An Approach to the Development of LSCF/YSZ-SDCC Dual Composite Cathodes for Intermediate Temperature SOFCs

Abstract

A development of dual composite cathode, La_0.6Sr_0.4Co_0.2Fe_0.8O_3-d/Y₂ZrO₅-Sm_0.2Ce_0.8O_1.9 carbonate (LSCF/YSZ-SDCC) has been studied subjected on the composition of YSZ-SDCC composite. LSCF/YSZ-SDCC dual composite powders were produced through the high-energy ball milling method with a varied composition of YSZ-SDCC composite powder (50-70 wt.% YSZ: 50- 30 wt.% SDCC). The calcined LSCF/YSZ-SDCC powders were then successfully screen-printed on YSZ pellet to form a cathode thin film. A complete symmetrical cell was sintered for 90 minutes at 600°C. The crystalline phase, the carbonate bonding and the physical morphologies of the YSZ-SDCC composite cathode powders and the LSCF/YSZ-SDCC dual composite cathode powders were investigated. Furthermore, the microstructure and cathode thin film properties including electrochemical performances of LSCF/YSZ-SDCC were all evaluated. The various processes did not affect the carbonate bonding in any of the samples, however, phase identification analysis revealed the appearance of strontium carbonate (SrCO₃) as the secondary phase in the calcined LSCF/YSZ-SDCC powders. The microstructure study of the particles after milling demonstrates that the particles for all three YSZ-SDCC compositions do not agglomerate, with grain sizes of 244.97 40.66, 213.47 41.63, and 173.27 25.83 nm, respectively. Following that, all samples were electrochemically analyzed at temperatures of 700°C, 600°C, and 500°C. As compared to the other combinations, LSCF/YSZ-SDCC with 50:50 wt.% YSZ-SDCC compositions co-fired at 700°C showed the most favourable value in this study.