Hierarchically structured MnO2/graphene/carbon fiber and porous graphene hydrogel wrapped copper wire for fiber-based flexible all-solid-state asymmetric supercapacitors

Abstract

Recent progress in fiber-based supercapacitors has attracted tremendous attention due to the tiny volume, high flexibility and weavability of the fibers, which are required for the development of high-performance fiber electrodes. In this work, we report for the first time, the design and fabrication of two types of core–shell fiber-based electrodes, i.e. hierarchically structured manganese dioxide (MnO₂)/graphene/carbon fiber (CF) and three-dimensional (3D) porous graphene hydrogel (GH) wrapped copper wire (CW), and their practical application in a fiber-architectured flexible all-solid-state supercapacitor. Taking advantage of the synergistic effects of the different components in the hierarchically structured nanohybrid fiber electrodes and the merits of the proposed synthesis strategies, the assembled asymmetric supercapacitor device using MnO₂/graphene/CF as the positive electrode and GH/CW as the negative electrode could be cycled reversibly in a high-voltage region of 0–1.6 V, delivering a high areal energy density of 18.1 μW h cm⁻² and volumetric energy density of 0.9 mW h cm⁻³. Furthermore, our fiber-based flexible supercapacitor also shows a good rate capability, excellent flexibility and high long term cyclability, which makes it a promising power source for flexible energy-related devices.