Reduction of porous carbon/Al contact resistance for an electric double-layer capacitor (EDLC)

► The internal resistance of the EDLC devices was analyzed using EIS combined with an equivalent circuit model. ► The carbon/Al contact resistance was shown to be greatly reduced by using an Al4C3 nano whiskers modified Al current collector. ► As the EDLC cell was scaled up, its normalized resistances were also increased as a result of non-uniformity in electrode thickness and pressure on the cell's body. Carbonaceous materials are commonly used to fabricate electrodes for electric double-layer capacitors (EDLCs) or supercapacitors. The high contact resistance between the carbon active layer and the Al current collector can decrease capacitor energy and power performance, and shorten the lifetime of the capacitor. In this report, the sources of carbon based EDLC internal resistance were explored using electrochemical impedance spectroscopy (EIS). An equivalent circuit model was coupled with the EIS data for the analyses. The EDLC cells were made from symmetric carbon/Al electrodes and operated in organic electrolyte. The analysis results showed the effects of pressure and modified Al on the contact resistance, where a novel, carbon modified Al collector with Al4C3 nano whiskers greatly reduced the contact resistance. Finally the effect of scale-up on the internal resistance was discussed.