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Increased working voltage of hexamine-coated porous carbon for supercapacitors

Candelaria, Stephanie L., Cao, Guozhong
Science bulletin 2015 v.60 pp. 1587-1597
capacitance, carbon, chemical composition, chemical structure, electric power, electrolytes, energy density, sol-gel processing, surface area
Highly porous carbon, both unmodified and hexamine-coated on the pore surfaces, is tested at high working voltages in organic electrolyte for supercapacitors in order to enhance the energy density and power density. Sol–gel processing allows for excellent control of the porous structure and chemical composition of carbon, resulting in a material with high surface area and a low level of impurities. This porous carbon can be modified using a simple solution-based method to enhance capacitance. Increasing the working voltage from 2.0 to 3.0V significantly improves performance for both unmodified and hexamine-coated carbon. The energy density and power density increase at higher working voltage, and under certain conditions, the capacitance increases as well. Cyclic stability is also investigated, with hexamine-coated carbon retaining more of its initial capacitance than unmodified carbon at all working voltages.