Improvement of electrochemical performance in alkaline fuel cell by hydroxide ion conducting Ni–Al layered double hydroxide

Abstract

This paper reports on the application of hydroxide ion conducting layered double hydroxides (LDHs) to the catalyst layer in an alkaline fuel cell for the improvement of the oxygen reduction reaction (ORR) at the triple phase boundary (TPB) in the catalyst layer. Ni–Al LDH intercalated with CO32− (Ni–Al CO32− LDH) and Mg–Al CO32− LDH were used in this study. Ni–Al CO32− LDH showed higher ionic conductivity than Mg–Al CO32− LDH under R.H. of 80%. The catalyst layers with and without hydroxide ion conducting LDHs was prepared, and a half-cell using the prepared catalyst layers was fabricated. The addition of LDHs to the catalyst layer increased the reduction current for ORR, indicating that hydroxide ion conducting LDHs introduced OH− conducting paths and increased TPB region within the catalyst layer. Above all, the addition of Ni–Al CO32− LDH to the catalyst layer more effectively increased the reduction current for ORR than the addition of Mg–Al CO32− LDH. The performance of the alkaline-type direct ethanol fuel cell was also improved. These experimental results indicate that high hydroxide ion conducting Ni–Al CO32− LDH effectively increased TPB region within the catalyst layer.