Compatibility of Praseodymium Nickelates with Various Cathode Current Collectors and Electrolytes

Nickelates, e.g. La2NiO4 and Pr2NiO4, have been of particular interest in the development of new generation oxygen electrodes for solid oxide fuel cells. The primary motivation for the utilization of nickelates is largely due to their resident oxygen interstitials, which are very mobile defects and thus capable of exchanging with ambient air at a substantially high rate. Indeed, nickelates exhibit superior electrochemical properties for oxygen reduction. Equally, if not more important research, is to investigate the stability of these electrodes with respect to time, temperature and compatibility with other constituents in a cell. In this paper, the high performance Pr2NiO4 cathode is reported together with its compatibility with various cathode current collectors and electrolytes. It was observed that at 750oC Pr2NiO4 is compatible with LSC or LSM current collectors up to 500 hours, but there exists an interdiffusion between Pr2NiO4 and ceria layer. Even with the presence of interdiffusion, the degradation rate at 0.8 V over 1000 hours was marginal, ~ 3% per 1000 hours.