High performance praseodymium nickelate oxide cathode for low temperature solid oxide fuel cell

The praseodymium nickelate oxide Pr₂NiO_4+δ, a mixed conducting oxide with the K₂NiF₄-type structure, was evaluated as cathode for low temperature solid oxide fuel cells (T = 873 K). The electrochemical performance of the cathode has been improved by optimization of the microstructure of the porous cathode combined with the use of a ceria barrier layer in between the cathode and zirconia electrolyte. Both low polarization and ohmic resistances were obtained using Pr₂NiO_4+δ-powders with a median particle size of 0.4 μm, and sintering the screen printed layer at a sintering temperature of about 1353 K for 1 h. These manufacturing conditions resulted in a cathode microstructure with well established connections between the cathode particles and good adhesion of the cathode on the electrolyte. Full-sized anode supported cells have been manufactured using the same process conditions for the Pr₂NiO_4+δ cathode and tested. The best results were obtained when using a dense Ce_0.8Gd_0.2O_1.9 (20CGO) barrier layer. While a complete optimization of the cell preparation has not yet been achieved, the electrochemical performances of anode supported cells with Pr₂NiO_4+δ are higher than those with the well known state-of-the-art La_0.6Sr_0.4Fe_0.8Co_0.2O_3−δ (LSFC) material.