Electrochemical capacitors as attractive power sources

•Iodide solution is an attractive redox active electrolyte for long-term supercapacitor.•Iodide/vanadium species serve as conjugated redox couple electrolyte.•Gold is not a suitable current collector for iodide but stainless steel is.•Mesoporous character of carbon material is beneficial for redox active species.

The electrochemical performance of various carbon materials as supercapacitor electrodes with redox active electrolytes has been presented. In situ Raman investigation was carried out to show possible iodine species, polyiodides and carbon/iodine interactions during electrode polarization. Apart from the electrolyte also the kind of current collector plays an important role. Gold current collector is not adapted because of its reactivity with iodides whereas stainless steel is convenient. The conjugated iodide and vanadium species as the electrolyte were also investigated with Nafion separation. The best performance was obtained for AAC 1 and AAC 2 carbon material especially after adding 10% of carbon nanotubes.