Based Fuel Electrodes for SOFC

It appears that instead of a simple electrode a complicated one emerged, and a suitable (cheap and redox stable) current collector material has not yet been demonstrated. Nevertheless, ceria based anodes have important advantages over conventional Ni-based anodes, namely the ability to endure repetitive oxidation and reduction (redoxing) and the ability to avoid (or tolerate) carbon deposition from 

Back in 1964, Mdbius and Rohland showed that ceria could work as an anode in an SOFC fuelled with H2 and CO, and shortly after Takahashi et al. described Ceo6Yo.40i 8 and CcoeLao Oi s as being excellent anode materials for SOFC. Since then, a number of studies have been carried out. Cells with a ceria anode may have a performance similar to cells with Ni-YSZ- electrodes in hydrogen at 1000°C. 

Ceria has also been used as the ceramic part in nickel - or ruthenium - cermet anodes for hydrogen oxidation.Beneficial effects have been reported and interpreted as being probably due to the broadening of the three-phase boundary zone width. 

At temperatures below 1000°C the doped ceria has a considerable larger polarisation resistance, Rp, even in case of cermet with nickel. (The reaction rate is proportional to 1/Rp). At the lower temperatures the reaction may be accelerated by addition of fine Ni particle to the surface of the doped ceria. Impedance spectra at 850°C of Ni/Ceo jGdo iO, 95 cermet electrodes with and without small amounts of fine Ni particles (probably of nanometer size) are given in Fig. 15.13. The impedance is significantly affected. The dominant low frequency arc (fsummit = 1 Hz) 

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