Binder and preparation method thereof, negative electrode and preparation method thereof, and lithium ion battery

The invention belongs to the field of batteries, and particularly relates to a binder and a preparation method thereof, a negative electrode and a preparation method thereof, and a lithium ion battery. The binder is an aqueous solution of PAA-Li, and the pH value of the binder is 3.5-5.5. In the invention, the PAA-Li solution is adjusted to 3.5-5.5,-Li neutralized by a substituted-COOH group can stretch PAA molecular chains through electrostatic repulsive force between adjacent-COOLi under high pH, so that the crosslinking degree of the PAA molecular chains is not enough, and the cohesiveness is reduced, and after the pH is reduced, the crosslinking between the PAA molecular chains can be improved, and the cohesive force is further improved. 本发明属于电池领域，具体涉及一种粘结剂及其制备方法、负极及其制备方法、锂离子电池。粘结剂为PAA-Li的水溶液，pH为3.5～5.5。本发明中，将PAA-Li溶液调节至3.5～5.5，在高pH下，取代-COOH基团中和的-Li可以通过相邻的-COOLi之间的静电排斥力拉伸PAA分子链，导致PAA分子链的交联程度不够，以至于粘结性降低，而降低pH后可以改善PAA分子链之间的交联，进而提高粘结力。