Molten salt synthesis of La_0.8Sr_0.2MnO₃ powders for SOFC cathode electrode

Abstract

For La_0.8Sr_0.2MnO₃ (LSM) perovskite, used as the cathode material for solid oxide fuel cells (SOFC), it is known that the formation of a triple-phase-boundary is restrained due to the formation of a second phase at the YSZ/electrode interface at high temperature. To decrease the 2^nd phase, lowering the sintering temperature has been used. LSM powder was synthesized by molten salt synthesis method to control its particle size, shape, and agglomeration. We have characterized the phase formation, particle size, shape, and sintering behavior of LSM in the synthesis using the variation of KCl, LiCl, KF and its mixed salts as raw materials. In the case of KCl and KCl-KF salts, the particle size and shape of the LSM was well controlled and synthesized. However, in the case of LiCl and KCl-LiCl salts, LiMnO_x as 2^nd phase and LSM were synthesized simultaneously. In the case of the mixed salt of KCl-KF, the growth mechanism of the LSM particle was changed from ‘diffusion-controlled’ to ‘reaction-controlled’ according to the amount of mixed salt. The sintering temperature can be decreased below 1000 °C by using the synthesized LSM powder.