(363b) Tunable 3-D MnO2/Graphene Composites for Next-Generation High Energy Density Supercapacitors

Supercapacitors are promising electrochemical devices for energy storage.  Supercapacitors, with advantages of high power density, excellent cyclability, high efficiency and low fabrication cost, can find important applications in different areas, such as electric vehicles, industrial equipment, intermittent energy storage and electronic devices. However, current electric double-layer capacitors have low energy density, which restrict the even broader applications of supercapacitors. In the last decade, significant amount of effort has been invested on increasing the energy density of supercapacitors, specifically, the introduction of nanomaterials as electrode materials with large surface area and enhanced conductivity has achieved improvement. 

In this presentation, we will present our recent effort on the design and fabrication of a high-energy 3-D composite of 2-D graphene nano-sheets and 1-D MnO2 nano-wires where graphene nano-sheets provide high surface area, high conductivity as well as excellent mechanical support for high-capacitance MnO2. MnO2 serves as spacer to prevent graphene nano sheet from restacking and also provides pseudo capacitance to extent energy performance.

The 3-D composites were fabricated by facile hydrothermal method followed by modified Hummus method. The structure and composition of the 3-D composites can be easily tuned by adjusting the reaction time, temperature, concentration of precursors.  The size, morphology and crystallization of MnO2 nanowires and the mass ratio between MnO2 and graphene were optimized to achieve highly improved electrochemical performance, which demonstrated the potential applications of the 3-D composite for next-generation high-energy density supercapacitors. Three electrodes and two electrodes set up were employed to test electrochemical performance of the as prepared 3-D MnO2 and graphene composites and consistent results were obtained.