Fabricating high-performance symmetric coin cell supercapacitor using MnO2/CuO/Co3O4 decorated on rGO sheets as electrode material

Abstract

Supercapacitors show great potential as energy storage devices and could be the ideal choice for enhancing electronic systems. Here the synthesized rGO, MnO2, CuO and Co3O4 were interlaced via the hot-injection method to produce the rGO/MnO2/CuO/Co3O4 (RMCC). Various structural, functional, thermal, morphological and electrochemical characterizations of this nanocomposite RMCC were analyzed. In both 3-electrode and 2-electrode systems, electrochemical experiments were conducted using electrolytes of various pH levels to find out their specific capacitance, energy and power density and the most beneficial electrolyte that could be used for the fabrication of the coin cell supercapacitor was selected. A specific capacitance of 932.358 F g−1 was established, giving rise to an energy density of 204.49 W h kg−1 and highest power density of 2.5 kW kg−1. The cyclic stability of 85.12 % was obtained after 5000 continuous charge-discharge cycles under KOH. The material was then developed into a coin cell supercapacitor, which had the areal specific capacitance, energy and power density of 133.41 F cm−2, 41.67 μW h cm−2 and 0.996 mW cm−2, respectively. Two such coin cells were mounted onto a holder which glowed a red LED for 2.5 days after it was charged.