Lithium-ion secondary battery, battery apparatus, power consuming apparatus, method for preparing positive electrode active material, and method for preparing positive electrode plate

A lithium-ion secondary battery, comprising:

• a positive electrode plate, a negative electrode plate, and an electrolyte, wherein
• the positive electrode plate comprises a positive electrode current collector and a positive electrode film layer disposed on at least one side of the positive electrode current collector;
• the positive electrode film layer comprises a positive electrode active material, and the positive electrode active material comprises lithium-containing transition metal phosphate particles whose surfaces are at least partially provided with a carbon coating material;
• in a cross section of the positive electrode film layer in a thickness direction of the electrode plate, an area proportion of particles having a particle size of 1 μm to 5 μm is 30.0% to 50.0%, an area proportion of particles having a particle size of 50 nm to 200 nm is 3.0% to 15.0%, wherein the particles are analyzed in a scanning electron microscope (SEM) image of the cross section, an area of each of the particles is represented by a pixel area of the particle, the area proportion of particles having a particle size of 1 μm to 5 μm is a ratio of a sum of the areas of the particles having the particle size of 1 μm to 5 μm to a sum of the areas of all counted particles, the area proportion of particles having a particle size of 50 nm to 200 nm is a ratio of a sum of the areas of the particles having the particle size of 50 nm to 200 nm to a sum of the areas of all counted particles;
• and
• a mass proportion of a magnetic material in the positive electrode film layer is greater than or equal to 20 ppm and less than or equal to 1980 ppm.