Deposition of spinel cobalt nickel on nickel foam by a constant current electrochemical method and its supercapacitor application

A facile synthesis of novel flower-like NiCo2O4 was developed based on an electrochemical method and subsequent calcination method. The synthesis involved the co-electrodeposition of a bimetallic (Ni,‏Co) hydroxide precursor on a Ni foam support and subsequent thermal transformation to spinel mesoporous NiCo2O4. The coating was evaluated using scanning electron microscopy, X-ray photoelectron spectroscopy (XPS) and electrochemical cyclic voltammetric (CV) test. The smart combination of NiCo2O4 nanostructures and Ni foam showed a promising synergistic effect or capacitors with greatly enhanced performance. The porous foam and NiCo2O4 can provide a large surface area and accelerated the diffusion of the active species. According to XPS results, The combination of cobalt and nickel anions in NiCo2O4 afforded binary redox couples of Co2+/Co3+ and Ni2+/Ni3+ that will largely enhance the capacitive properties. This novel material exhibited a high specific capacitance of 2196 F/g at a scan rate of 5mV/s within a -3/0 mA/cm2 current density. The CV curve confirmed the pseudocapacitor behavior of the electrode. The good electrochemical performances suggested that these unique hierarchical (SEM results) NiCo2O4 could be promising materials for energy and environmentally related applications.