Multi-element cathode material, preparation method thereof, positive electrode plate, and lithium-ion battery

A multi-element cathode material, wherein the multi-element cathode material is composed of secondary particles agglomerated by primary particles, wherein:

• a ratio of a total cross-sectional area of the primary particles with more than 5 grain boundaries to a cross-sectional area of the secondary particles is greater than or equal to 0.75 and less than 1;
• a porosity on a cross-section of the secondary particles is more than 0% and less than or equal to 2%;
• and
• the grain boundaries are each a contour line of an interface, on the cross-section of the secondary particles, between the primary particles with the same structure but different orientations, and the grain boundaries have each a length greater than or equal to 0.1 μm;
• the cross-section of the secondary particles refers to a cross-section of particles obtained by ion milling with a cross-sectional diameter equal to an average particle size DB50 of the secondary particles.