Fabrication and Performance Prediction of Graphene Microsupercapacitor Devices for Future Energy Storage Applications

Carley, Christopher Scott
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The state of our environment has necessitated a rapid increase in demand for renewable energy sources like solar, wind, etc. Unfortunately, these commonly available renewable energy sources have an implicitly intermittent nature of energy generation. Therefore, there is a need for fast charging high-capacity energy storage devices that can complement energy harvesting technologies. Compared to lithium-ion batteries and hydrogen fuel cells, supercapacitors exhibit superior power density (W/kg), enabling fast charging/discharging cycles, long life cycles, and a robust thermal operating range. However, supercapacitors have relatively low energy density (Wh/kg), which remains a significant challenge. This research presents a low-cost fabrication technique to produce all solid-state, flexible, and high-performance microsupercapacitor devices. The microsupercapacitors use solution-processable reduced graphene oxide (rGO) as their active material in an interdigitated electrode structure. Additionally, the experimental research efforts were guided by predictive power density and energy density performance models and simulations. Preliminary testing of the graphene microsupercapacitor devices proves the effectiveness of the newly outlined experimental procedure while investigating them as the next-generation high-performance energy storage device. Results indicate successful reduction from GO to rGO through Raman spectroscopy measuring a high D band to G band intensity ratio (ID/IG) of 1.65 and sheet resistance of 5.681 x 107 Ω/□. Additionally, the H3PO4/PVA gel electrolyte's relative permittivity was large, measuring around 9,000, the devices produced a capacitance in the nF range, low capacitance loss during flexing from 0-4%, and models predict devices exhibiting up to around a 30,000 W/kg power density and 8.5 Wh/kg energy density.

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Energy Density, Energy Storage, Graphene, Power Density, Reduced Graphene Oxide, Supercapacitor
Electrical and Computer Engineering