Modification of Al current collector/active material interface for power improvement of electrochemical capacitor electrodes

This paper presents results about carbon nanofibers (CNFs) synthesis and their use as surface treatments for Al current collector for carbon electrochemical capacitors in organic electrolyte. CNFs have been successfully synthesized on a pretreated Al substrate; the pretreatment of Al consists of an etching followed by a carbonaceous sol-gel deposit. Performances of cells assembled with pretreated Al and pretreated Al coated by CNFs have been compared by using galvanostatic cycling measurements. Internal resistances as low as 0.4 Omega cm(2) are obtained for cells using CNF-treated Al. The increase of the surface contact and interface conductivity between the Al and the active material are responsible for this internal resistance decrease. The capacitance obtained for the two cells is the same (95 F g(-1) of activated carbon). Performances [both equivalent series resistance (ESR) and capacitance] are stable over 10 000 cycles, proving the great efficiency of surface treatments.