Binder free cobalt Manganese layered double hydroxide anode conjugated with bioderived rGO cathode for sustainable, high-performance asymmetric supercapacitors

Abstract

Metal-organic frameworks (MOFs) possessmultifunctional characteristicssuch as tuneable pore structure and high specific surface area and are being designed with great interest to enhance the electrochemical properties of current energy storage devices. In this aspect, MOFs-derived layered double hydroxides (LDHs) are important candidates for advanced supercapacitors due to their high electrochemical activity and electric conductivity. Herein, we report synthesis of Cobalt Manganese layered double hydroxides (CoMn LDH) utilising Co MOF as a precursor via ion exchange method, while optimising the dosage of Mn to achieve the best possible structural outcome. The unique structure of CoMn LDH expressed high electrochemical parameters possessing specific capacitance of 1305F/g at 1 A/g. Afterwards, an asymmetric supercapacitor device was fabricated employing CoMn LDH as cathode and coffee grounds derived rGO (reduced graphene oxide) as anode. The as-prepared asymmetric supercapacitor device demonstrated a maximum working potential window of 1.2 V with energy and power density of 23.8 Wh/kg and 0.30 kW/Kg respectively. The device also exhibits superiorcoulombic efficiency and capacitance retention of 71.11 % and 82.7 % respectively over 3010 charge–discharge cycles that represents an effectiveapproach towards sustainable and effectiveenergy storage devices. In a nutshell, our study centred on adjusting composition, engineering structures, and assembling devices.