Effect of dealloying the redox-active zinc-based electrodes on the performance of asymmetric supercapacitors

Abstract

One of the challenging problems to solve in the design of high-performance supercapacitors (SCs) is converting the surface of the electrodes to porous nature. Therefore, this study is aimed to increase the surface area of the NiZn electrodes by using a fast and low-cost technique which is based on alloying/dealloying the metals. Nickel/Zinc (NiZn) alloy was obtained by depositing Zn electrochemically on porous Ni foam. Later, by using the galvanostatic scanning technique, Zn was dealloyed and the surface area was further enlarged. Electrochemical properties of alloyed and dealloyed NiZn electrodes were first evaluated as half-cell configuration in 6 M potassium hydroxide (KOH) solution with respect to Pt electrode. Then, two different asymmetric SCs, Cu-NiZn(alloyed) and Cu-NiZn (dealloyed) were constructed and characterized as the two-electrode configurations in the same electrolyte. Cyclic voltammetry at different scan rates from 5 to 200 mV/s and galvanostatic charge-discharge techniques at different current densities varying from 2 to 50 A/g were used to carry out the capacitive properties of the SCs. It was clearly observed that dealloying the electrode results in increasing electrochemical performance as expected where the maximum energy and power densities increased to 12.2 Wh/kg and 30.4 kW/kg, respectively.