Electrochemical performances of a reversible high temperature fuel cell based on a mixed anionic-protonic conductor

This paper deals with the fabrication and study of a high temperature solid electrolyte supporting electrochemical cell operating as SOFC and SOEC. The cell is based on the idea of a dual membrane electrolyte, which has the advantage to separate the cell in three different chambers: hydrogen side, oxygen side and dual membrane (D.M.), where water production-SOFC or splitting-SOEC takes place. The tape casted supporting electrolyte is constituted by a dense/porous/dense tri-layer, made of BaCe0.85Y0.15O3-? (BCY), which is a mixed ionic conductor. The electrolyte sandwich was formed by in-situ sintering of stacked green tapes with or without pore former. The process optimization (slurry formulation, lamination and thermal treatments) led to flat, crack-free, 580 ?m thick BCY discs with a well-controlled microstructure. Platinum electrodes were deposited on both sides of the sandwich-structured electrolyte. The cell was then electrochemically studied under different operating conditions of temperature, overpotentials and gas feeding, either in SOFC and SOEC mode. From the presented results it can be highlighted that despite the dense electrolyte layers were kept thick and the electrodes were made of platinum, the electrochemical study of the cell show: i) a promising power density, ii) an interesting reversibility SOFC/SOEC, iii) a proved splitting of the water contained in the porous central membrane when the cell operates as an electrolyser (SOEC). Degradation of the cell performance is also focused.