A fast ceramic mixed OH-/H+ ionic conductor for low temperature fuel cells

Abstract

Abstract OH- and H+ ionic conductors are important electrolyte materials for electrochemical devices such as fuel cells. The high cost of the best low temperature H+ ionic conductor, Nafion membrane, and the poor chemical compatibility with CO2 in air of alkaline membrane based on quaternary ammonium groups have seriously affected the large-scale application of low temperature fuel cells. Here we show the discovery of a fast ceramic mixed OH-/H+ conductor, perovskite oxide SrZr0.8Y0.2O3-δ, which exhibits a high ionic conductivity of approximately 0.01 S cm-1 at 90°C when measured in water and wet air, sufficient to be used as electrolyte for low temperature fuel cells. The ionic conductivity is stable in wet air during the measured 130 hours. The ionic conduction was also demonstrated by near ambient temperature solid oxide fuel cells (NAT-SOFCs). This opens a window on discovering new ionic conducting materials for low temperature fuel cells.