| Abstract: | Capacitors based on structural carbon fiber electrodes and epoxy‐based gel polymer electrolyte have been fabricated. The electrochemical properties of electrolytes and capacitors were evaluated by linear sweep voltammetry, cyclic voltammetry (CV), galvanostatic charge–discharge, and electrochemical impedance spectroscopy techniques. Surface modification of carbon fibers was carried out by oxidation, and the structural and surface characteristics of carbon fibers were investigated by scanning electron microscope, Brunauer–Emmet–Teller, and Boehm titration. The results showed that the electrochemical stability window of the electrolyte reached 2.75 V and the ionic conductivity reached the order of 10−5 S/cm at room temperature. Surface modification of carbon fiber by oxidation can enlarge fiber area and strengthen fiber chemical activity, as well as its energy storage ability. The specific capacitance of epoxy/carbon fiber composite capacitor was obtained as high as 3.0 F/g with good cycling performance. POLYM. COMPOS., 36:1447–1453, 2015. © 2014 Society of Plastics Engineers |
