Proton Conducting Micro-Solid Oxide Fuel Cells with Nanoscale Palladium Interlayers

We will consider solid oxide fuel cells with electrolyte membranes whose dimensions approach the tunneling limit. Suspended oxide membranes allow exploring ionic and electronic conduction in quasi-2D structures without interference from the substrate at temperatures below 600C. One can consider minority carrier transport mechanisms at such lengthscales to design solid electrolytes wherein dc ionic conductivity alone may not be the critical factor. The thermo-mechanical stabilty of such membranes are in turn closely related to the electroneutrality conditions under the operating environment. Cation valence change driven lattice distortions can profundly modify the strain states and dictate material selection. At the same time, oxide heterostructures can be fabricated in freestanding manner to explore the possibility of local energy storage in an electrode at such low temperatures. We will consider opportunities with Mott insulators for the same wherein the onset of correlated metallic state is closely linked to disorder. Representative examples of fuel cells operating directly in methane will be presented.