Combinatorial Development of LSF Based Cathode Material for IT-SOFC

The primary challenges for the commercialization of the technology are considered to be costs and durability. To accommodate this, research is pushing towards lower cell operation temperature (intermediate temperature SOFC, IT-SOFC) in the range of 500–700 0C [1,2]. The lower temperatures involve advantages such as wider and cheaper choice of materials (e.g. metals), increased material durability, and increased system stability. The progress in this field is, inevitably associated with a continuous search for novel cathode and anode materials having superior electrocatalytic activity in the intermediate-temperature range. These developments have also a key importance for other solid-state electrochemical devices, such as electrolyzer of carbon dioxide and water vapor [3]. The fact that oxygen reduction rate is faster at the interface ,necessitates cathodes to be considered as composite. In this context, the traditional method is to mix cathode with electrolyte. This approach allows oxygen to be reduced at the interface and transported at the same time. Mixing cathode with electrolyte allows us to adjust the thermal expansion coefficient of the cathode. Another benefit of this approach is better bonding between the cathode and the electrolyte. Experimental The aim is to find the best cathode composition as a mixture of (La0.5Sr0.5)MnO3-δ (LSM), (La0.8Sr0.2)FeO3-δ (LSF) and (Zr10.92Sc0.08)O2- δ (8ScSZ) for IT-SOFC. In this study LSM, LSF and ScSZ targets were sputtered on both sides of Zr10.92Sc0.08 O2- δ electrolyte to form symmetric cells. We obtained 21 cells at the same time each with a different cathode composition. Geometry of targets and substrate is given in figure 1. Figure 1.Target and substrate geometries The produced cells were structurally characterized with XRD and SEM. Electrochemical performance of cells were determined using electrochemical impedance spectroscopy. The target working temperature is 600 0C and area specific resistance is maximum 0.15 ohm.cm2. References [1] R. Knibbe, J. Hjelm, M. Menon, N. Pryds, M. Søgaard, H.J. Wang, K. Neufeld, J. Am. Ceram. Soc. 93 (9) (2010) 2877–2883. [2] M.C. Tucker, J. Power Sources 195 (15) (2010) 4570–4582. [3] Tsipis, E. V., & Kharton, V. V. (2007). Journal of Solid State Electrochemistry,12(9), 1039-1060. Acknowledgement The support was provided by the Scientific and Technological Research Council of Turkey (TUBITAK) with a project number 217M628, which the authors gratefully acknowledge. Figure 1