A New Family of Proton-Conducting Conducting Materials in Layered Oxides

Abstract

To identify a good ionic conducting material for use as electrolyte for intermediate temperature solid oxide fuel cells (IT-SOFCs) remains a big challenge. In this report, we demonstrate that good proton conductor can be obtained in transition element rich intercalation materials such as LixAl0.5Co0.5O2. OCV of 1.0 ~ 1.1V was observed for a H2/air fuel cell at temperature 475 – 575 °C indicating it is nearly a pure ionic conductor under fuel cell operating conditions. A power density of 173 mW cm-2 has been achieved at 525 °C with a thick electrolyte (0.79 mm thick) when silver was used as both cathode and anode. The ionic conductivity of LiAl0.5Co0.5O2 was 0.1 S/cm at 500 °C, deduced from the series resistance of the H2/air fuel cell. This is the highest among known poly-crystalline proton-conducting materials. This study will provide a new approach to discover new proton conducting materials for use in IT-SOFCs. It is expected that an ideal proton-conducting oxide may be identified in layered oxides.