Role of surface functional groups in ordered mesoporous carbide-derived carbon/ionic liquid electrolyte double-layer capacitor interfaces.
Ordered mesoporous carbide-derived carbon (OM-CDC) with a specific surface area as high as 2900 m(2) g(-1) was used as a model system in a supercapacitor setup based on an ionic liquid (IL; 1-ethyl-3-methylimidazolium tetrafluoroborate) electrolyte. Our study systematically investigates the effect of surface functional groups on IL-based carbon supercapacitors. Oxygen and chlorine functionalization was achieved by air oxidation and chlorine treatment, respectively, to introduce well-defined levels of polarity. The latter was analyzed by means of water physisorption isotherms at 298 K, and the functionalization level was quantified with X-ray photoelectron spectroscopy. While oxygen functionalization leads to a decreased capacitance at higher power densities, surface chlorination significantly improves the rate capability. A high specific capacitance of up to 203 F g(-1) was observed for a chlorinated OM-CDC sample with a drastically increased rate capability in a voltage range of ±3.4 V.
Leibniz-Institute for Solid State and Materials Research (IFW) Dresden e.V., Institute for Complex Materials , P.O. Box 270116, D-01171 Dresden, Germany.
Katja
K
Pinkert
Martin
M
Oschatz
Lars
L
Borchardt
Markus
M
Klose
Martin
M
Zier
Winfried
W
Nickel
Lars
L
Giebeler
Steffen
S
Oswald
Stefan
S
Kaskel
Jürgen
J
Eckert