Electrochemical Behavior of Gel-Derived Lanthanum Calcium Cobalt Ferrite Cathode in Contact with LAMOX Electrolyte
Abstract:The electrochemical performance and structural features of (La1−yCay)(CoxFe1−x)O3 cathode prepared via a citrate acid gel route are studied when it is interfaced with the (La1.8Dy0.2)(Mo2−zWz)O9 electrolyte. The resistance and chemical capacitance of a low-frequency arc are extracted from the impedance results to evaluate its catalytic activity in oxygen reduction reaction (ORR). (La0.75Ca0.25)(Co0.8Fe0.2)O3 cathode exhibits the minimum area-specific resistance of 0.9 Ω cm2 and maximum capacitance of 5.7 mF/cm2 at 800°C among the compositions of x=0.1–0.9 and y=0.25. As the Co content increases, the decrease in resistance outweighs the increase in capacitance so that the product of resistance and capacitance (RC time constant) decreases. In contrast, when varying the Ca content of the A-site, the changes in resistance and the capacitance compensate each other; hence the RC time constant is virtually unchanged with respect to the calcium content. Thus, Co is a more influential element than Ca on the ORR catalytic activity. The pore structure study reveals a small amount of Mo diffuses from the electrolyte into the cathode, and its quantity is reduced when interfaced to an electrolyte of high W content.
Document Type: Research Article
Affiliations: 1: Department of Chemical Engineering, National Taiwan University of Science and Technology, Taipei 10607, Taiwan 2: Department of Chemical Engineering, National United University, Miaoli 36003, Taiwan
Publication date: July 1, 2008