Bi-Layer Structured Co-Ionic Composite Electrolytes Solid Oxide Cells for Stable Fuel Cell and Electrolysis Operations

Abstract

A bilayer comprising BCY (BaCe0.85Y0.15O3-d) - GDC (Gd0.2Ce0.8O2-d) at anode side and BZY (BaZr0.85Y0.15O3-d) - NDC (Nd0.1Ce0.9O2-d) at cathode side, was designed for improving the stability for intermediate solid oxide fuel cells. Two Pt probes were embedded in each electrolyte layer close to anode and cathode sides of electrolyte for the estimation of the local electronic conduction, which is correlated to the cell stability under negative voltage operation caused by cell imbalance. Mixed ionic and n-type electronic conduction was locally developed in the BCY-GDC region near the anode side while mixed ionic and p-type electronic conduction was locally developed in the BZY-NDC near the cathode side. On the other hand, the middle electrolyte region exhibited predominantly ionic conduction which was an effective electrolyte region. Contrary to single layer structured composite electrolytes, the bi-layered composite electrolyte cell was stably operated without electrode/electrolyte delamination under negative voltage conditions, by means of local electronic conduction. Hence, we suggest the composite electrolytes configuration, such as cathode/ BCY-GDC / BZY-NDC / anode, for stable fuel cell and electrolysis operations.