Development of gel polymer electrolyte based on LiTFSI and EMIMFSI for application in rechargeable lithium metal battery with GO-LFP and NCA cathodes

Abstract

In this paper, we report the effect of ionic liquid 1-ethyl-3-methylimidazolium bis(fluorosulfonyl)imide (EMIMFSI) on polymer poly(ethylene oxide) (PEO) and salt lithium bis(trifluoromethylsulfonyl)imide (LiTFSI) electrolyte system. The glass transition temperature and degree of crystallinity decreased with an increasing amount of EMIMFSI resulting in an increase in the ionic conductivity. The highest room temperature ionic conductivity and Li+ transference number are observed for PEO + 20 wt% LiTFSI + 10 wt% EMIMFSI. These prepared gel polymer electrolytes (GPEs) are thermally and electrochemically stable enough for battery application. Two different cells with graphene oxide-doped lithium iron phosphate, LiFePO4 (GO-LFP) and lithium nickel cobalt aluminum oxide, LiNi0.80Co0.15Al0.05O2 (NCA) cathodes were tested with prepared GPEs. GO-LFP showed more predictable and consistent nature of capacity fading and good discharge capacity. However, NCA showed higher discharge capacity, better cyclic performance, lower capacity fading, and better performance at high C rates. © 2019, Springer-Verlag GmbH Germany, part of Springer Nature.