Graphene-Based Fiber Shape Supercapacitors for Flexible Energy Storage Applications

Energy storage devices are essential because of ever-worsening fossil fuel depletion, increasing energy demand, and increasing environmental pollution. Maxwell Technologies, NessCap, Ashai Glass, and Panasonic commercialize carbon-based conventional supercapacitor devices. Carbon materials like graphene, carbon nanotubes, and activated carbon, are considered favourable materials for bendable and wearable electronic devices. The graphene, because of its high conductivity (thermal ~5 × 103 W m-1 K-1, electrical ~102 to 108 S m-1), extraordinary surface area (theoretically ~2630 m2 g-1), outstanding electrochemical performance (100 to 200 F g -1), less weight compared to transition metal oxides (because of less molecular weight of the carbon), outperform every other carbon material [1, 2]. The fiber-shaped supercapacitors are considered a potential future candidate for electrochemical energy storage systems and have gained considerable attention from the energy storage research community. This chapter discusses the importance of fiber-shaped supercapacitors, their evolution, various forms of their device structures, and electrolytes used for fiber-shaped supercapacitors. Further, the wet-spinning technique for synthesizing graphene fibers and their composites with pseudo-capacitive materials are also discussed.