Properties of Ce0.85Sm0.15O2-δ-CuO electrolytes for intermediate-temperature solid oxide fuel cells

Abstract

To improve the ionic conductivity of the common electrolyte Sm-doped CeO2 (SDC) for intermediate-temperature solid oxide fuel cells (IT-SOFCs) and to facilitate its production, we synthesized electrolyte materials SDC(Ce0.85Sm0.15O2-δ)-x mol %CuO (x = 0, 0.5, 1, 2) (named SDC, SDC + 0.5CuO, SDC + 1CuO, and SDC + 2CuO). The structural properties, surface micro-morphologies, and electrical properties of these four electrolyte materials were studied, as well as the performances of corresponding SOFCs. The results showed that all the materials had highly-crystalline CeO2 cubic fluorite structures and highly-dense ceramic electrolyte sheets. Adding an appropriate amount of CuO significantly reduced the grain-boundary resistance of SDC and improved its ionic conductivity. The SDC + 0.5CuO electrolyte showed the best ionic conductivity (σt = 0.088 Scm−1 at 800 °C), and the SOFC based on SDC + 0.5CuO had the highest output power, reaching a maximum power density of 380 mWcm−2 at 800 °C. In addition, the SOFC based on SDC + 0.5CuO exhibited good stability. The above results show that the optimal CuO amount was 0.5 mol% in our case, and SDC-CuO materials are promising candidates for use as electrolytes in IT-SOFCs.