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Enhancing the Rate Capability of Hybrid Supercapacitors Based on Redox Active Electrolytes through High-Surface Area Reduced Graphene Oxide
To alleviate the drawbacks of hybrid supercapacitors based on redox active electrolytes, we have developed an asymmetric system, in which a nanoporous activated carbon electrode is substituted by high-surface-area reduced graphene oxide (rGO). Importantly, rGO with surface area about 1000 m2 g-1 is made by a simple process route not involving any activation step.
Using high-surface-area rGO has led to a dramatic improvement in the rate capability of hybrid devices whereas the high surface area of rGO provided for effective charge balance. The high conductivity of rGO has allowed cycling hybrid cells up to a high current density of 6.5 A/g (considering the total active mass of both electrodes) without any significant capacitance fading. Significant energy improvements can further be expected by exploring different redox active electrolytes and graphene materials with even higher specific surface area.