Supercapacitors on hairs with quantum capacitance-dominant extraordinary capacitance

Graphene-based planar microsupercapacitors are promising energy storage devices for microelectromechanical systems. However, the capacitance and energy density of such graphene-based microsupercapacitors cannot achieve further promotion because of the lack of strategies that permit tailoring both chemical and geometric structures of graphene at the nanoscale. In this study, supercapacitors on hairs with quantum capacitance-dominant extraordinary capacitance are found. Simulations reveal that the record high capacitance and energy density are attributed to the enhanced quantum capacitance effect. The graphene electrodes are prepared by femtosecond laser direct writing-assisted reduction and N-doping of graphene oxides on the human hair surface. Due to the distinct quantum capacitance dominance, the microsupercapacitors exhibit extremely high capacitance (∼3000 mF/cm 2 ) and energy density (∼417 μWh/cm 2 ). We hope that this work will promote the development of microsupercapacitors with high capacitance and energy density.