Electrochemical Characterization of Cleaning Nickel Foam Current Collector for Supercapacitor Application

Abstract

AbstractCleaning nickel (Ni) foam substrate is essential in removing any contamination and changing the surface morphology of a substrate. In this study, Ni foam substrates were cleaned via sonication in different concentrations of HCl acid solution. The samples were also characterized by electrochemical analysis, such as cyclic voltammetry, galvanostatic charge–discharge, and electrochemical impedance spectroscopy. Cleaning of Ni foam substrate with a 2.5 M HCl acid solution showed an oxide layer with the uniform thickness (0.034 μm) of coating before detachment took place. The cycling behavior of Ni foam substrate cleaned with a 2.5 M HCl acid solution responded with supercapacitor characteristics such as redox peaks with a small potential difference (0.398 V at a scan rate of 10 mV s−1) and has the highest diffusion coefficient values for anodic (6.55 × 10−6 cm2 s−1) and cathodic (6.44 × 10−6 cm2 s − 1) peaks. The performance of Ni foam cleaned with a 2.5 M HCl acid solution also showed the highest areal discharge capacity (1758.2 F cm−2 at a current density of 8 mA cm−2). The effect in the electrochemical effect was supported by the impedance analysis. This finding indicates that the suitable concentration for Ni foam cleaning should be less than a 2.5 M HCl acid solution to avoid the detachment of the oxide layer.KeywordsSupercapacitorNickel foamCleaningRedox reactionCyclic voltammetry