate composite material, wherein

• the single-core multi-shell lithium manganese iron phosphate composite material comprises:
• a core made of lithium iron phosphate or lithium manganese iron phosphate,
• N lithium manganese iron phosphate coating layers coated on an outer surface of the core, and
• a carbon coating layer coated on an outermost layer of the single-core multi-shell lithium manganese iron phosphate composite material;
• wherein N is an integer ranging from 6 to 10;
• wherein a manganese content in the N lithium manganese iron phosphate coating layers increases successively from an inside to an outside along a radial direction;
• wherein the lithium manganese iron phosphate coating layers include lithium manganese iron phosphate particles, and particle sizes of the lithium manganese iron phosphate particles in the N lithium manganese iron phosphate coating layers decrease successively from the inside to the outside along the radial direction;
• and
• wherein molar ratios of manganese element to iron element in the N lithium manganese iron phosphate coating layers are independently (1-9):(9-1).