Electrolytes for Low Temperature Solid Oxide Fuel Cells

Abstract

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 sup- porting and gas-permeable substrate. The dense YSZ electrolyte was deposited by combining atomic layer deposition (ALD) and sputter- ing 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 390nmwas successfully fabricated on porous AAO with this combined deposition method, and the open circuit voltage (OCV) of the cell with this electrolyte was veri- fied to reach a high value of 1.14 Vat 350 ?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 ?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.