Electrochemical properties of various NiO/activated carbon composites as supercapacitor electrode

Abstract

This research demonstrates that nickel oxide and activated carbon composite was synthesized from various resources and were applied supercapacitor electrode. Supercapacitors have garnered considerable attention over the past decades. Because they have high power density and long cycle ability compared to secondary batteries and conventional dielectric capacitors. Although various types of RuO2 with high capacitance have been studied among the pseudo-capacitors, they are limited to commercial products because of costliness and toxic nature. Therefore, we used nickel oxide instead of RuO2 as an electrode. Because, NiO have theoretically similar performance of RuO2 and economical availability. Composite of nickel oxide and activated carbon was synthesized through two step. The first step was that Ni(OH)2 was synthesized by precipitating method. After that, NiO was formed by calcination at $300^\circ C$ for 3 hours. The composites were analyzed by XRD, SEM, and EDX. It was confirmed that nickel oxide grew up on the surface of activated carbon. We investigated capacitance with various weight ratio of nickel oxide and activated carbon. We found that the highest specific capacitance was 624 F/g, 487 F/g, 403 F/g respectively at current density 1 A/g when nickel oxide:activated carbon is weight ratio of 1:20. Specific capacitance generally had tendency to increase with specific surface area in same composite. When compared to composite from microalgae and the others(wood, asphaltene), structural difference demonstrate in SEM image. BET surface properties also was confirmed for structural difference. Elemental analysis affected electrochemical properties of composites derived from various resources.