Methane-Fueled Proton-Conducting Ceramic Fuel Cell Stacks

Abstract

We present our recent work on scale-up and stack development of fuel cells based on proton-conducting ceramic materials. Through steady improvement in materials and fabrication methods, protonic ceramics are emerging from the laboratory as potential solutions in electricity generation, energy storage, and chemical synthesis. “Button-scale” protonic ceramic fuel cells (PCFCs) based on barium zirconates have demonstrated high power density at low operating temperatures, reaching 450 mW / cm2 at 500 ºC under hydrogen fuel, and 300 mW / cm2 at 550 ºC under direct methane-steam fuel. While these materials show great promise, scale up of protonic-ceramic fuel cells beyond the “button-cell” level remains limited. In this presentation, we review our progress in extending previous button-cell experiments to small fuel-cell stacks. First, fabrication procedures have been developed to increase PCFC active area by a factor of 10. These planar, circular membrane electrode assemblies (MEAs) are packaged within the stack architecture shown in the figure. MEAs are bonded within a ceramic frame, and the frame is packaged within ferritic-steel interconnects. Numerous multi-cell stack prototypes have been demonstrated. A three-cell stack based on BaCe0.2Zr0.6Y0.2O3-d (BCZY26) electrolyte shows near-theoretical open-circuit voltage and promising power density under methane fuel (183 mW / cm2 at 500 ºC). In this presentation, we will review our continuing efforts to improve the performance and durability of protonic-ceramic fuel cell stacks. Figure 1