Solid polymer electrolyte supported by porous polymer membrane for all-solid-state lithium batteries

Abstract

Solid polymer electrolytes composed of poly(ε-caprolactone) (PCL) and lithium bis(trifluoromethane) sulfonylimide (LiTFSI) salt were prepared for investigating their electrochemical properties. The optimized solid polymer electrolyte showed ionic conductivities of 2.5 × 10−5 and 1.6 × 10−4 S cm−1 at room temperature and 55 °C, respectively. Dimensional stability was improved by infiltrating PCL-based solid polymer electrolyte into the porous polymer membranes prepared from poly(ether imide) (PEI), polyacrylonitrile (PAN) and non-woven polypropylene (PP) membranes. Due to the highly porous nature and good compatibility of the PEI membrane toward the PCL-based solid polymer electrolyte, a solid-state Li/LiNi0.6Co0.2Mn0.2O2 cell assembled with a solid polymer electrolyte employing a PEI membrane exhibited the best cycling performance. Based on our results, this highly porous PEI membrane is proposed as a promising supporting membrane for enhancing the mechanical stability of amorphous solid polymer electrolytes for applications in all-solid-state lithium batteries.