Lowering the Impedance of Lanthanum Strontium Manganite-Based Electrodes with Lanthanum Oxychloride and Lanthanum Scavenging Chloride Salts

The impact of infiltrating chloride salts on the electrochemical behavior of lanthanum strontium manganite-yttria stabilized zirconia (LSM-YSZ) cathodes was investigated under solid oxide fuel cell operation. Infiltrating a lanthanum chloride solution resulted in the formation of a lanthanum oxychloride (LaOCl) phase. A LaOCl phase also formed by infiltrating an ammonium chloride solution; however, lanthanum was scavenged from the LSM phase to form LaOCl. The third infiltrating solution, a combination of zirconium chloride and yttrium nitrate, formed LaOCl by scavenging lanthanum from LSM and produced YSZ nanoparticles. Electrochemical impedance spectroscopy results suggest that LaOCl improves oxygen adsorption kinetics compared to a baseline LSM-YSZ cathode, reducing the low frequency impedance by 30%. In addition, scavenging lanthanum from LSM improved oxygen ion diffusion polarization as indicated by the observed 40% reduction in high frequency impedance and improved serial ohmic resistance by 19%. Finally, YSZ nanoparticles further reduced the high frequency impedance and ohmic resistance by 45% and 23%, respectively. The findings reveal new strategies for lowering the impedance of LSM-YSZ cathodes.