Proton conducting Gel Polymer Electrolytes for supercapacitor applications

•Gel polymer electrolytes with different solvents content have been proposed.•Electrochemical capacitors with proposed electrolytes have been assembled and tested.•The influence of solvents content to EC properties has been observed.•The capacitance change vs. temperature has been analyzed.

A non-aqueous, mechanically-stable, proton conducting gel polymer electrolyte has been prepared for Electrochemical Capacitor (supercapacitor) applications. It is based on 2-hydroxymethylmethacrylate monomer mixed with two different solvents (propylene carbonate and N,N-dimethylformamide). It was shown that the capacitive performance changes with the gel electrolyte composition. The proton conduction type mechanism affects ions mobility and transport into the porous carbon electrode. Addition of small amounts of DMF solvent leads to a change in the conduction mechanism from a vehicle- to a Grotthuss-type, and capacitance of 90 F g−1 at 20° C was achieved using a 15 wt. % DPhHPO4/P(HEMA)/30 wt. % DMF-70 wt. % PC gel composition. Electrochemical tests were done in a large temperature range (from −40 to 80 °C). The cell delivered a capacitance of 54 F g−1 at −40 °C, that is 60% of the value obtained at room temperature, and 90 F g−1 at 80 °C within voltage window of 1 V.