A rational design of MnO2/CuO/r-GO hybrid and biomass-derived activated carbon for asymmetric supercapacitors

Abstract

Supercapacitors (SCs) are being considered the next-generation energy storage devices due to their outstanding energy density and exceptional cyclic stability. A solid-state symmetric supercapacitor (ASC) has been designed using ternary MnO2/CuO/rGO hybrid as the anode and lemon peel (LP) derived activated carbon (AC) as the cathode. The MnO2/CuO/r-GO hybrid was synthesized via a simple hydrothermal method. A ternary MnO2/CuO/r-GO hybrid showed the specific capacitance of 793.14 F g−1 at 1 A g−1 with the life cycling performance of 94% retention after 10,000 cycles at a high current density of 10 A g−1, owing to the synergistic effect of high conductive r-GO and high pseudocapacitive MnO2/CuO hybrid with high surface area (113.501 m2 g−1). The overall electrochemical performance of MnO2/CuO/r-GO hybrid electrode materials was improved when compared with pure MnO2 and MnO2/CuO electrode materials due to the combined effect of high specific capacitance MnO2 and CuO and high surface area and electrical conductivity of rGO. Moreover, the AC was derived from LP and studied its physics-chemical properties. The AC material exhibits a high specific capacitance of 206 F g−1at 1 A g−1 with outstanding capacitance retention of 96% even after 10,000 cycles. The assembled MnO2/CuO/r-GO//AC asymmetric supercapacitor (ASC) delivered a specific capacitance of 177 F g−1 at 2 A g−1 with a high energy density of 79.60 W h kg−1 at a power density of 2430 W kg−1 with the wide range of operating potential window (0–1.8 V). The ASC has exhibited excellent cycle stability with capacitance less than 10% after 10,000 cycles at 10 A g−1.