High-performance asymmetric supercapacitor based on graphene hydrogel-nickel composite and manganese (II) oxide-nickel hybrid

Supercapacitors have emerged with the potential to enable major advances in energy storage. Literatures have shown that they have a number of important features including fast charging/discharging rate, excellent cycle stability, long shelf live and are environmentally friendly. As a result, supercapacitors may become an attractive power solution for an increasing number of applications. In this report, the performance of a type of supercapacitor, hydrid (asymmetric) capacitor will be evaluated. In theory by utilizing two different composite materials in each electrode, namely the Graphene Hydrogel - Nickel Foam (GH-NF) as the negative electrode and Manganese Dioxide-Nickel Foam ( MnO2-NF) as the positive electrode, the hybrid supercapacitor with an asymmetric electrode configuration will be able capitalise on both electrode materials' advantages in improving overall cell voltage, energy and power densities. Various electrochemical tests such as Cyclic Voltammetry (CV), Galvanostatic Charge-Discharge (GCD) techniques and characterisation test such as field emission scanning electron microscopy (FESEM) have been used to evaluate their performance. The asymmetric supecapacitor could cycle reversibly in a voltage of 0-2.0 V and gives an energy and power densities of 16.06kWh/kg and 2kW/kg respectively. Moreover, the asymmetric supercapacitor exhibit excellent cycle stability, and the capacitance retention of the asymmetrical supercapacitor is 81% after repeating the GCD test at a constant rate of 2A/g for 5000 cycles.Bachelor of Engineering (Chemical and Biomolecular Engineering