Facile fabrication of mesoporous carbon from mixed polymer precursor of PVDF and PTFE for high-power supercapacitors

Abstract

Highly porous activated carbon is an essential electrode material for high-energy-density super-capacitors, since the electrical charge is stored through electrolyte-ion adsorption on an electrode with high surface area. Here, we report the facile and simple synthesis of an activated carbon with tailored porosity from the blended polymers with different thermal stabilities, i.e., polyvinylidene fluoride (PVDF) and polytetrafluoroethylene (PTFE). Through a thermal treatment (900 degrees C) under inert atmosphere, PVDF is simply transformed into highly microporous (<2 nm) carbon, owing to the release of the combined hydrogen and fluoride. The microporous surface morphology reduces the specific capacitance at high discharging rates. Meanwhile, the PTFE is completely evaporated to the C2F4 gas at 900 degrees C under an inert environment. The mixed polymer with a specific ratio (PVDF:PTFE = 2:1) is carbonized to porous carbon with a highly accessible surface area. The mesopore (2-50 nm) formed via C2F4-gas escape from PTFE facilitates ionic transfer to the surface at a rapid discharging rate with the high specific capacitance, i.e., 99 F g(-1). Compared with the PVDF-alone derived carbon, the carbon derived from the appropriately mixed precursors exhibits a 19 % higher specific capacitance and increased capacity retention at a 10-fold faster discharging rate.