A Novel Method to Fabricate Nitrogen and Oxygen Co-Doped Flexible Cotton-Based Electrode for Wearable Supercapacitors

In this work, we prepared a nitrogen and oxygen co-doped flexible cotton-based carbon electrode with high electrochemical performance by using a simple dyeing and carbonization method for its potential application in wearable energy storage devices. The optimized dyed cotton-based electrode with 10 % o.w.f. (percentage on weigh of fabric) dyeing concentration shows a high areal specific capacitance of 1836 +/- 20 mF cm(-2) at 2 mA cm(-2) in aqueous 6 M KOH, superior cycling lifespan (99.1 % capacitance retention after 5000 cycles), good coulombic efficiency, and high rate property. The outstanding properties can be attributed to the synergistic effect between the double-layer capacitance (superior conductivity, large surface area, and good wetability) and the extra pseudocapacitance originating from N and O heteroatoms in the dye molecules. More importantly, the symmetric supercapacitor created with CDF-10 % electrodes exhibits a significant volumetric specific capacitance of 18.2 F cm(-3) and energy density of 5.7 mWh cm(-3) at a power density of 45.2 mW cm(-3), which can power an electronic clock for several minutes. The impressive resulting performance demonstrates that this inexpensive synthetic method, which can be scaled-up, can be used to create promising materials for wearable electronics.