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

Abstract

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°, 90°, 135°, and 180°), 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.