Biomass-derived three-dimensional carbon framework for a flexible fibrous supercapacitor and its application as a wearable smart textile.

High electrochemical performance and mechanical reliability are two important properties of the flexible fibrous supercapacitors (FFSCs) used in portable and wearable electronics. Herein, we introduce high-performance and stable FFSCs produced using with a honeycomb-like structure (the key material) acting as a frame for an activated carbon (AC) coating. The honeycomb-like structure facilitates penetration of electrolytes and electron transport in the AC particles. This reduces the contact resistance between the AC and current collector, thereby enhancing the electrochemical energy storage. The FFSCs possess long length and area specific capacitances of 20.8 mF cm and 83.9 mF cm, respectively. In addition, the fabricated FFSCs display a maximum length (area) energy density of 3.98 μW h cm (16.1 μW h cm) at a power density of 0.07 mW cm (1.99 mW cm) and attain an excellent capacitance retention of 91% over 10 000 cycles. Moreover, the supercapacitors exhibit excellent mechanical flexibility with minor increase in capacitance upon bending. Three flexible fibrous supercapacitors in series power a red light-emitting diode, demonstrating the potential application of the flexible fibrous supercapacitors in smart textiles.