A single step strategy to fabricate graphene fibres via electrochemical exfoliation for micro-supercapacitor applications

A green and low-cost method is presented to fabricate graphene fibre electrodes by electrochemical exfoliation of thin strips of graphite foil. When assembled into micro-supercapacitors, the graphene fibres achieved an excellent electrochemical capacitance (∼247.6 mF cm−2 at ∼2 mA cm−2) and low equivalent series resistance (∼2.4 Ω), a significant improvement over the typically used graphene oxide based fibres. This excellent capacitive performance indicates these graphene-based energy storage devices could be ideal for microelectronics applications. Additionally, an all-solid-state flexible micro-supercapacitor was fabricated using a gel electrolyte (H3PO4/PVA) and exhibited a high areal capacitance of 70.6 mF cm−2 and a superior cycling stability of ∼96% capacitance retention after 2400 cycles, suggesting possible applications for flexible energy storage. The easily scalable and facile single step strategy presented here outperforms the conventionally used graphene oxide based methods, which typically require harmful chemicals and involve a more complex synthesis procedure.