Tape cast complex electrolytic membrane for sofc/soec applications

The interest in ceramic multilayers arises from the possibility to tailor their functional properties designing a particular structure. Functional-graded or sandwiched ceramic multilayers are for example well-known structure used to effectively modulate their mechanical, thermal and electrical properties along the thickness of the final device. This study in particular shows the possibility to produce a dense/porous/dense BaCe0.85Y0.15O3-? (BCY) sandwich-structure electrolyte by tape casting for a Dual Membrane Cell (DM-Cell). This cell is a 3-chambers concept that can reversely operate as electrolyser. It combines all the advantages of SOFCs and PCFCs without the drawbacks associated with the presence of water at the electrodes. Water is in fact produced and evacuated through a separate chamber in a mixed H+ and O2- conducting porous membrane, named Dual Membrane (DM). Due to the demonstrated mixed (oxide ion and proton) conductivity of the BCY, the two dense BCY layers act as the H+ and O2- conducting electrolytes, while the porous layer acts as DM. In this work dense/porous/dense BCY structures were successfully produced by tape casting. Each step of the production process (slurry formulation, lamination and thermal treatments) were thoroughly investigated. The sandwich structure was formed by in-situ sintering layer-stacked green tapes with or without pore former. The process optimization led to flat, crack-free, 600 µm thick BCY discs (Ø = 30 mm) with a well-controlled microstructure (Figure 1). The samples obtained were carefully characterized either in SOFC and SOEC mode. Post-mortem SEM analyses were also performed onto the samples.