Ultra-thin film solid oxide fuel cells utilizing un-doped nanostructured zirconia electrolytes

Abstract

Aliovalently-doped zirconia (ZrO2) systems such as yttria-stabilized ZrO2 (YSZ) have been explored as ionic conductors for solid oxide fuel cells (SOFCs) owing to their high ionic conductivity and exceptional mechanical and chemical stability. Thin film micro-SOFCs (mu-SOFCs) with free-standing membranes create an opportunity for reduced temperature operation with the need to engineer the various materials components. In this study, we have fabricated mu-SOFCs composed of nominally pure ZrO2 electrolytes (down to sub-10 nm thickness) prepared by room temperature photon-assisted oxidation of Zr precursor metal films and nanoporous Pt electrodes and report on fuel cell performance up to similar to 500 degrees C in hydrogen. The mu-SOFCs exhibit maximum power density of similar to 33 mW cm(-2) with open circuit voltage of similar to 0.91 V at 450 degrees C. The electrolyte thickness-dependent functional properties of the mu-SOFCs are discussed in detail along with thermo-mechanical stability and microstructural studies. The results could serve as a benchmark to understand doping effects in designing thin film fast-ion conducting zirconia-based electrolytes for low temperature fuel cell operation. (C) 2012 Elsevier B.V. All rights reserved.