Synthesis of copolymers of N‐vinylpyrrolidone and 2‐ethylhexyl acrylate by DL‐methionine‐mediated reversible deactivation radical polymerization and their dispersion behavior in preparation of LiFePO₄ battery positive slurry with high solid content

Abstract

Dispersants play a significant role in the formulation of positive battery slurry. Adding a small amount of dispersant can effectively reduce the viscosity of the slurry, which is beneficial for the production of positive batteries. A series of copolymers of N‐vinylpyrrolidone (NVP) and 2‐ethylhexyl acrylate (2‐EHA) with different molar ratios of NVP to 2‐EHA, different polymer molecular weights and different polymer structures are synthesized by dl‐methionine‐mediated reversible deactivation radical polymerization. The ability of these copolymers to disperse LiFePO4 battery positive slurry with a high solid content (57.08%) as dispersants has been evaluated. Research shows that when the ratio of NVP to 2‐EHA is 20 and the polymer molecular weight is 6000, poly(N‐vinylpyrrolidone‐ran‐2‐ethylhexyl acrylate) (NVP‐ran‐2‐EHA) exhibits the strongest dispersing ability to the slurry. This polymer can reduce the viscosity of the slurry by 43.925% and has the longest stabilization time of 3 h, which is better than poly(N‐vinylpyrrolidone) (PVP) and poly(N‐vinylpyrrolidone)‐block‐poly(2‐ethylhexyl acrylate) (PVP‐b‐PEHA) with the same molecular weight.