Graphene/tungsten disulfide core-sheath fibers: High-performance electrodes for flexible all-solid-state fiber-shaped supercapacitors

Highlights: • A rGOF@WS₂ core-sheath fiber was synthesized via a one-step hydrothermal method. • The flexible fiber-shaped supercapacitor with rGOF@WS₂ core-sheath electrodes has high capacitance and energy. • The high performance is due to the unique core-sheath structure and synergistic effects of graphene and WS₂. -- Abstract: Fiber-shaped supercapacitors are an essential component for making wearable electronics and smart textiles. Despite the significant progress in this area, it is still a challenge to develop large capacitance, high energy density fiber-shaped supercapacitors for energy storage applications. Herein, we report a unique core-sheath fiber comprising graphene core and radially-aligned tungsten disulfide sheath via a one-step hydrothermal method. Two such fibers were used as electrodes for making an all solid fiber-shaped supercapacitor. This device has an areal capacitance as large as 270.36 mF cm⁻² and volumetric capacitance as high as 54.07 F cm⁻³ (energy density 16.86 μWh cm⁻²). The graphene core ensures the fiber to have high conductivity, while the sheath nanosheet array creates numerous active sites and enables fast ion diffusion. The electrode material with a high capacitance, long-term stability, and excellent flexibility may form a novel candidate for the development of high-performance energy storage fibers.