Preparation and performance of PrLaNiO4 and (La0.75Sr0.2Ba0.05)(0.175)Ce0.825O1.891 composite cathode material by solid state reaction for IT-SOFCs

Abstract

Pr2NiO4 is one of the compounds in the Ln(2)NiO(4) (Ln=Pr, La and Nd) group that exhibits the Ruddlesden-Poppor structure. The present research substituted this compound by lanthanum (La) to enhance chemical stability, because of the decomposition reaction of Pr2NiO4 for long-term operation. PrLaNiO4 powders were then synthesized using a solid state reaction method for the application of cathode materials in an intermediate temperature solid oxide fuel cell (IT-SOFC); these material properties were then examined by XRD, SEM, thermomechanical analysis, alternating current impedance spectroscopy, and electrochemical analysis. The crystallization of the as-prepared PrLaNiO4 was obtained after heat-treatment at 1200 degrees C for 6 h. Moreover, PrLaNiO4 cathode material demonstrated favorable chemical stability with the electrolyte of (La0.75Sr0.2Ba0.05)(0.175)Ce0.825O1.891 (LSBC) under 1200 degrees C for 6 h. The determined thermal expansion coefficient of PrLaNiO4 was 14.1 x 10(-6) K-1. Furthermore, to reduce their resistance the PrLaNiO4 powders were mixed with various wt% of LSBC. The maximal power density of PrLaNiO4-5 wt% LSBC is 606 mW/cm(2) operated at 800 degrees C in air, which also exhibited lower area-specific resistance of 0.202 Omega cm(2). The study concludes that the PrLaNiO4-5 wt% LSBC is a better choice than Pr2NiO4 in cathode material for IT-SOFCs.