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In recent years, SOFC technology has attained high interest for electrical power supply in vehicles as an Auxiliary Power Unit (APU) that operates independently from the main engine. In this paper, recent results are reported that have been achieved at DLR in adapting the DLR spray concept to the needs of an APU design based on plasma sprayed cells. Some major issues such as the porous metallic substrate, the characterization of the plasma sprayed cathode, the behavior of plasma sprayed cells during cycling experiments, and the development and application of an analytical tool for spatially-resolved electrochemical characterization are addressed.

The electrochemical behaviour of Ni-Ce 0.9 Gd 0.1 O 2− δ (Ni-CGO) with a NiO content of 2.5 and 70 wt.% was investigated by impedance spectroscopy. Symmetrical cells with yttrium-stabilized zirconia as electrolyte were prepared with screen printing and then sintered at 1250 °C for 5 h. The microstructure of the anode material after sintering was analysed by SEM. Impedance spectroscopy measurements were carried out in atmospheres containing H 2 , CH 4 and N 2 at various compositions humidified with 3% H 2 O in the temperature range 700–850 °C. No visible carbon deposition on both electrodes was found after measurements in variable atmospheres of H 2 and CH 4 (Balance N 2 ) despite the high content of Ni. However, carbon deposition occurred on the anode with 70 wt.% NiO during continuous exposure in stability testing for 90 h in 97% CH 4 /3% H 2 O.

The electrochemical behaviour of Ni-Ce 0.9 Gd 0.1 O 2-δ with a NiO content of 2.5 wt% and 70 wt% was investigated. Symmetrical cells with yttrium stabilized zirconia as electrolyte were prepared by screen printing the electrodes and then sintering them at 1250°C for 5 h. Impedance spectroscopy measurements were carried out in 10 % CH 4 / 90% N 2 and CH 4 humidified with 3% H 2 O in the temperature range 700°C to 850°C. The microstructure of the anode material before and after measurements was analysed by SEM. No visible carbon deposition on both electrodes was found after electrochemical measurements despite the high content of Ni. However, carbon deposition occurred on the anode with 70 wt% NiO during continuous exposure for 90 h in 97% CH 4 / 3% H 2 O. The anode with 70 wt% NiO was investigated by impedance spectroscopy at high steam/methane ratios as well.