Negative electrode active material, method for preparing same, secondary battery and apparatus including the secondary battery

A method for preparing a negative electrode active material comprising a core and a coating layer covering a surface of the core, comprising the following steps:

• a) providing a coke raw material, wherein the coke raw material has a volume average particle size Dv50 of from 6 μm to 12 μm, and the coke raw material has a volatile content C1 satisfying 1% ≤C1≤12%;
• b) shaping and grading the coke raw material to obtain a precursor, wherein the precursor has a particle size uniformity U1 satisfying 0.2≤U1≤0.5;
• c) granulating the precursor, during which a binder is added in an amount of C2, wherein C1, C2 and U1 satisfy 21% ≤(C1+C2)/U1×100%≤50%;
• d) graphitizing the granulated product at a temperature of from 2800° C. to 3200° C. to obtain an artificial graphite, wherein the artificial graphite has a particle size uniformity U2 satisfying 0.22≤U2≤0.48;
• and
• e) coating the artificial graphite with an organic carbon source, performing heat treatment to form an amorphous carbon coating layer on at least a part of the surface of the artificial graphite, to obtain the negative electrode active material, wherein the organic carbon source added during forming the coating layer has an amount C3, and wherein C3, C1, C2 and U2 satisfy 20% ≤(C1+C2+C3)/U2×100%≤55%, and 1.5% ≤C3×carbon residue rate ≤2.5%,
• wherein the core comprises artificial graphite, the coating layer comprises amorphous carbon, and the negative electrode active material has a particle size uniformity of from 0.25 to 0.45.