High-frequency carbon supercapacitors from polyfurfuryl alcohol

Porous carbons with controllable and narrow pore-size distributions are prepared from the chemical activation of polyfurfuryl alcohol (PFA). High apparent BET surface areas, up to 2600 m2 g−1 (2611 m2 g−1 by Density Functional Theory (DFT)), and good electrical conductivities (up to ∼130 S cm−1) are obtained. By varying the potassium hydroxide: carbon precursor ratio, the preparation of carbons with different proportions of micro- and fine mesoporosity (<5 nm) can be tailored to provide an ideal electronic and ionic pore structure for electrochemical energy-storage devices, such as electrical double-layer capacitors. High specific capacitance values are obtained up to 147 F g−1 in a voltage window of 2.5 V using 1 M tetraethyl ammonium tetrafluoroborate in acetonitrile. Moreover, excellent high-current and high-frequency performance is demonstrated: 100 F g−1 at 225 A g−1 (10 Hz) and ∼30 F g−1 at 100 Hz. When comparing the performance with commercial activated carbons (ACs) of similar textural properties, the PFA-derived ACs demonstrated better performance in terms of higher capacitance values and improved rate capabilities. There is a 125% increase in capacitance values at 1 kHz.

► The PFA derived carbons exhibited high capacitance values of up to 147 F g−1 in 1 M tetraethylamonium tetrafluroborate in acetonitrile at 2.5 V.
► Outstanding rate capability was observed; with capacitance values of up to 100 F g−1 obtained at a very high currentdensity of 225 A g−1.
► PFA-derived carbons provided 25% greater capacitance at 1 Hz than conventional activated carbons and a 125% greater capacitance at a frequency of 10 Hz.
► At 100 Hz, the PFA carbons could deliver >30 F g−1, making these materials very promising for the fabrication of high frequency supercapacitors.