Modeling the impedance response of mixed-conducting thin film electrodes

Abstract

In this paper a novel numerical impedance model is developed for mixed-conducting thin films working as electrodes for solid oxide fuel cells. The relative importance of interfaces is considered by incorporating double layer contributions at the film/gas boundary. Simulations are performed on a model system, namely doped ceria, in a symmetric cell configuration using geometrically well-defined patterned metal current collectors. Results reveal that experimentally consistent bulk impedances and surface capacitances can be extracted using the model. The impedance response depends strongly on the pattern spacing of the current collector, and is attributed to the electronic in-plane drift-diffusion as well as to the interplay between the surface reaction resistance and the electronic/ionic bulk drift-diffusion resistance.

A detailed look into hydrogen electrochemical oxidation on ceria anodes

“…The individual contribution of each resistive step to the total electrode resistance M A N U S C R I P T is given in Table 3. Inline with the previous studies [13,12], the resistance caused by the ionic and the electronic transport is significantly smaller than the resistance caused by the surface kinetics. This implies that the diffusion process is fast enough to be unlikely to control the cell response at these conditions.…”

“…Since the resistance caused by the bulk transport is insignificant compared to the resistance caused by the reaction kinetics, rate limitations are globally attributed to the surface kinetics that is in line with the previous studies [13,12,30]. The kinetics of elementary steps in the proposed reaction scheme allow us to identify the rate-determining elementary step, which is performed by a sensitivity analysis.…”

“…The impedance of a thin-film ceria anode, corresponding to what we measure experimentally, can then be categorized into: 1) the drift-diffusion resistance associated with the transport of electrons between the current collector and the reaction sites at 2PB (commonly termed as the current collector spacing), and 2) the surface reaction resistance associated with the charge transfer process at the 2PB. Chen et al [12] and Ciucci et al [13] studied these two processes in a reducing environment (H 2 − H 2 O − Ar) at 550-650 o C using the Nernst-Planck-Poisson (NPP) model. The authors reported that the drift-diffusion resistance is negligibly small if the spacing is less than 10 µm, indicating the important role of the reaction resistance.…”

Comparison of Electrochemical Properties of La0.6Sr0.4FeO3-δThin Film Electrodes: Oxidizing vs. Reducing Conditions

“…39 Those studies revealed that such model type experiments based on MIEC thin films and current collectors are highly valuable in order to better understand properties and limitations of mixed conducting SOFC anodes /SOEC cathodes. However, mechanistic studies on LSF thin film electrodes in H 2 /H 2 O are rare, one study reports its performance in a SOEC cell.…”

Computer assisted corrosion analysis of hydroxyapatite coated CoCrMo biomedical alloys

“…COMSOL Multiphysics software, a complex simulation program, can be applied to model electrochemical analysis [16]. There are many successful modeling studies reported in recent years with COMSOL [17,18]. However, there are few COMSOL modeling studies for electrodeposition of coatings [19,20].…”