Flexible gel polymer electrolyte based on ionic liquid EMIMTFSI for rechargeable battery application

Abstract Development of high performance lithium polymer batteries (LPBs) with high thermal and electrochemical stabilities is now being intensively pursued for various applications like personal electronics, grid storage etc. In the present study, we report synthesis and characterization of a gel polymer electrolyte (GPE) based on polymer polyethylene oxide (PEO), salt lithium bis(trifluoromethylsulfonyl)imide (LiTFSI) and different amounts of added ionic liquid (IL) 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide (EMIMTFSI). Differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), complex impedance spectroscopy, ionic transference number studies, linear sweep voltammetry (LSV) and cyclic voltammetry (CV) studies exhibit promising characteristics of prepared GPEs for suitable application in LPBs. The GPEs show high thermal stability (i.e. no weight loss up to 310 °C), high ionic conductivity (∼2.08 × 10 −4  S cm −1 at 30 °C), high lithium transference number ( t Li +  = 0.39) and high electrochemical stability window (∼4.6 V). A low cost simple thermal lamination technique was used to encapsulate whole LPB assembly by sandwiching best performing GPE between a LiMn 2 O 4 cathode and lithium metal anode. In galvanostatic charge/discharge cycles the prepared cell showed good electrochemical performance.