Graphene Fibers Containing Activated Graphene for High-Performance Solid-State Flexible Supercapacitors

Fiber supercapacitors (FSCs) can be used to power future flexible devices such as wearable electronics and smart textiles. Here, highly porous activated graphene (AG) is embedded into graphene fibers to enhance the electrochemical performance of FSCs based on electric double-layer capacitance (EDLC). Wet spinning of AG mixed with graphene oxide (GO) and subsequent chemical reduction of GO to reduced graphene oxide (rGO) enable the fabrication of continuous and conductive graphene fibers. The AG powders with an extremely high surface area significantly improve the electrochemical performance of the FSCs. In particular, the rGO/AG fiber with an rGO/AG mass ratio of 80/20 achieves a specific areal capacitance of 145.1 mF/cm2 at a current density of 0.8 mA/cm2 with a PVA/LiCl gel electrolyte. This corresponds to areal energy and power densities of 5.04 μWh/cm2 and 0.50 mW/cm2 for the FSCs, respectively. Furthermore, flexible FSCs using the rGO/AG fibers demonstrate decent cycling capability, with a capacitance retention of 91.5% after 10 000 cycles. This work shows significant potential in fabricating AG-based fibers for developing high-performance flexible FSCs.