Electrochemical, structural and thermal studies of poly (ethyl methacrylate) (PEMA)-based ion conductor for electrochemical double-layer capacitor application

Solid polymer electrolyte based on poly (ethyl methacrylate) (PEMA) and lithium bis(trifluoromethanesulfonyl) imide (LiTFSI) was prepared for electrochemical double-layer capacitor (EDLC) application. Incorporation of 50 wt% LiTFSI elevated the ionic conductivity by five orders of magnitude from (4.64 ± 0.01) × 10 –11 to (1.22 ± 0.01) × 10 –6 S cm −1 . The doping of LiTFSI also improved the thermal stability of the polymer electrolyte from 331 to 384 ºC. Moreover, structural information from FTIR suggested that Li + can interact with oxygen of carbonyl and ester groups of PEMA. Linear sweep voltammetry (LSV) showed that there is an improvement on the electrochemical stability window from 2.2 to 3.2 V upon addition of 40 and 50 wt% of LiTFSI. Transference number analysis affirmed that ion is the major contributor to the ionic conductivity of the PEMA-LiTFSI polymer electrolyte system. The fabricated PEMA-LiTFSI-based EDLC cell exhibited specific capacitance of 358.1 m F g −1 . The energy density and power density of the PEMA-LiTFSI-based EDLC cell were 22.2 mWh kg −1 and 14.0 W kg −1 , respectively.