Combinatorial deposition of a dense nano-thin film YSZ electrolyte for low temperature solid oxide fuel cells

This paper presents a combinatorial deposition of a nano-thin film yttria-stabilized zirconia (YSZ) electrolyte deposited on a nanoporous anodic aluminum oxide (AAO) membrane, which serves as a supporting and gas-permeable substrate. The dense YSZ electrolyte was deposited by combining atomic layer deposition (ALD) and sputtering in an attempt to realize a pinhole-free electrolyte on a porous structure with a minimum electrolyte thickness. The YSZ electrolyte with an overall thickness of about 390 nm was successfully fabricated on porous AAO with this combined deposition method, and the open circuit voltage (OCV) of the cell with this electrolyte was verified to reach a high value of 1.14 V at 350 degrees C under an atmosphere of pure hydrogen and ambient air. The fuel cell performance reached power densities of 88, 129, and 180 mW cm(-2) at 350, 400, and 450 degrees C, respectively, and has been so far the highest attainable for a nanoscale thin film electrolyte on a porous substrate at such low temperatures. The addition of the pre-ALD YSZ layer also serves to confine the anode morphology and thus enhance the thermal stability of the metal electrodes.