Graphene papers have great potential for various applications, such as electrodes in energy storage devices, protective coating, and desalination, because of their free-standing structure, flexibility, and chemical tunability. The inner structures of the graphene papers can affect their physical properties and device performance. Here, we investigated a way to fabricate graphene papers from crumpled reduced graphene oxide (rGO) spheres. We found that ultrasonication was useful for tailoring the morphology of the crumpled graphene spheres, resulting in a successful fabrication of graphene papers with tunable inner pore structures. The fabricated graphene papers showed changes in mechanical and electrical properties depending on their pore structures. In addition, the tailored pore structures had an influence on the electrochemical performance of supercapacitors with the fabricated graphene papers as electrode materials. This work demonstrates a facile method to fabricate graphene papers from crumpled rGO powders, as well as a fundamental understanding of the effect of the inner pore structures in mechanical, electrical, and electrochemical characteristics of graphene papers.
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/cm 2 at a current density of 0.8 mA/cm 2 with a PVA/LiCl gel electrolyte. This corresponds to areal energy and power densities of 5.04 μWh/ cm 2 and 0.50 mW/cm 2 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.
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