POSITIVE ELECTRODE ACTIVE MATERIAL, POSITIVE ELECTRODE PLATE, LITHIUM-ION SECONDARY BATTERY, AND APPARATUS

The present application discloses a positive electrode active material, a positive electrode plate, a lithium-ion secondary battery, and an apparatus. The positive electrode active material satisfies a chemical formula Li(NiCoMn)MOA, wherein M is one or more selected from Zr, Sr, B, Ti, Mg, Sn and Al, A is one or more selected from S, N, F, Cl, Br and I, −0.01≤x≤0.2, 0.12≤b/c≤0.9, 0.002≤b×c/a≤0.23, a+b+c=1, 0≤d≤0.1, and 0≤y≤0.2; and an interval particle size distribution curve of the positive electrode active material has a full width at half maximum Dof from 4 μm to 8 μm. The positive electrode active material provided in the present application has relatively low cobalt content and relatively high cycle life and capacity performance.