Negative pole piece additive, negative pole slurry, negative pole piece and related device

The invention relates to a negative pole piece additive, negative pole slurry, a negative pole piece and a related device. The negative pole piece additive comprises a core part and a shell part, wherein the core part comprises alkali metal salt and/or alkaline earth metal salt; and the shell part coats at least part of the surface of the core part, the shell part comprises a swelling polymer, and the swelling degree of the swelling polymer is greater than or equal to 110%. The cycle performance of the battery monomer can be improved.