New Layered Proton‐Conducting Oxides LixAl0.6Co0.4O2 and LixAl0.7Co0.3O2

Abstract

AbstractSingle‐phase layered oxides with nominal composition LiAl0.6Co0.4O2 and LiAl0.7Co0.3O2 were synthesised and tested as electrolytes for H2/air fuel cells. The maximum current and power densities of 382 mA cm−2 and 108 mW cm−2, respectively, were achieved at 650 °C when a 0.70 mm‐thick LiAl0.6Co0.4O2 pellet was used as the electrolyte. The ionic conductivity of LiAl0.7Co0.3O2 was 4.0×10−2 S cm−1 at 725 °C, which was derived from the series resistance of the impedance spectra of the H2/air fuel cells. For LiAl0.6Co0.4O2, the highest ionic conductivity was 7.7×10−2 S cm−1, observed at 625 °C. In the LiAl1−yCoyO2 series, the proton conductivity and working temperature of the materials are closely related to the composition. It is essential to integrate the multivalent element into the layered‐oxide lattice to achieve high proton conductivity, as the proton conduction is a coherent effect between the reduction of the multivalent element, such as cobalt, and the insertion of protons.