Preparation and Characteristics of Lithium Battery Separator Based on Cellulose Modification by Water-Soluble Polyimide Impregnated

Abstract

In order to improve the comprehensive performance of lithium battery separator, cellulose based on lithium battery separator (mCNS) was prepared by cellulose/nylon 6 with ionic liquid [Emim]Ac as solvent and enhanced with polyimide (PI) as the impregnated solution. The properties of modified separator were investigated. As could be discovered from the experimental results that the addition of PI endowed the separators with more uniform and dense micro-pores, and the ions can pass through better, which was conducive to improving the electrical conductivity of the separator. Remarkable tensile strength (69 MPa) and elongation at break (35.3%) can be obtained at PI concentration of 40%. Meanwhile, the electrolyte absorption and retention rate reached 238.7% and 69.4%. The value of maximum thermo-shrinkage stress was 1.38 N and the thermo-shrinkage rate could reach 1.5%, which guaranteed the thermal stability of the battery. The electrochemical voltage was attained to 4.7 V and the ionic conductivity was improved to 0.61×10−3 S⋅cm−1. The mCNS separator preparation process was simple and the performance was excellent, which provides a novel idea for the green development of lithium battery separator.