Barium- and Strontium-Containing Anode Materials toward Ceria-Based Solid Oxide Fuel Cells with High Open Circuit Voltages

Developing ceria-based solid oxide fuel cells (SOFCs) with low cost, high power density, and, in particular, high working efficiency is of great significance to practical applications. In this work, Ba- and Sr-containing composites (Ni-Ba1-xSrxCe0.7Zr0.1Y0.2O3−δ) were for the first time proposed and evaluated as anodes for Ce0.8Sm0.2O1.9 (SDC)-based SOFCs. Both Ba and Sr diffusion occurs at elevated temperatures during fabricating anode-supported half-cells; correspondingly, a thin electron-blocking interlayer is formed in situ at the anode/electrolyte interface. The presence of Ba ensures the formation of a BaCeO3-based electron-blocking layer, which has a very high ion transport number and completely eliminates the internal short circuit current across the SDC electrolyte. Sr incorporation can substantially promote the sintering activity of the anode and electrolyte and, hence, reduces the sintering temperature of the half-cells to 1150 °C. The electrochemical performance of the SDC-based cells varies significantly with the anode composition. Ni-Ba0.9Sr0.1Ce0.7Zr0.1Y0.2O3−δ is demonstrated to be the optimal anode composition showing high open circuit voltages (1.038 V at 650 °C) and peak power densities (677 mW cm-2 at 650 °C). These results present substantial progress in developing leakage current-free ceria-based SOFCs and also provide new insight into designing new cathode materials/structures for efficient ceria-based solid oxide electrolyzer cells.