Negative electrode active material regenerated from waste battery as well as regeneration method and application of negative electrode active material

The invention belongs to the field of battery material recovery, and particularly discloses a method for regenerating a negative electrode active material from a waste battery, which comprises the following steps: disassembling the waste battery to obtain a negative electrode plate, pre-modifying the negative electrode plate in an aqueous solution containing Fe < 3 + >, and then separating to obtain a waste negative electrode material; the method comprises the following steps: slurrying a waste negative electrode material and a boron-containing auxiliary agent by using an organic solvent, and sealing the obtained slurry in a pressure-resistant container for solvent heat treatment to obtain a treated material A; the treated material A, a salt auxiliary agent and M metal are mixed and subjected to heat treatment, a treated material B is obtained, the M metal is Mg and/or Al, and the salt auxiliary agent is salt which is not pyrolyzed at the heat treatment temperature; and carrying out acid treatment on the trea