Synthesis, analysis and characterization of nitrogen/sulfur co-doped activated carbon for high-performance all-printed flexible supercapacitor

Achieving more effective nitrogen/sulfur (N/S) co-doping activated carbon (AC) with superior specific surface area and pseudocapacitive properties remains challenging. Herein, a simple hydrogen peroxide preprocessing of commercial AC has been demonstrated to dramatically promote the co-doping of N/S into AC. The N/S co-doped AC with hydrogen peroxide preprocessing (N/S-HAC) exhibits >2-fold increase in specific capacitance and exceptional rate capability (70 % capacitance retention from 0.5 A g(-1) to 100 A g(-1)) relative to the pristine commercial AC. Systematic experiments and characterizations reveal the significantly enhanced capacitive performances of N/S-HAC can be attributed to the etching-induced pore expansion and high-concentration N/S co-doping incorporated pseudocapacitance. Furthermore, an all-printed N/S-HAC based flexible supercapacitor is fabricated by a facile screen-printing technique and shows an outstanding areal capacitance of 100 mF cm(-2), energy and power density of 0.027 mWh cm(-2) and 28 mW cm(-2), respectively, as well as ultrahigh stability (90 % capacitance retention after 20,000 cycles at 10 mA cm(-2)). These results are superior to most of carbon-based flexible supercapacitors and even better than some pseudocapacitive materials. In addition, the printed flexible supercapacitor maintains stable capacitance after 1000 bending cycles, even when bent to different angles (45 degrees, 90 degrees, 135 degrees, and 180 degrees), indicating the excellent flexibility. Additionally, the packaged flexible supercapacitor arrays integrating multiple supercapacitors solidly light up LEDs, even during dynamic bending. This work opens a promising prospect for the development of carbon-based flexible supercapacitors with both outstanding power and energy density, remarkable stability, and excellent flexibility.