Pressurized single cell testing of solid oxide cells

Pressurized operation of Solid Oxide Cells (SOCs) enhances the performance in the fuel cell mode and is mandatory for coupling with gas turbines. For electrolysis, energy demand and balance of plant to pressurize hydrogen or syngas can be reduced. Today's facilities for pressurization of SOCs rely on voluminous pressure vessels that enclose the cells/stacks. Inside such vessel, fuel- and oxidant pressures have to match the vessel pressure to avoid a deterioration of the cells/stacks. Here, a single cell is operated without a pressure vessel in a metallic cell housing sealed towards the cell by a glass-ceramic sealant. Any differential pressure is avoided by a downstream combustor, an approach that is limited to test benches. In our experiments we found that this sealing concept can withstand pressure drops of up to 10 bar towards ambient pressure even after a full thermal cycle. As to be expected from numerous previous studies, open-circuit voltage as well as performance increased significantly with increasing pressure. The power density increased by 20 % in air/dry H2 at 850 °C and 11 bara.