The Effect of Different Mixed Organic Solvents on the Properties of p(OPal-MMA) Gel Electrolyte Membrane for Lithium Ion Batteries

A solvent is a key factor during polymer membrane preparation, and it is directly related to application performance as a separator for lithium ion battery (LIB). In this study, different mixed solvents were employed to prepare polymer (p(OPal-MMA)) membranes by the phase inversion technique. The polymer membrane then absorbed liquid electrolytes to obtain gel electrolytes (GPEs). The surface morphologies and porosities of these membranes were investigated, and lithium ion transferences and electrochemical performances of these GPEs were also measured. The membrane displayed an interconnected three-dimensional framework structure with uniformly distributed pores when using DMF as a porogen. When combined with acetone as the component solvent, the prepared GPE displayed the largest lithium ion transference number (0.706), the highest porosity (42.6%) and ion conductivity (3.99 × 10−3 S/cm). Even when assembled as Li/GPE/LiFePO4 cell, it exhibited the highest initial specific capacity of 167 mAh/g and retained most capacity (162 mAh/g) after 50 cycles. The results presented here probably provide reference for choosing an appropriate mixed solvent in fabricating polymer membranes.