Metal-supported solid oxide fuel cells (MS-SOFC) display a number of advantages over conventional all-ceramic SOFCs, including low-cost structural materials (e.g. stainless steel), mechanical ruggedness, excellent tolerance to redox cycling, and extremely fast start-up capability. These properties make MS-SOFCs ideally suited for range extenders in vehicles due to tolerance to thermal fluctuations following load changes or intermittent fuel flow. Directly fueled with ethanol or ethanol-water mixture, MS-SOFCs provide promising alternative for mobile applications.

In this talk, the recent progress on performance and durability of symmetric MS-SOFCs, pioneered at LBNL, will be addressed. The development of new electrolyte, new cathode and anode catalysts, optimized cell configuration, and processing techniques will be discussed. The catalyst infiltration technique allows for flexible and layered electrode composition, depending on the system applications and fuels. Our current state-of-the-art MS-SOFCs achieve power density of ≥1.5 W/cm² at 700 °C and ≥2.85 W/cm² at 800 °C when fueled with humidified hydrogen which is, to the best of our knowledge, the highest performance reported in the literature for stainless steel MS-SOFCs. However, catalyst coarsening and Cr deposition from the stainless steel metal support are known to occur¹, and the primary degradation mechanisms are elucidated and tackled to improve the durability. The cell area specific resistance (ASR) of <0.144 W∙cm² at 700 °C meets the projected requirements for commercialization in vehicles. Initial studies on button cells fueled with ethanol/water mixture are investigated and further efforts towards increasing power density and durability are addressed.

¹M.C. Tucker, Journal of Power Sources, 369, 6-12, Nov. 2017.

Acknowledgments

The information, data, or work presented herein was funded in part by the Advanced Research Projects Agency – Energy (ARPA-E), U.S. Department of Energy under work authorization number 13/CJ000/04/03. This work was funded in part by the U.S. Department of Energy under contract no. DE-AC02-05CH11231.

Figure 1. (a) Illustration of a symmetric MS-SOFC configuration developed at LBNL, and (b) the highest cell performance obtained so far on the stainless steel MS-SOFCs.