Wool textile-derived nitrogen-doped porous carbon cloth for a binder-free electrode material for high-performance flexible solid-state supercapacitors

With the rapid development of portable electronics and wearable devices, flexible solid-state supercapacitor (SC) has recently stimulated wide research interest. Herein, we one-step prepared a nitrogen-doped porous carbon cloth material by directly carbonizing a biomass wool textile without any chemical or physical activation. The obtained wool-derived nitrogen-doped porous carbon cloth (WNPCC) has a microporous structure with a high specific surface area of ~ 500 m 2 g −1 , as well as superior mechanical property that can be arbitrarily folded. As an electrode material without adding conductive agent and binder, greatly improved electrochemical performance is achieved by the WNPCC in comparison with the commercial carbon cloth and reported flexible SC electrodes. The area specific capacitance of the optimized WNPCC in three-electrode tests is 1012 mF cm −2 (1 mA cm −2 ), and meanwhile, an excellent durability at 90° bent state is proved. The PVA/H 2 SO 4 -based SC shows energy density of 76.6 µWh cm −2 at a power density of 0.60 mW cm −2 and retains 55 µWh cm −2 even at a high power density of 6.73 mW cm −2 with a wide voltage window of 1.4 V. More importantly, the specific capacitance value does not evidently decline when bending the SC device to various degrees in 2000 runs. This work provides a facile route to prepare flexible electrode material using sustainable biomass precursor, which not only is directly used as electrode for all-solid-state SCs, but also can act as the flexible conductive supporter for battery or electrocatalysis applications. Graphic abstract