Cathode material and preparation method thereof and secondary lithium battery

A secondary lithium battery, comprising a cathode material represented by a chemical formula of LibNi1-x-yCoxAlyMzO2, where 0.95≤b≤1.10, 0≤x≤0.15, 0.01≤y≤0.1, 0<z≤0.05, and an M element is a metal element;

• the M element is distributed in interior and surface of the cathode material, the M element distributed in the interior of the cathode material is presented in a doped form, and the M element distributed in the surface of the cathode material is presented in a form of a coating layer formed of at least one of M oxide or lithium-M composite oxide, wherein when performing element line scan by a high-precision electron spectrometer along an approximate diameter direction in a cross-section of a particle of the cathode material cut by an ion beam cutter, the surface is defined as at an end of the diameter of the line analysis, and the interior is defined as at a center of the diameter;
• a molar ratio of the M element in the interior to the M element in the surface is greater than 0.5 and less than 1.5.

A cathode material, wherein a chemical formula of the cathode material is LibNi1-x-yCoxAlyMzO2, where 0.95≤b≤1.10, 0≤x≤0.15, 0.01≤y≤0.1, 0<z≤0.05, and an M element is a metal element;

• the M element is distributed in interior and surface of the cathode material, the M element distributed in the interior of the cathode material is presented in a doped form, and the M element distributed in the surface of the cathode material is presented in a form of a coating layer formed of at least one of M oxide or lithium-M composite oxide;
• a molar ratio of the M element in the interior to the M element in the surface is greater than 0.5 and less than 1.5.