Solid oxide fuel cells incorporating doped lanthanum gallate films deposited by radio-frequency magnetron sputtering at various Ar/O-2 ratios and annealing conditions

摘要

In this study, we prepared solid oxide fuel cells (SOFCs) incorporating a dense La0.87Sr0.13Ga0.88Mg0.12O3-delta (LSGM) film deposited by radio-frequency (RF) magnetron sputtering on an NiO-Sm0.2Ce0.8O2-delta (NiO-SDC) anode substrate. The influences of the Ar-O-2 deposition atmosphere and the subsequent annealing conditions on the characteristics of the LSGM film and on the performance of the resulting SOFCs was investigated. LSGM targets with La0.76Sr0.24Ga0.63Mg0.37O3-delta composition and a deposition atmosphere with Ar/O-2 ratios ranging from 10/0 to 5/5 were used throughout the study. Owing to the amorphous nature of the as-deposited LSGM films, the film deposited in an Ar/O-2 = 10/0 atm required post-annealing at 950 degrees C for 4 h for crystallization and removal of the SrLaGa2O7 content, while the films deposited at lower Ar/O-2 ratios required higher crystallization temperatures: for instance, the films deposited at Ar/O-2 = 6/4 had to be annealed at 1100 degrees C for 2 h. The anode-supported substrates were then screen-printed with a La0.6Sr0.4Co0.2Fe0.8O3-delta (LSCF)-LSGM cathode layer and fired to form SOFC cells. The single cell incorporating an LSGM film with La0.87Sr0.13Ga0.88Mg0.12O3-delta composition deposited in a pure Ar atmosphere exhibited the lowest cell resistance and thus the highest maximum power density (MPD) at all operating temperatures. The total resistance of the single cell incorporating a 4.3 mu m-thick LSGM film decreased from 0.386 to 0.121 Omega cm(2) as the temperature increased from 650 to 850 degrees C, and the open circuit voltages ranged from 0.941 to 0.861 V. The maximum power density of the single cell was 0.422, 0.736, and 1.105 W cm(-2) at 650, 750, and 850 degrees C, respectively.