Electrochemical co-deposition of metal oxide/graphene nanocomposites for micro-supercapacitor

Abstract

Micro-supercapacitors (MSCs) have gained significant attention in both academia and industry due to their excellent cycling stability, high power density, and long lifespan. They are widely used in miniaturized electrochemical energy storage devices and hold great potential for applications in portable electronics, wireless sensors, and other related fields. Efforts have been made to simplify the fabrication techniques of MSCs from the synthesis of electrode materials, electrode structure design, to the deposition process. However, there still lacks of a cost-effective and reliable manufacturing process to combine the multiple fabrication steps into a single operation. Hereby, this thesis work proposes an electrochemical co-deposition approach to make graphene and metal oxide nanocomposites layer in a single step to achieve high performance MSCs. Selective cathodic deposition was used to coat graphene-wrapped MnO2 and Fe2O3 nanoparticles on target MSCs patterns. Various parameters, including the output signal, coating time, and concentration of metal salt precursor were examined to verify the optimal deposition condition. SEM, Raman, and XPS analyses were used to characterize the resulting hybrid materials. Additionally, the relative electrochemical performance of the MSCs devices with either liquid or solid electrolytes were evaluated. The result of this study offer an alternative approach for the one-step fabrication of graphene-related nanocomposites, specifically designed for miniaturized supercapacitors application.