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Thermal plasma synthesis of LSC-113/LSC-214 composite cathode for IT-SOFCS

Aysal, Havva Eda
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.