Facile\nFabrication of Flexible Graphene-Based Micro-Supercapacitors\nwith Ultra-High Areal Performance

Abstract

Micro-supercapacitors\n(MSCs) with high performance and flexibility\ncould meet the demand of miniaturized electronic devices. The advantages\nof graphene and reduced graphene oxide (rGO), such as high specific\nsurface area, good conductivity, mechanical properties, and electrochemical\nstability, make them promising candidates for flexible electrodes\nof MSCs. However, the low mass loading and electrical double-layer\ncapacitor (EDLC) mechanism of graphene-based MSCs lead to a low areal\nelectrochemical performance, which is a key parameter of miniaturized\npower sources. Here, we demonstrate a high-loading (21.1 mg cm^–2) graphene-based MSC through hydrothermal, physical\npressing and laser-engraving methods. Impressively, the symmetrical\nMSC can exhibit an areal capacitance as high as 569.5 mF cm^–2. At the same time, the MSC exhibits an excellent areal energy density\nof 79.1 μWh cm^–2, which is superior performance\namong graphene-based MSCs reported in research studies. Meanwhile,\nthe MSC also demonstrates long-term cyclic stability (98.8% capacitance\nretention after 20 000 cycles) and robust flexibility (no attenuation\nof capacitance at bending angles from 0 to 180° and 98.4% capacitance\nretention after 2000 bending cycles). Therefore, this work offers\na facile method to greatly promote the areal electrochemical performance\nof graphene-based MSCs, which are promising in broader applications.