Holey graphene synthesized by electrochemical exfoliation for high-performance flexible microsupercapacitors

Abstract

As backup energy storage devices, flexible microsupercapacitors (MSC) are expected to play an important role in future self-powered microelectronics. Graphene-based MSCs have attracted substantial attention due to their power performance, excellent mechanical flexibility, and superb cycling stability. The enhancement of the electrochemical performance of graphene-based MSCs is crucial for their practical application but remains a challenge. Herein, we report an electrochemically exfoliated O, P-functionalized holey graphene (FHG) with a hierarchical porous structure for high-performance flexible MSC electrodes. The areal capacitance increases linearly with the thickness of the electrode owing to the high ion-accessible surface area as well as efficient electron and ion transport pathways. The as-fabricated FHG-MSC delivers an areal capacitance of 6.41 mF cm⁻², a volumetric capacitance of 30.51 F cm⁻³, and a high energy density of 4.24 mW h cm⁻³. Additionally, the MSC possesses exceptional mechanical flexibility with ∼99.7% capacitance retention over 500 bending cycles. Such outstanding results make it possible to use FHG in future high-performance self-powered microelectronics and provide a novel strategy for preparing few-layer functionalized holey graphene (FHG).