Electrochemical characteristics of a new electric double layer capacitor with acidic polymer hydrogel electrolyte

The article presents the results of a study on activated carbon fiber cloth (AC) and a hydrophobic microporous polypropylene (PP) membrane, both chemically modified with acidic acetone aldol condensation products, and on testing their use as an electrode material and separator in electric double layer capacitors (EDLCs). Polymer hydrogel used was based on poly(acrylamide) (PAAM), H2SO4 and water. Electrochemical characteristics of EDLCs were investigated by cyclic voltammetry and galvanostatic charge-discharge cycle tests and also by impedance spectroscopy. As a result, the capacitor with polymer hydrogel was found to exhibit similar capacitance as that with the H2SO4 aqueous solution and an excellent high-rate dischargeability. At the 4000th cycle of potential cycling (0.5 A g−1) the specific capacitance of 132 F g−1 was obtained with a energy density of 3.45 Wh kg−1 at a power density of 56 W kg−1. The above results provide valuable information to explore the novel composition of EDLCs.