Study of reversible SOFC/SOEC based on a mixed anionic-protonic conductor

This paper deals with the fabrication and electrochemical study of a high temperature solid electrolyte supporting cell operating as SOFC (Solid Oxide Fuel Cell) and SOEC (Solid Oxide Electrolysis Cell). The cell is based on a dual membrane (DM) electrolyte design, advantageously separating the cell into three different chambers: hydrogen side, oxygen side, and dual membrane (DM), where H2O production or splitting takes place in SOFC or SOEC mode respectively. The supporting electrolyte consists of a dense/porous/dense tri-layer, exclusively made of BaCe0.85Y0.15O3-delta (monolithic design), which is a mixed anionic-protonic conductor. The assembly was fabricated by tape casting, adding pore formers to control porosity. The cell was then electrochemically studied under different operating conditions of temperature, overpotentials and gas feeding, either in SOFC and SOEC mode. From the results presented here, it can be observed that, in spite of dense and thick electrolyte layers and platinum electrodes, the electrochemical study of the cell showed: (i) promising power density, (ii) interesting SOFC/SOEC operating mode reversibility, (iii) proved H2O production in the porous dual membrane when the cell operates as a fuel cell, and proved splitting of the H2O molecules contained in the porous dual membrane when the cell operates as an electrolyser. Investigations of cell performance degradation were also conducted.