Activated Carbon–Aluminum Oxide Composite Material on Nickel Foam as Supercapacitor Electrode in KOH Electrolyte

A composite material based on activated carbon–alumina is investigated as an electrode for supercapacitor devices. The effects of surface morphology and chemical composition of the carbon‐based materials on the electrochemical properties are studied by using multiple techniques including cyclic voltammetry, galvanostatic cycling, and electrochemical impedance spectroscopy. For the pristine activated carbon electrode, the specific capacitance exhibited by the symmetric supercapacitor is 11 F g −1 at a current density of 0.1 A g −1 , for an operating voltage of 0.6 V. However, the supercapacitor composed of the composite electrodes presents an obvious enhancement of the specific capacitance up to 161 F g −1 at 0.1 A g −1 and operates over a larger cell voltage of 1.6 V. For the composite activated carbon–aluminum oxide device, the exhibited specific energy and power are equal to 57.52 Wh kg −1 and 3200 W kg −1 , respectively, at an applied current density of 0.1 A g −1 . The specific capacitance exhibited by the device assembled with activated carbon–aluminum oxide electrodes is ≈14 times higher than that delivered by the device assembled with pristine activated carbon electrodes. Moreover, the activated carbon–aluminum oxide device could maintain up to 87% of its initial capacitance after 2000 voltammetric cycles.