Surface-engineered flexible fibrous supercapacitor electrode for improved electrochemical performance

Electronic textiles consisting of flexible and smart fibers have the potential to provide an intelligent platform for significantly expanding the future scope of wearable electronic applications. Thus, the integration of wearable electrochemical energy storage systems into the flexible platform is a key feature for efficiently powering and operating these future electronic textiles during bending, knotting, folding, and rolling. The present paper describes a flexible smart fibrous supercapacitor consisting of surface-engineered carbon fibers functioning as both the electrode and the current collector. In addition, the gel-electrolyte is used for an ion transfer and an electrode separation. The developed supercapacitor exhibits a robust energy storage performance superior to that of previously-reported fiber-based supercapacitors, with a high energy density of 3.5–2.0 μWh cm⁻² and a power density ranging from 4 to 30 μW cm⁻². These results are strongly attributed to the oxygen-containing functional groups on the carbon surface that provide the pseudocapacitive redox reaction and improved wettability. Furthermore, the fabricated supercapacitor shows outstanding mechanical flexibility and excellent thermal stability with minor capacitance degradation, thus demonstrating its promising applicability to electronic textiles.