Facile synthesis and high volumetric capacitance of holey graphene film for supercapacitor electrodes with optimizing preparation conditions

ABSTRACT For miniaturized portable energy storage devices with limited space, electrode materials are needed to be developed in the direction of reducing the occupied volume without compromising high specific capacitance and stable cycling ability. Herein, a facile strategy was developed to fabricate a free-standing binder-free holey graphene film as a supercapacitor electrode. In this material mechanism, holey structure in graphene sheets provides abundant ion transport channels and accelerates ion diffusion efficiency, which could guarantee that this film performs a high packing density without compromising electrochemical performance. After being properly optimized on the amount of H2O2 added and the mechanical pressure while preparing, this electrode film could consequently perform a high volumetric capacitance of 406 F cm−3 and excellent cycle stability with a packing density of 1.34 g cm−3. Therefore, this kind of densely packed electrode film with excellent electrochemical performance is of great significance for the development of miniaturized portable energy storage devices.