N/S co-doped carbon nanosheets derived from sugarcane processing by-products for flexible solid-state supercapacitors

Developing sustainable carbon materials from biomass for supercapacitors is a promising solution to alleviate energy and environmental pressures. In this paper, novel N/S co-doped carbon nanosheets derived from sugarcane processing by-products are proposed. Flexible and binder-free electrodes based on carbon felt and sulfonated potassium fulvic acid were prepared by a simple impregnation-carbonization method. The maximum areal specific capacitance, power density and energy density of the symmetric supercapacitor are 409.9 mF cm −2 (1 mA cm −2 ), 0.92 mW cm −2 and 184.5 μWh cm −2 , respectively. The operating voltage of the device increases to 1.8 V by using LiCl electrolyte. After 10,000 cycles, the capacitance remains 90 % of its initial value. Besides, the device possesses good flexibility, which can be bent at different angles and has a capacitance retention of 92.3 % after 5000 bending cycles. The supercapacitor is of great significance for the recovery of crop processing by-products to prepare flexible electronic devices.