N, O self-doped porous carbon derived from distiller's grains for high performance supercapacitors

Improving the charge storage capacity of carbon materials derived from biomass waste is an important aspect for their practical applications as supercapacitor electrodes. A reasonable design of heteroatom-doped carbon materials derived from industrial distiller 's grains can significantly enhance the efficacy of the supercapacitor. Therefore, a distiller's grain-derived (DG) N/O self-doped activated carbon (DG-5-X) was developed for use in supercapacitors. The incorporation of heteroatoms into porous carbon materials can facilitate enhanced electrode-to-electrolyte interaction resulting in improved pseudo-capacitance, thereby enhancing the electrochemical performance. A remarkable 345.2 F g−1 specific capacitance was demonstrated in a three-electrode system employing DG-5–6 (with N and O heteroatom contents of 1.62 % and 19.27 %, respectively) as the electrode in a 6 M KOH electrolyte solution (at 1 A g−1). In addition, a symmetric coin-type supercapacitor (SSC) device was developed, which demonstrated excellent cyclic stability and a competitive energy density of 12.2 Wh kg−1 (at a 348.8 W kg−1 power density). SSC retained 95.6 % of the capacitance after 5000 cycles at 5 A g−1. In summary, the distiller's grains as a raw material show great potential in the development of carbon-based energy storage materials that display outstanding electrochemical performance.