Enhanced ionic conductivity of PEO-based solid electrolyte through synergistic dissociation effect

Abstract

Low ionic conductivity is an obstacle to realize the commercial application of PEO-based solid polymer electrolyte due to high crystallinity and poor segment motion of PEO. Herein, a kind of Co-based metal-organic framework (Co-MOF) is synthesized as the filler to inhibit PEO crystallization and produce a synergistic dissociation effect between LiTFSI and PEO so as to improve the ionic conductivity. The Lewis acid-base pairs formed between metal Co2+ and TFSI− facilitates the dissociation of LiTFSI. While the nitro group of the organic framework drags the ether unit of PEO, releases Li+ and improves Li+ hopping. The ionic conductivity of PEO/Co-MOF-5% reaches 1.26×10−4 S cm−1 and a reversible capacity of 111 mAh g−1 is obtained for Li|(PEO/Co-MOF-5%)|LiFePO4 cell after 120 cycles at room temperature.