Composites of poly (vinylidene fluoride-co-hexafluoropropylene) (PVDF-co-HFP) and room temperature ionic liquid 1-methyl-1-butylpyrrolidinium bis (trifluoromethanesulfonimide)(BMPy-TFSI) with 0.5 m Lithium bis (trifluoromethanesulfonimide) salt (LiTFSI) incorporating hollow silica spheres (HS, ~20 nm) were fabricated. Thus, the prepared solid composite polymer electrolytes (SCPEs) exhibit an unprecedented ionic conductivity of 4.92x10-4 S.cm-1 at room temperature that can be explained because of the formation of a nanodomain of ionic liquids by HS. Incorporation of HS not only increased the ionic conductivity but also increased thermal and electrochemical stability and mechanical strength compared with SCPEs without HS. High oxidation stability of 4.5 V vs Li/Li+ and higher interfacial stability towards lithium metal are the remarkable achievements of SCPEs. Lithium metal batteries (LMBs) with LiFePO4 as cathode and SCPEs as electrolytes cycled at current rate 1 C at 60°C and 0.5 C at room temperature showed a highly stable discharge capacity of 155.0 mAh/g (after 450 cycles) and 120.0 mAh/g (after 120 cycles) respectively with a coulombic efficiency of 99.9 %. Higher Li-ion conductivity and stable electrochemical performance with high thermal and electrochemical stability, lower interfacial resistance, and superior mechanical strength are the key aspects of SCPEs that will pave the way to commercialize the solid state LMBs.

Novel composite polymer electrolytes with superior ionic conductivity with nanodomain of ILs in polymer matrix for highly reversible solid-state Lithium Metal Batteries (LMBs)

2019 Spring National Meeting

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