Co-infiltrating Pr_(0.6)Sr_(0.4)FeO_3-Ce_(1-x)Pr_xO_2(x=0.1, 0.3, 0.5, 0.7, 0.9) mixed oxides into the La_(0.9)Sr_(0.1)Ga_(0.8)Mg_(0.2)O_3 skeleton for use as low temperature solid oxide fuel cell cathodes

摘要

Here, first time, Pr_(0.6)Sr_(0.4)FeO_3-Ce_(1-x)Pr_xO_2 (x=0.1, 0.3, 0.5, 0.7, 0.9) dual-phase composites are co-infiltrated into the porous La_(0.9)Sr_(0.1)Ga_(0.8)Mg_(0.2)O_3 (LSGM) skeletons to form composite cathodes and are used for low temperature solid oxide fuel cell (SOFC). By optimizing mass ratios of Pr_(0.6)Sr_(0.4)FeO_3/Ce_(1-x)Pr_xO_2 and doping contents of Pr in the Pr_(0.6)Sr_(0.4)FeO_3-Ce_(1-x)Pr_xO_2 composites, the lowest polarization resistance (Rp) recorded at 550℃ is achieved as 0.246Ωcm~2 for the 50wt%Pr_(0.6)Sr_(0.4)FeO_3-50wt% Ce_(0.1)Pr_(0.9)O_2-LSGM composite cathode. Reduction of both chemical resistance and charge transfer resistance are proved to be responsible for the performance improvement. Thermal cycling test reveals a performance degradation of only 4.6% for the 50wt%Pr_(0.6)Sr_(0.4)FeO_3-50wt% Ce_(0.1)Pr_(0.9)O_2-LSGM composite cathode after five thermal cycles, thereby showing a good thermal expansion match between the 50wt%Pr_(0.6)Sr_(0.4)FeO_3-50wt%Ce_(0.1)Pr_(0.9)O_2 composite and the LSGM skeleton. A functional fuel cell with infiltrated Ni/Ce_(0.8)Sm_(0.2)O_2 (Ni/SDC) as anode and infiltrated 50wt%PSF-50wt% Ce_(0.9)Pr_(0.1)O_2 as cathode shows the maximum power densities of 1.172, 0.916, 0.519 and 0.196 Wcm~(-2) at 600, 550, 500 and 450℃, respectively. The cell operates at 550℃ with an almost constant current density of 1.087A/cm~2 at 0.7 V for 50 h, demonstrating good stability.