Study on preparation and properties of polyimide lithium battery separator

Abstract

Soluble polyimide was synthesized from 4, 4’-(4, 4’-Isopropylidenediphenyl-1, 1’-diyldioxy) dianiline (BAPP), 4, 4’-Diaminodiphenyl ether (ODA) and 4, 4’-Oxydiphthalic anhydride (ODPA) in a certain proportion. The porous polyimide (PI) membranes were prepared by phase transfer method. The molecular structure, pore size, contact angle and thermal stability were characterized by fourier transform infrared spectroscopy (FTIR), scanning electron microscope (SEM), contact angle measuring instrument. The results show that the prepared porous polyimide membranes have three-dimensional network of microporous structure with a surface pore diameter of 0.5-1 μm; The porosity increases with the increasing quality ratio of anhydrous ethanol and acetone in the solution, which reaches more than twice of the conventional Celgard 2400 membrane;The contact angles of the porous polyimide membranes are smaller than that of separator of the Celgard 2400 membrane and showing better lyophilicity, which were all take distilled water as the test solution. The porous polyimide membranes have better heat resistance, and the size does not change significantly after heat treatment at a maximum of 180°C for 0.5 h.