Solid oxide cells (SOCs) are electrochemical cells that can be run reversibly in two directions: they can be used as an electrolyzer to produce green hydrogen (or other cleaner chemical fuels) when ‘extra’ electricity is available from wind or solar cells. When electricity is needed (e.g., during night), they can be run as a fuel cell to convert hydrogen to electricity. Since SOCs are highly efficient, they are ideally suited for cost-effective co-generation of electricity and green hydrogen. However, commercialization of SOC technology is hindered by the lack of advanced materials with desirable properties for reversible dual-mode operation. This presentation will highlight the critical scientific challenges facing the development of electrolyte, electrode, and catalyst materials for SOCs, the strategies for enhancing electrical conductivity, electro-catalytic activity, and durability of these materials, and our recent progress in the development of new materials and in probing the mechanism of electrode reactions using a combination of theoretical and experimental techniques. For example, the introduction of proper dopants and careful engineering of defect chemistry have resulted in a new class of electrolyte and electrode materials that not only show better chemical stability but also have much improved ionic conductivity and catalytic activity. Furthermore, single cells based on these new materials achieve very high performance and durability in both the fuel cell and the electrolysis mode. Also, it will be demonstrated that in situ/operando characterization of materials under typical operating conditions is imperative to gaining insight into rational design of new materials.

Meilin Liu is the Hightower Chair and Regents' Professor of the School of Materials Science and Engineering at Georgia Institute of Technology, Atlanta, Georgia. He received his BS from South China University of Technology and both MS and PhD from the University of California at Berkeley. His research interests include design, fabrication, in situ/ operando characterization, and simulation of membranes, thin films, and nanostructured electrodes in devices for energy storage and conversion, aiming at achieving rational design of materials and structures with unique functionalities. He holds 31 U.S. patents, co-organized 11 international symposia and workshops, co-edited 7 proceedings volumes, delivered ~200 plenary, keynote, or invited lectures, and published ~650 refereed articles. Dr. Liu is a fellow of the International Association of Advanced Materials (IAAM, 2021), Electrochemical Society (ECS, 2012), and American Ceramic Society (ACerS, 2011). Professional awards include Highly Cited Researcher (since 2018), the Charles Hatchett Award (UK IM3, 2018), HTM Outstanding Achievement Award (ECS, 2018), Kolon Faculty Fellow (2017), Outstanding Faculty Research Author Award (Georgia Tech, 2013 and 1997), Ross Coffin Purdy Award (ACerS, 2010), Outstanding Achievement in Research Program Development Award (Georgia Tech, 2003), Sustained Research Award (Sigma Xi, 2003), and National Young Investigator Award (NSF, 1993).