Page 192 - High Temperature Solid Oxide Fuel Cells Fundamentals, Design and Applications

Anodes 369

much thicker anode layers are used in order to provide sufficient conductivity to
transport electrons out to the interconnect.
Operation of anodes on fuels other than hydrogen is commercially necessary,
and challenging because of carbon deposition. In general, pre-reforming of
hydrocarbons is carried out before the fuel contacts the anode. Direct internal
reforming is possible with nickel cermet anodes, but carbon deposition can be a
problem in long-term operation. Other possible anode metals, such as copper,
can prevent carbon formation but their properties are not entirely satisfactory.
One strand of current research is towards stable direct oxidation anodes. with
modified cermets incorporating copper and ceramics like ceria; a further option
lies in the identification of mixed conducting ceramics with sufficient
electrocataIytic activity to function alone without any metal as anodes. The
ultimate challenge is to produce anodes which can directly oxidise hydrocarbons.
Indications are that this is possible and represents ongoing anode development.

References
H. S. Spacil, US Patent 3,558,360; filed October 30, 1964, modified
November 2,1967, grantedMarch 31,1970.
T. Ogawa, T. Ioroi, Y. Uchimoto, Z. Ogumi and Z.-I. Talrehara, in Solid
Oxide Fuel Cels III, The Electrochemical Society Proceedings, Pennington,
NJ, PV 93-4,1993,~. 479.
E.Baur andH. Preis, Z. Elektrochem., 43 (1937) 727.
H.-H. Mobius, J. Solid State Electrochem., 1 (1 99 7) 2; this work, Chapter 2.
S. C. Singhal, in Solid Oxide Fuel Cels 111, The Electrochemical Society
Proceedings, Pennington, NJ, PV 93-4,1993, p. 665.
J.-H. Lee, H. Moon, H.-W. Lee, J. Kim, J.-D. Kim andK.-H. Yoon. Solid State
Ionics, 148 (2002) 15.
S. Primdahl, B. F. Scarensen and M. Mogensen, J. Am. Cerarn. Soc., 83
(2000) 489.
D. Skarmoutsos, F. Teitz and P. Niikolopoulos, Fuel Cells, 1 (2001) 243.
T. Wagner, R. Kirchheim andM. Ruhle. Actallletall. Mater,, 40 (1992) S85.
A. RinguedC, J. A. Labrincha and J. R. Frade. Solid State Ionics, 141-142
(2001) 549.
H. Itoh, Y. Heie, T. Yamamoto, M. Mori and T. Watanabe, in Solid Oxide
Fuel Cells VU, eds. H. Yokokawa and S. C. Singhal, The Electrochemical
Society Proceedings, Pennington, NJ, PV2001-16,2001, p. 750.
P. Holtappels, Julich Research Centre Report 3414, 1997/Thesis,
University of Bonn.
R. N. Basu, G. Blass, H. P. Buchlrremer, D. Stover, F. Tietz, E. Wessel and
I. C. Vinke, in Solid Oxide Fuel Cells VII, eds. H. Yokokawa and S. C.
Singhal, The Electrochemical Society Proceedings, Pennington, NJ,
Pv2001-16,2001, p, 995.
Research Centre Julich website http://www.sofc.de (2002).
P. van Heuveln, Thesis, University of Twente, Netherlands, 199 7, p. 167.