Investigation of the Characteristics of Materials with the Ruddlesden-Popper Structure for Solid Oxide Fuel Cells

This article presents the results of a study of the characteristics of materials based on lanthanum nickelate La2Ni1-xCoxO4+δ (0≤x≤0.3) and Pr2NiO4+δ. Their crystal structure and interaction with YSZ and GDC electrolyte materials at 900 °C are analyzed. The thermal expansion coefficients are determined and the temperature dependences of the conductivities are studied. The polarization resistance of these materials in contact with the electrolyte material YSZ is also measured. As a result of the study, the following cathode materials were investigated: La2Ni1-xCoxO4 (0≤ x ≤0.3), Pr2NiO4. In this case, the influence of low concentrations of Co on the characteristics of lanthanum nickelate was studied for the first time. Materials based on lanthanum nickelate and praseodymium nickelate were characterized by a structure of the K2NiF4 type (RuddlesdenPopper phases) with rhombic symmetry. A study of the thermal expansion of cathode materials showed that all the studied materials are characterized by higher CTEs than YSZ and GDC electrolytes. Based on the studies performed, cathode materials were chosen for the formation of composites with GDC electrolyte: La2NiO4, La2Ni0.8Co0.2O4, Pr2NiO4. A study of the sintering kinetics and CTE of composites showed that their thermal characteristics are much closer to those of electrolytes than those of pure cathode materials.