Anodes Derived from Fluorite-Type and Perovskite-Type Metal Oxides for SOFCs
In the present study, mixed ionic electronic conducting (MIECs) Ce0.8Y0.1Mn0.1O2-d and BaZr0.1Ce0.7Y0.1M0.1O3−δ (M = Ni and Co), and composite Ni and Ba0.5Sr0.5Ce0.6Zr0.2Gd0.1Y0.1O3-δ (BSCZGY) have been investigated as SOFC anodes. The cell performance of a button cell: Ce0.8Y0.1Mn0.1O2-d/Zr0.84Y0.16O2-d/La0.6Sr0.4MnO3+Zr0.84Y0.16O2-d was tested at 800 oC in 3 % H2O-H2 as a fuel and air as an oxidant. There was an obvious enhancement of the cell performance upon exposure to 10 ppm H2S-H2 for 48 h. Another area of the MIEC anodes development involves investigation of perovskite-type BaZr0.1Ce0.7Y0.1M0.1O3−δ (M = Ni and Co). The BaZr0.1Ce0.7Y0.1Ni0.1O3−δ compound shows a promising low polarization resistance of 0.4 Ω.cm2 at 800oC in H2. Low polarization resistance of the BaZr0.1Ce0.7Y0.1Ni0.1O3−δ perovskite, as a non-composite anode without any additional electron conductive phase, makes it a promising material for SOFC anodes.
Proton conducting doped BaCeO3 materials is the frontrunners as electrolyte in the field of low temperature (400-700 oC) proton-SOFCs. A and B site co-doped Ba0.5Sr0.5Ce0.6Zr0.2Gd0.1Y0.1O3-δ has shown good chemical stability in CO2 and humid atmospheres at elevated temperature . In the present work, anode performance of Ni-BSCZGY composites (with Ni: BSCZGY ratios as 30:70, 40:60 and 50:50) has been studied. Screen-printing and co-firing processes were employed to make symmetrical cell: Ni-BSCZGY/BSCZGY/Ni-BSCZGY. Area specific resistance (ASR), capacitance and activation energy values were studied to evaluate the electrochemical performance of the anode composites. 50:50 composite shows the lowest ASR value among the current investigated anode compositions (30:70 and 50:50).
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