Activated carbon (AC) fiber cloths and hydrophobic microporous polypropylene (PP) membrane, both
modified by plasma-induced graft polymerization of acrylic acid (AAc) under UV irradiation, and filled
with saturated lithium hydroxide solution were used as electrodes, a separator and electrolyte in electric
double layer capacitors (EDLCs). The modification process changed the hydrophobic character of AC and
PP materials to hydrophilic, made them wettable and serviceable as components of an electrochemical
capacitor. The presence of poly(acrylic acid) on the AC and PP surface was confirmed by SEM and XPS
methods. Electrochemical characteristics of EDLCs were investigated by cyclic voltammetry and galvanostatic
charge–discharge cycle tests and also by impedance spectroscopy. At the 1000th cycle of potential
cycling (1 A g−1) the specific capacitance of 110 F g−1 was obtained with a specific energy of 11Wh kg−1
at power density of 1 kW kg−1. The above results provide valuable information which may be used when
developing novel compositions of EDLCs.