COMPOSITE LITHIUM MANGANESE IRON PHOSPHATE MATERIAL, PREPARATION METHOD THEREFOR, SECONDARY BATTERY AND ELECTRICAL DEVICE

This application provides a composite lithium manganese iron phosphate material and a preparation method thereof, a secondary battery, and an electric apparatus. The composite lithium manganese iron phosphate material includes lithium manganese iron phosphate particles and a coating layer. An upper service voltage of the lithium manganese iron phosphate particles is denoted as V1 in V; and the coating layer covers at least partial surface of the lithium manganese iron phosphate particles, the coating layer includes metal nanoparticles, an oxidation voltage of the metal nanoparticles is denoted as V2 in V, and the composite lithium manganese iron phosphate material satisfies V1