(687c) Experimental Evaluation of Electrode-Supported Solid-Oxide Cells for High-Temperature Electrolysis

Anode-supported cells represent some of the highest performing solid oxide fuel cells currently under development. The nickel cermet material, which serves as the anode in the fuel cell mode and the cathode in the electrolysis mode, has relatively high electronic conductivity and is therefore a logical choice for use as the mechanical support layer in electrode-supported cells. In an anode-supported SOFC, the anode is typically 1 ? 1.5 mm in thickness while the electrolyte thickness can be as low as 10 µm. In the fuel-cell mode, steam diffusion away from the functional layer can be readily pressure-driven. In the electrolysis mode, however, it may be preferable to use an oxygen-electrode-supported cell to reduce the concentration overpotential associated with steam diffusion through the thickness of the electrode toward the functional layer. The typical oxygen-side electrode material for the present cells is lanthanum-strontium manganite (LSM) perovskite. Electrode-supported cells are currently being evaluated to determine their performance in the electrolysis mode. This paper will provide results of a experimental study of electrode-supported electrolysis cells. Comparisons will be made between performance of the cells in the fuel cell mode and in the electrolysis mode. The effect of steam fraction will be examined. The cells will also be characterized using impedance spectroscopy. Long-term degradation in the two modes of operation will also be evaluated.