Bimetallic nickel-cobalt nanospheres electrodeposited on nickel foam as a battery-type electrode material for fabrication of asymmetric supercapacitors

Abstract

The development of electrode materials with nanostructures is of great importance in the field of supercapacitors. In the present research, the direct simultaneous deposition of Ni-Co nanosphere (Ni-Co NS) on nickel foam as a substrate has been performed by facile one-step electrodeposition method without any template to provide excellent electrical conductivity and efficiency of electrode materials. The SEM images of Ni-Co NS electrode showed a nanosphere shape. The electrochemical performance of the electrodeposited nanosphere has been investigated by cyclic voltammetry, galvanostatic charge-discharge, and electrochemical impedance spectroscopy in 3 M KOH aqueous electrolyte. The Ni-Co NS electrode showed a good specific capacity of 564.6 C g−1 at 2 A g−1 with rate capability of 70% in the current density range of 2–20 A g−1, reasonable cyclic stability of 86% after 5000 cycles at the scan rate of 70 mV s−1, low internal resistance, and high surface area of the nanospheres. Interestingly, an asymmetric supercapacitor fabricated using Ni-Co NS and activated carbon as the positive and negative electrodes, respectively, operating at the potential window of 1.5 V delivered high energy and power densities of 34.5 Wh kg−1 and 683 W kg−1, respectively.