A novel ionic liquid polymer electrolyte for quasi-solid state lithium air batteries

By Bai, Junjie; Lu, Huimin; Cao, Yuan; Li, Xudong; Wang, Junren
Published in RSC Adv. 2017

Abstract

Novel ionic liquid polymer electrolytes based on polymer poly(vinylidene fluoride-co-hexafluoropropylene) (PVdF-HFP), lithium bis(tri-fluoromethanesulfonyl)imide (LiTFSI) with different 1-ethyl-3-methyl-imidazolium bis(trifluoromethanesulfonyl)imide (EMITFSI) weight ratios have been synthesized and applied to quasi-solid state Li-air batteries. The morphology, electrochemical properties of prepared electrolytes, the discharge-charge capacity and cycling performance of the quasi-solid state Li-air batteries have been characterized and are discussed. Electrochemical properties of polymer electrolyte with incorporation of EMITFSI improved the electrochemical stability window (4.9 V) with higher ionic conductivity ([similar]4.30 [times] 10-3 S cm-1), but decreased the cationic transference number. The improvements are attributed to the reducing crystallinity of polymer matrix and formation of many homogeneous, large-size across-linked pores (60% EMITFSI), which could facilitate the transmission of Li ions. While for the quasi-solid state Li-air batteries, the ionic liquid polymer electrolyte shows good compatibility and safety with an Li anode and an air breathing cathode, significantly improved galvanostatic discharge-charge capacity and cyclic stability (without capacity fading until 20 cycles) in the capacity-controlled mode, which demonstrates that the novel ionic liquid polymer electrolyte is a potential choice for the quasi-solid state Li-air batteries for future practical applications.

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