Highly mesoporous carbons derived from corn silks as high performance electrode materials of supercapacitors and zinc ion capacitors

An agricultural waste, corn silks, is used as raw material to prepare mesoporous carbons for electrochemical energy storage applications. The natural hollow tubular structure of corn silks leads to adequate mixing of the KOH activating reagent with the carbon precursor and results in highly mesoporous carbons. When tested as active materials of both electrical double layer capacitors (EDLCs) and zinc ion capacitors (ZICs), the mesoporous carbons exhibit very encouraging energy storage properties. The EDLC cell using 1 M TEABF4/PC (propylene carbonate) electrolyte delivers an energy density of 25 Wh kg−1 even at a high power density of 23,070 W kg−1, while the ZIC cell with 1 M Zn(CF3SO3)2/DMF (N, N-Dimethylformamide) electrolyte displays a high specific energy of 38.5 Wh kg−1 at 14,741 W kg−1. The high specific surface area and large mesopore volume of the corn silks-derived mesoporous carbons might have provided more adsorption sites for the formation of electrical double layer and also facilitated the ion diffusion kinetics, which have synergistically improved the energy-power outputs in both EDLCs and Zn-ion capacitors.