Negative electrode active material, process for preparing the same, and secondary battery, battery module, battery pack and apparatus related to the same

A process for preparing a negative electrode active material, comprising the following steps:

• (1) dissolving a polymer precursor in a solvent, and stirring until uniform dispersion, to obtain a solution of the polymer precursor;
• (2) adding a core material into the solution of the polymer precursor, and stirring, to obtain a mixed slurry, wherein the core material is one or more selected from the group consisting of a silicon-based negative electrode material and a tin-based negative electrode material;
• (3) drying the mixed slurry in an inert non-oxidizing gas atmosphere, to obtain a solid powder;
• and
• (4) mixing the solid powder with a sulfur powder to obtain a mixture, and subjecting the mixture to heat-treatment under an inert non-oxidizing gas atmosphere, to obtain the negative electrode active material;
• wherein the negative electrode active material comprises the core material and a polymer-modified coating layer on at least part of a surface of the core material, the polymer-modified coating layer comprises sulfur element and carbon element, the sulfur element has a mass percentage of from 0.2% to 4% in the negative electrode active material, the carbon element has a mass percentage of from 0.5% to 4% in the negative electrode active material, the polymer-modified coating layer comprises —S—C— bond, and the polymer-modified coating layer further comprises —S—S— bond.