Positive electrode active material and preparation method thereof, positive electrode plate, lithium-ion secondary battery, and battery module, battery pack, and apparatus related thereto

A lithium-ion battery, comprising a positive electrode plate, a negative electrode plate, a separator disposed between the positive electrode plate and the negative electrode plate, and an electrolyte, wherein the positive electrode plate comprises a positive electrode active material, the positive electrode active material is made by a process comprising:

• dividing a precursor of a doping element into L parts and used for doping in L batches, wherein L is 2 to 5;
• mixing a precursor of the positive electrode active material, a lithium source, and a first batch of the L batches of the precursor of the doping element to obtain a first mixture, wherein the precursor of the positive electrode active material is one or more selected from an oxide, a hydroxide, or a carbonate, the precursor of the positive electrode active material comprises Ni;
• performing a first sintering treatment of the mixture in an oxygen-containing atmosphere at a temperature of 600° C. to 1000° C.;
• mixing a product of the first sintering treatment with a second batch of the L batches of the precursor of the doping element to obtain a second mixture;
• performing a second sintering treatment of the second mixture in an oxygen-containing atmosphere at a temperature of 600° C. to 1000° C.;
• repeating until a product of an (L−1)th sintering treatment is mixed with an Lth batch of precursor of the doping element;
• and
• performing an Lth sintering treatment in an oxygen-containing atmosphere at a temperature of 600° C. to 1000° C. to obtain the positive electrode active material,
• wherein the positive electrode active material comprises secondary particles formed by agglomeration of primary particles, the primary particles comprise a lithium transition metal oxide, the lithium transition metal oxide comprises nickel and the doping element at a transition metal site,
• wherein a relative deviation (σ) of a local mass concentration of the doping element in the secondary particles is equal to or less than 16%,
• wherein a Young's modulus (E) of the primary particles satisfies 175 GPa≤E≤220 GPa,
• a true doping concentration (φ) of the positive electrode active material satisfies 3000 μg/cm3≤φ≤50000 μg/cm3.