(Invited) Electrode Engineering of Solid-Oxide Electrochemical Cells at National Energy Technology Laboratory

Abstract

The National Energy Technology Laboratory (NETL) Solid Oxide Fuel Cell (SOFC) Team performs fundamental SOFC technology evaluation, enhances existing SOFC technology, and develops advanced SOFC concepts in support of the U.S. Department of Energy SOFC Program. Program targets include a reduction in performance degradation to 0.2% per 1000 hours and a system cost of $900 per kilowatt. Research and development is essential to meet these targets. Research efforts are broadly focused on an investigation of cell and stack degradation, electrode engineering, grid integration challenges, and system analysis. The research approach is targeted to specifically address SOFC program technology development goals, especially regarding reducing stack costs, increasing cell efficiency, and increasing cell reliability and robustness. The goal of these efforts is to transfer technology that facilitates commercial acceptance of SOFC technology. This is accomplished through close collaboration with SOFC commercial developers, national laboratories, and academic institutions. NETL system-level analysis has shown that a critical consideration for reducing the cost of SOFC technology is the enhancement of electrode performance and longevity through materials and microstructure engineering. Within this scope is the special consideration of cell production costs and operating temperature. Specifically, at NETL, nano-electrocatalyst infiltrations have been a successful operation by scaling up the patented technology to a commercially-relevant scale, partnering with industrial manufacturers. The effort has continued to the construction of a scaffold microstructure that is optimized for surface modification and the development of gel-derived high surface area electrodes. Electrode materials selection has been made through a computational approach that uses electronic structure and energetics in conjunction with thermodynamics and statistical physics, identifying multicomponent oxides with high oxygen reduction reaction activity and stability. Highly reliable electrical conductivity relaxation analysis confirmed the predicted electrode materials’ superior surface exchange property when compared to the state-of-the-art lanthanum strontium cobalt ferrite. The developed electrode engineering techniques have been applied for reversible solid-oxide cell operation as well as single mode solid-oxide cells to stabilize electrodes while maintaining improved performance and longevity.