Nanoscale Compositionally Graded Thin-Film Electrolyte Membranes for Low-Temperature Solid Oxide Fuel Cells

Controllable fabrication of compositionally graded Gd0.1Ce0.9O2‐δ and Y0.16Zr0.84O2‐δ electrolytes using co‐sputtering is demonstrated. Self‐supported membranes were lithographically fabricated to employ the new electrolytes into thin film solid oxide fuel cells. Devices integrating such electrolytes demonstrate performance of over 1175 mW cm−2 and 665 mW cm−2 at 520 °C using hydrogen and methane as fuel, respectively. The results present a general strategy to fabricate nanoscale functionally graded materials with selective interfacial functionality for energy conversion. Compositionally graded thin film oxide electrolytes are synthesized by co‐sputtering for use in low‐temperature solid oxide fuel cells. The synthetic method is broadly relevant for the fabrication of nanoscale functionally graded materials with selective interfacial functionality for energy conversion. The high power densities in H2 and methane fuels are demonstrated and interfacial features are discussed.