Effect of La[sub 2]Zr[sub 2]O[sub 7] on Interfacial Resistance in Solid Oxide Fuel Cells

Abstract

The impact of La 2 Zr 2 O 7 ͑LZO͒ on interfacial resistance ͑R p ͒ at the La 0.78 Sr 0.20 MnO 3−␦ /yttria-stabilized zirconia interface was studied upon isothermal sintering at 1200°C for 2-25 h. Quantification of triple phase boundary length was performed by applying focused ion beam/scanning electron microscopy ͑FIB/SEM͒ serial-sectioning techniques and classical stereology. Electrochemical impedance spectroscopy was used to characterize the R p . The effect of LZO formation on microstructural models for R p was analyzed with respect to previous works that did not include this effect. LZO formation modifies the TPB length, rapidly increases R p , and needs to be controlled in analytical microstructural R p models.

Factors that Influence Cation Segregation at the Surfaces of Perovskite Oxides

“…(25) The presence of La 2 Zr 2 O 7 at the electrode/electrolyte interface can be reasonably excluded because of the GDC layer between the electrode and electrolyte. (9,27) Changes in surface chemistry may affect the charge transfer reaction at the triple boundary region, causing degradation of ORR activity. Observed higher stability at elevated temperatures of A-site deficient LSM films demonstrates the correlation between the chemical stability and the electrode reactivity at elevated temperatures.…”

Simulation of sintering kinetics and microstructure evolution of composite solid oxide fuel cells electrodes

“…Two sets of literature data reported by Mitterdorfer and Gauckler [34] and Chen et al [35] are used to scale kMCS and kT/J with the realistic sintering time and temperature, as well as to validate the kMC model. These two studies both experimentally investigated the sintering kinetics and the variation of TPB length for porous LSM electrodes on YSZ electrolytes under different conditions.…”

“…For example, after 4 h sintering at 1200 C, a thinly layered La 2 Zr 2 O 7 is formed with a thickness of w45 nm. The thickness is increased to w75 nm after 20 h sintering [35]. Since the resolution of the present kMC model is 50 nm, which is insufficient to accurately capture this phenomenon, the reaction between LSM and YSZ is not i n t e r n a t i o n a l j o u r n a l o f h y d r o g e n e n e r g y 3 7 ( 2 0 1 2 ) 3 3 9 2 e3 4 0 2 considered.…”

“…Because the interaction energy cannot be determined, the dimensionless parameter, kT/J is used as the model temperature. Two sets of literature data [34,35] are used to scale the kMCS and kT/J for LSMeYSZ systems in the section of results and discussion.…”

Performance regeneration in lanthanum strontium manganite cathode during exposure to H₂O and CO₂ containing ambient air atmospheres

“…7) Extensive studies have shown that the cell performance degradation is caused by oxide segregation, 8),9) chromium deposition, 10) material deterioration, 11) and La 2 Zr 2 O 7 formation at LSM/YSZ interface. 12), 13) We have recently reported the stability of LSM cathode in humidified air 14) and carbon dioxide containing air. 15) In humidified air, SrO segregation on LSM cathode was enhanced by water content, electric bias, and low oxygen partial pressure; 14) in CO 2 -containing air, SrO converts to SrCO 3 at the LSM surface, resulting in initial performance degradation.…”