Hierarchical flower-like nanostructures of manganese–cobalt–copper nanoneedles for high performance symmetric supercapacitor

Hierarchical flower-like structures of nanoneedles of ternary metal oxides comprising of Manganese–Cobalt–Copper (MCC) are synthesized on nickel foam by a simple hydrothermal technique. The synthesis of MCC is done with varying concentrations of manganese and copper, and the products are studied using X-ray photoelectron spectroscopy, X-ray diffraction, and scanning electron microscopy. Electrochemical studies of MCC electrodes are performed using cyclic voltammetry, galvanostatic charge discharge and electrochemical impedance spectroscopy. Ternary metal oxide electrode demonstrates better electrochemical performance in comparison to mono and bimetallic oxide electrodes, which can be attributed to synergistic effects between the metals. Specific capacitance of 1607 F/g at scan rate 5 mV/s is shown by the best performing MCC electrode. The capacitance retention is 98.33% after 2800 charge-discharge cycles. Symmetric device fabricated by the MCC electrode delivers energy density of 37 W h/kg at a power density of 228 W/kg.