Lithium manganese iron phosphate material, preparation method therefor, positive electrode sheet and preparation method therefor and battery

A preparation method for a lithium manganese iron phosphate material, comprising:

• mixing a first raw material comprising a manganese source, an iron source, a complexing agent, a reducing agent and an alkaline solution to obtain a first reaction system, controlling a pH value of the first reaction system to be 9.0~11.0, and reacting each of components in the first reaction system to obtain a precursor FexMn(1-x)(OH)2, wherein 0<x<1;
• mixing a second raw material comprising the precursor FexMn(1-x)(OH)2, a lithium source, a phosphorus source, a dopant, and a carbon source to obtain a second reaction system, controlling a pH value of the second reaction system to be 8.0~9.5, performing spray-granulation of the second reaction system to obtain a sintering precursor, and performing a sintering treatment of the sintering precursor to obtain the lithium iron manganese phosphate having a structural formula of LifexMnyA(1-x-y)PO4, where 0<x<1, 0<y<1 0≤1−x−y≤0.2, and a dopant element A is selected from at least one of Be, Ca, Mg, Ba, and Sr.