LITHIUM MANGANESE IRON PHOSPHATE COMPOSITE POSITIVE ELECTRODE MATERIAL, METHOD OF PREPARING THE SAME, POSITIVE ELECTRODE SHEET AND SECONDARY BATTERY

A lithium manganese iron phosphate composite positive electrode material, a method of preparing the same, a positive electrode sheet, and a secondary battery belonging to the technical field of battery active materials are provided. The lithium manganese iron phosphate composite positive electrode material includes a component A and a component B. The component A is a Ni/Ti co-doped lithium manganese iron phosphate material, and a chemical formula of the Ni/Ti co-doped lithium manganese iron phosphate material is LiMnFeNiTiPO, where 0≤x≤0.05 and 0≤y≤0.05. The component B includes amorphous carbon. The Ni+Ti co-doping strategy effectively addresses the problems such as energy density and capacity decay of the lithium manganese iron phosphate positive electrode material, so lithium manganese iron phosphate is enabled to better exert its advantages of high energy density, enhanced safety, and low costs, and the capacity and cycle stability of the lithium manganese iron phosphate battery are thus improved.