Thermoresistant Hybrid Ag/RGO Fiber Supercapacitors

Reduced graphene oxide (RGO) fiber micro-supercapacitors can potentially be used as flexible energy-storage devices. However, the low capacity for volumetric energy storage and poor strength of pure RGO fibers limit their application. Doping hybrid RGO fibers with a nanofiller is an effective approach to improving electrochemical performance, but the addition of nanoparticles to the graphene oxide spinning solution hampers spinning, thus reducing the mechanical strength of the fibers. Meanwhile, the hydrothermal method allows loading a limited number of nanoparticles or agglomerated nanoparticles on the fiber surface. In this study, we fabricated and deposited Ag nanoparticles on RGO fibers by gamma irradiation. This method effectively solved the agglomeration of nanoparticles during GO wet-spinning. The RGO fiber was further reduced by a gamma ray. The fiber supercapacitor assembled with Ag/RGO fibers had a superior specific volumetric capacity of 154.6 F/cm3 in a gel solid electrolyte consisting of (PVA/LiCl) and an extraordinary volumetric energy density of 21.47 mWh/cm3, which considerably exceeded the density of commercial lithium-ion flexible batteries (4 V/500 µAh); meanwhile, the fiber attained a 58 % increment in tensile strength and showed enhanced thermal stability after grafting of Ag nanoparticles. Moreover, the Ag/RGO fiber supercapacitor possessed a long cyclic life without a significant reduction after 5000 cycles.