Embodiments of this application provide a positive
electrode active material and a preparation method thereof, a positive
electrode plate, a secondary battery, a battery module, a
battery pack, and an electric apparatus. The positive
electrode active material includes a core and a shell layer enveloping the core, the core having a
chemical formula LiaAxMn1-yByP1-zCzO4-nDn, where A includes one or more elements selected from Zn, Al, Na, K, Mg, Nb, Mo, and W, B includes one or more elements selected from Ti, V, Zr, Fe, Ni, Mg, Co, Ga, Sn, Sb, Nb, and Ge, C includes one or more elements selected from B, S, Si, and N, and D includes one or more elements selected from S, F, Cl, and Br; and the shell layer is a
doped carbon layer, a
doping element in the
doped carbon layer including any one or more selected from
nitrogen,
phosphorus,
sulfur,
boron, and
fluorine. The rate performance and
cycling performance of a
lithium manganese phosphate positive electrode active material are improved.