Electrochemical investigation and chemical compatibility between Ln2NiO4+s cathode materials and BaCe0.65Zr0.20Y0.15O3-d electrolyte for PCFC applications

Protonic Ceramic Fuel Cells (PCFCs) have recently gained interest due to their advantages on decreasing solid oxide fuel cell operating temperatures. In this respect, proton conducting electrolyte materials based on Y-doped BaCe1-xZrxO3-? with x between 0.2 and 0.3 have been intensively investigated, because of their high proton conductivity and chemical stability at 500 to 800°C also in CO2-containing atmosphere, as in the case of hydrocarbon fuelled SOFCs. [1-2] However, the development of proper cathode materials for PCFCs remains a challenge, since the high polarization at the cathode side is still a hindrance to their development. To this end, recent studies have highlighted the potential of layered materials based on Ruddlesden-Popper series (An+1BnO3n+1) for cathode applications. In particular n=1 members, notably those based on Ln2NiO4+? have to be underlined. [3, 4] In this work, aiming to investigate the possible use of these cathodes in new PCFC devices, electrochemical study and chemical compatibility between Ln2NiO4 (Ln = La, Nd, Pr) cathodes and BaCe0.65Zr0.20Y0.15O3??? electrolyte was checked at co-firing fabrication temperatures (1000-1200°C) and under PCFCs operating conditions. Electrochemical measurements performed on half cells will be presented in order to characterize the electrocatalytic activity of rare earth nickelates associated to BCZY electrolyte. Rate determining steps of the oxygen reduction reaction (ORR) were determined from electrochemical measurements and it was shown that proton is involved in the ORR for the materials showing the best electrochemical performances. Finally, single PCFC cells were developed and I-V polarization curves have been measured. References [1] T.Norby, Solid State Ionics 125, 1 (1999). [2] S. Barison, M. Battagliarin, T. Cavallin, S. Daolio, L. Doubova, M. Fabrizio, C. Mortalò, S. Boldrini, L. Malavasi, R. Gerbasi, J. Mater. Chem. 18, 5120 (2008). [3] J. Dailly, F. Mauvy, M. Marrony, M. Pouchard, J-C. Grenier, Journal of Solid State Electrochemistry 15, 245 (2011). [4] J. Dailly, S. Fourcade, A. Largeteau, F. Mauvy, J-C.Grenier, M. Marrony, Electrochimica Acta 55, 5847 (2010).