Use of Surfactants for Continuous Operation of Aqueous Electrochemical Flow Capacitors

The electrochemical flow capacitor (EFC) is a novel design for supercapacitor technologies. To avoid misinterpretation arising from non-flow analytical methods, we have investigated an EFC system under continuous flow conditions. Several different surfactants were introduced as modifiers to activated carbon in an aqueous electrolyte with sodium sulfate (Na2SO4). A significant reduction in viscosity was found by adding sodium lignosulfonate, and as a consequence, a maxi-mum volumetric capacitance of 26 Fcm(-3) was achieved for the EFC system. A steady performance of the EFC system was observed for 200 h in terms of the specific capacitance (90 +/- 5 Fg(-1)); however, degradation in the power performance was observed. Membrane fouling was confirmed to be the major contributor to the power degradation, and a cleaning process using water was developed to partially restore the initial performance (approximate to 70%).