La_xPr_4−xNi₃O_10−δ: Mixed A-Site Cation Higher-Order Ruddlesden-Popper Phase Materials as Intermediate-Temperature Solid Oxide Fuel Cell Cathodes

Systematic studies of the air electrode and full solid oxide fuel cell performance of La₃PrNi₃O_9.76, and La₂Pr₂Ni₃O_9.65 n = 3 Ruddlesden–Popper phases are reported. These phases were found to adopt orthorhombic symmetry with a decrease in lattice parameters on increasing Pr content, consistent with the solid solution series end members. From electrochemical impedance spectroscopy measurements of symmetrical cells, the electrodes were found to possess area specific resistances of 0.07 Ω cm² for the La₂Pr₂Ni₃O_9.65 cathode and 0.10 Ω cm² for the La₃PrNi₃O_9.76 cathode at 750 °C, representing a significant improvement on previously reported compositions. This significant improvement in performance is attributed to the optimisation of the electrode microstructure, introduction of an electrolyte interlayer and the resulting improved adhesion of the electrode layer. Following this development, the new electrode materials were tested for their single-cell performance, with the maximum power densities obtained for La₂Pr₂Ni₃O_9.65 and La₃PrNi₃O_9.76 being 390 mW cm⁻² and 400 mW cm⁻² at 800 °C, respectively. As these single-cell measurements were based on thick electrolytes, there is considerable scope to enhance over cell performance in future developments. View Full-Text