ZnCl2-assisted conversion of nitrogen-containing biomass carbon from marigold flower: Toward highly porous activated nitrogen-doped carbon for low ESR and enhanced energy density supercapacitors

Herein, we report the synthesis and characterization of hierarchical porous activated nitrogen-doped carbon from pyrolysis of dried marigold flower precursor as an effect of different impregnation zinc chloride (ZnCl2) (1:1, 1:3 and 1:5) named FZ11, FZ13, and FZ15. BET and FESEM show the enhancement in porosity and surface area with activation with highest specific surface area of 1274.45m(2)/g for FZ15. XPS confirms the engineering of nitrogen content into functional nitrogen doped sites upon the action of ZnCl2 activation as N-reservoir which results in increase in specific capacitance of fabricated symmetric cell (without any conductive black) increases with activation and shows the highest specific capacitance of 179 F/g, energy density of 23 Wh/kg and power density of 556 W/kg for FZ15 sample. Addition of carbon black helps in lowering ESR to 0.77 Omega and enhancement in energy density and series combination of 3 such cells glow yellow LED for similar to 3 min.

Automated summary

Hierarchical porous activated nitrogen-doped carbon was synthesized from pyrolysis of dried marigold flower precursor, and the effect of different impregnation zinc chloride (ZnCl2) ratios (1:1, 1:3 and 1:5) on the material properties was investigated. The activation process with ZnCl2 increased the porosity and surface area of the material, resulting in higher specific capacitance in fabricated symmetric cells. The addition of carbon black reduced the equivalent series resistance (ESR) and improved the energy density, allowing for the series combination of three cells to power a yellow LED for approximately 3 minutes.