Property Study of La_(2-x)Sr_xNiO_4 (x ≤ 0.8) For IT-SOFCs Cathode

摘要

Materials with Ruddlesden-Popper structure (A_2BO_4) such as La_2NiO_4 system have been identified as the new cathode materials for intermediate temperature solid oxide fuel cells (IT-SOFCs) as their coefficient of thermal expansion values match those of the currently used electrolytes. Moreover, such materials have shown mixed ionic and electronic conductivity desirable for cathodes. The low electronic conductivity of La_2NiO_4 remains a challenge. To improve this property, investigations on La_(2-x)Sr_xNiO_(4+δ) (x = 0, 0.4, and 0.8) prepared via sol-gel and solid state reaction processes were carried out in this study. Effects of Sr substitution on A sites on physical and electrical properties of the compound were investigated and compared. A simple preparation sol-gel process, carried out at room temperature and using water as solvent for the synthesis of La_(2-x)Sr_xNiO_(4+δ), was successfully developed. The solgel synthesis method yielded more homogenous samples with higher conductivity compared to those synthesized via the solid state reaction method. Conductivity as high as 160 S/cm at 500°C was observed for La_(1.2)Sr_(0.8)NiO_(4+δ) synthesized via the sol-gel process.