Ion exchange membranes as electrolyte for high performance Li-ion batteries

High ionic conductivity exceeding 10(-3) S cm(-1) at room temperature is achieved with lithiated perfluorinated sulfonic acid (PFSA-Li) ion exchange membranes by swelling in nonaqueous organic solvents. The dependence of ionic conductivity on the membrane equivalent weight, solvent uptake, solvent properties including viscosity and dielectric constant and temperature is investigated for PFSA-Li membranes. The high performance of Li-ion battery using the PFSA-Li membranes as both electrolyte and separator is demonstrated. This new battery shows very good thermal stability and cyclic performance as compared to conventional Li-ion battery using organic liquid electrolytes. At 55 degrees C, this battery shows less than 3% discharge capacity loss over 120 cycles, however battery with liquid electrolyte decreased to 76% of the initial capacity after 80 cycles.