Characterization of the electrochemical and ion-transport properties of a nanoporous carbon at negative polarization by the single-particle method
2006 (English)In: Journal of the Electrochemical Society, ISSN 0013-4651, Vol. 153, no 1, A48-A57 p.Article in journal (Refereed) Published
In this work, the electrochemical processes occurring in a nanoporous carbon, obtained from silicon carbide and used as negative electrode material for supercapacitors, have been investigated by means of the single-particle microelectrode method. The processes studied deal with hydrogen adsorption, evolution, and oxidation using 6 M KOH as electrolyte. It was found that adsorption of hydrogen started at -0.5 V, hydrogen evolution at -1.4 V vs Hg vertical bar HgO, and that hydrogen oxidation occurs in two steps. The first oxidation process takes place between 0 and 0.1 V, shown by a well-defined current peak on the voltammograms. The second oxidation stage occurs between 0.1 and 0.5 V, indicated by a successive increase in current with the number of cycles. It was also found that after the first oxidation process, subsequent cycling between -0.5 and -1 V leads to a larger accumulation of hydrogen inside the nanopores and to a decrease of the effective diffusion coefficient (D-eff) of potassium ions. Subsequent oxidation, in a second process, leads to a total consumption of hydrogen and to an increase of D-eff.
Place, publisher, year, edition, pages
2006. Vol. 153, no 1, A48-A57 p.
IdentifiersURN: urn:nbn:se:kth:diva-5042DOI: 10.1149/1.2129670ISI: 000234142400008ScopusID: 2-s2.0-33645511421OAI: oai:DiVA.org:kth-5042DiVA: diva2:7692