POSITIVE ELECTRODE ACTIVE MATERIAL AND PREPARATION METHOD THEREOF, POSITIVE ELECTRODE PLATE, LITHIUM-ION SECONDARY BATTERY, AND BATTERY MODULE, BATTERY PACK, AND APPARATUS CONTAINING SUCH LITHIUM-ION SECONDARY BATTERY CROSS-REFERENCE TO RELATED APPLICATIONS

A positive electrode active material and a preparation method thereof, a positive electrode plate, a lithium-ion secondary battery, and a battery module, battery pack, and apparatus containing such lithium-ion secondary battery are provided. The positive electrode active material includes matrix particles and a coating layer covering an exterior surface of the matrix particle, where the matrix particle includes a lithium nickel cobalt manganese oxide, and the coating layer includes an oxide of element M; the matrix particle is doped with element Mand element M, element Min the matrix particle is uniformly distributed, and element Min the matrix particle has a decreasing concentration from the exterior surface to a core of the matrix particle; and element Mand element Mare each independently selected from one or more of Mg, Al, Ca, Ba, Ti, Zr, Zn, and B, and element Mincludes one or more of Si, Ti, Cr, Mo, V, Ge, Se, Zr, Nb, Ru, Rh, Pd, Sb, Te, Ce, and W.