Effect of temperature on the hybrid supercapacitor based on NiO and activated carbon with alkaline polymer gel electrolyte

A hybrid supercapacitor was fabricated with NiO and activated carbon as positive and negative electrode, PVA-KOH-H2O containing 5 M KOH as alkaline polymer gel electrolyte, respectively Cyclic voltammetry, electrochemical impedance spectroscopy and galvanostatic chargedischarge measurements were applied to investigate the dependence of the hybrid supercapacitor on the temperatures from -20 to 40 degrees C. The results demonstrated that the capacitive performance of the hybrid supercapacitor turned even better with the temperatures rising up from -20 to 40 degrees C. The increase of temperature improved the conductivity of the alkaline polymer gel electrolyte, decreased the charge-transfer resistance and made the better contact at the interface between the electroactive materials and the alkaline gel electrolyte at higher operating temperature. The maximum of the specific capacitance and energy density of the hybrid supercapacitor were 73.4 F/g and 26.1 Wh/kg at the current density of 0.1 A/g and the operating temperature of 40 degrees C, respectively. (c) 2006 Elsevier B.V All rights reserved.