Nanostructured Co3O4 electrodes for supercapacitor applications from plasma spray technique

Abstract

► Nanostructured and porous Co 3 O 4 electrodes for supercapacitors. ► Flexible and binder free electrodes for high temperature supercapacitor applications. ► Electrodes developed, for the first time , by plasma spray process. ► Rapid processing of supercapacitors in a single step process using economical industrial scale technology. Among different transition metal oxides cobalt oxide (Co 3 O 4 ) has attracted considerable attention for supercapacitor applications because of its superior electrochemical characteristics at relatively low cost. Nanostructured Co 3 O 4 electrodes are usually prepared from powders using sol–gel and hydrothermal techniques, which require multi-step procedures and longer processing times. Here, we report synthesis and characterization of Co 3 O 4 supercapacitor electrode films deposited directly on current collectors via a single step solution precursor plasma spray route. In this approach, an aqueous solution containing cobalt acetate is axially fed into plasma plume to produce nanoparticulates of Co 3 O 4 via accelerated thermo-chemical conversion process, which are eventually deposited on a current collector substrate. Thus, developed Co 3 O 4 electrodes showed nano particulate structure with porosity. The phase structure and crystallinity of Co 3 O 4 electrode films were analyzed by X-ray diffraction and differential scanning calorimetry–thermogravimetry (DSC–TGA) studies. Electrochemical performance of these coatings showed a specific capacitance of ∼162 F g −1 with a retention capacity of 72.2% after 1000 cycles for a specific current rate of 2.75 A g −1 in 6 M KOH electrolyte.