POSITIVE ELECTRODE ACTIVE MATERIAL, PREPARATION METHOD THEREFOR AND POSITIVE ELECTRODE PLATE CONTAINING SAME, AND SECONDARY BATTERY AND ELECTRIC APPARATUS

The present application provides a positive electrode active material, a method for the preparation thereof and a positive electrode plate, a secondary battery and an electrical device containing the same. The positive electrode active material having a core-shell structure, comprising a core and a shell covering the core, wherein the core has a chemical formula of LiaAxMn1-yByP1-zCzO4-nDn, the shell comprises a first cladding layer covering the core, and a second cladding layer covering the first cladding layer, wherein the first cladding layer comprises pyrophosphate MP2O7 and phosphate XPO4, and the second cladding layer comprises carbon. The positive electrode active material of the present application enables the secondary battery and electrical device to have a relatively high energy density, and good cycling performance, rate performance and safety performance.