Preparation and electrochemical characteristics of metal oxides based electrodes for supercapacitor

Abstract

In recent times, supercapacitors used to store electrical energy are quite attractive among different energy storage devices, owing to its salient features such as high-power density, quick charge/discharge, long cyclic operations, reasonable energy density, and clean and safe. In supercapacitors, energy storage is based on the reversible redox reactions and charge accumulation. There are three main types in supercapacitors based on the storage principles, namely Electric Double-Layer Capacitor (EDLC), pseudocapacitor, and a hybrid supercapacitor (the combination of EDLC and pseudocapacitor). newlineIn EDLC, there is no chemical reaction, volume change, and depletion of electrolytes and therefore, it could improve cyclability. Although it has some good features as said above, it is mainly suffered because of low specific capacitance and energy density. In a pseudocapacitor, it can achieve higher values of specific capacitance and energy density than EDLC. Transition metal oxides and conducting polymers are widely investigated as the electrode materials for pseudocapacitor applications. However, transition metal oxides are preferred over conducting polymers since conducting polymers are suffered due to poor cyclability. newlineFrom the group of transition metal oxides, extensive research works were carried out on ruthenium oxide, vanadium oxide, manganese oxide, and nickel oxide for supercapacitor applications. newline