Termal plazma ile orta sıcaklık katı oksit yakıt pilleri için LSC-113/LSC-214 kompozit katod üretimi.

The current study follows the previous work in which a superior performance was obtained in the composite cathode (La0.8Sr0.2)CoO3 (LSC-113) / (La0.5Sr0.5)2CoO4 (LSC-214) where the cathode was amorphous/nanocrystalline as a result of cosputtering of the respective oxides. In the present work, cathodes of similar compositions were produced via thermal plasma and electrochemically characterized by impedance spectroscopy. The study has shown that nanopowders of LSC113/LSC-214 can be synthesized via thermal plasma by feeding La(NO3)3.6H2O, Sr(NO3)2, Co(NO3)2.6H2O precursor solution. Nano powders obtained with RF thermal plasma with 25 kW were 58 nm in size and the Rietveld refined XRD pattern showed that the powder was a composite of LSC-113:LSC-214=0.3:0.7. The potential of the powder as cathode material was tested on a symmetric cell where the powder was applied either side of the electrolyte (GDC) and tested with impedance spectroscopy. Measurement conducted over a wide range of temperatures between 350-700oC. This has shown that the area specific resistance values of the cathodes made with synthesized powders were similar to those of co-sputtered cathodes. An ASR value of 0.15 Ω.cm2 can be obtained in the current cathodes at temperatures as low as 665oC. A synthesis of LSC-113: LSC-214= 0.5:0.5 was recommended where the operating temperature of the cathode could be reduced to temperatures less than 600oC.Thesis (M.S.) -- Graduate School of Natural and Applied Sciences. Metallurgical and Materials Engineering

SYNTHESIS OF DUAL PHASE CATHODE FOR IT SOFCs VIA THERMAL PLASMA

The combinatorial approach is particularly suitable for identification of suitable cathode materials. This involves a simultaneous deposition of thin film cathodes each with a different composition in a single experiment. The composition and microstructure of cathode materials has a large impact on the performance of solid oxide fuel cells (SOFCs). A main goal in SOFC research is the development of cathodes with a sufficiently low electrochemical resistance (- 0.15 Q.cm2) at operating temperatures significantly below 800°C. Focus has been shifted to particularly mixed conducting perovskites of the La I -xSncCo03-8 (LSC), Lal–xSniMnO3AZ (LSM), LaxSrl–xCoyFel–y03-8 (LSCF) family [1]. Since, Cnunl in et al.[2] and Sase et al. [3] exhibit improved electrochemical performance with hetero-structures [4]. Oxygen surface exchange was found to be enhanced at the heterointerface of LSC214/LSC113 [3]. It was recently shown that the sputter deposited (La0.8Sr0.2) Co03 (LSC-113) - (La0.5Sr0.5)2Co04 (LSC-214) dual phase cathode yield the best performance where the mixture had an amorphous-like structure [5]. In this study a composite cathodes LSC113- LSC214 and LSF-LSM were synthesized via thermal plasma using a large flow rate of quenching gas yielding non-equilibrium cathode powder. The purpose is to see if similar performance improvement could be obtained with plasma synthesized composite powders. The powders were screen printed onto suitable electrolytes and were characterized based on EIS responses using a symmetric cell under air. The typical EIS response at 500°C is given in Fig

Synthesis of Dual Oxide Cathode for IT-SOFCs via Th ermal Plasma

The composition and microstructure of cathode materials has a large impact on the performance of solid oxide fuel cells (SOFCs). It was recently shown that the sputter deposited (La0.8Sr0.2) CoO3 (LSC-113) - (La0.5Sr0.5)2CoO4 (LSC-214) dual phase cathode yield the best performance where the mixture had an amorphous-like structure. In this study a composite cathode of LSC-113: LSC-214 was synthesized via thermal plasma using a large flow rate of quenching gas yielding non-equilibrium cathode powder. The purpose is to see if similar performance improvement could be obtained with plasma synthesized powder. Powder obtained were then screen printed onto the gadolinium doped ceria (Gd0.1Ce0.9O1.95) electrolytes and were characterized based on EIS responses using a symmetric cell under air