About this Abstract |
Meeting |
2021 TMS Annual Meeting & Exhibition
|
Symposium
|
Advanced Materials for Energy Conversion and Storage VII
|
Presentation Title |
Three-dimensional Simulation of Electrochemical Impedance in Solid Oxide Fuel Cell (SOFC) Cathodes and Its Application in Cathode Characterization |
Author(s) |
Vishwas Goel, Dalton Cox, Scott A Barnett, Katsuyo Thornton |
On-Site Speaker (Planned) |
Vishwas Goel |
Abstract Scope |
In this work, we propose the application of electrochemical impedance spectroscopy (EIS) in characterizing the microstructure of mixed ion-electron conducting (MIEC) cathodes of solid oxide fuel cells (SOFC). In particular, we show that the EIS data can be used for determining the effective tortuosity of cathodes. We obtain the impedance response of a SOFC cathode, with an experimentally determined three-dimensional (3D) microstructure, by solving the mass conservation equation for the oxygen vacancies under the conditions of an AC load across the cathode’s thickness and surface reaction at the pore/solid interface. Our simulation results provide two key insights. First, there is a need to modify the Adler-Lane-Steele model, which is widely used for fitting the impedance behavior of a MIEC cathode, to account for the difference in the oscillation amplitudes of the oxygen vacancy concentration at the pore/solid interface and within the solid bulk. Second, the effective tortuosity is dependent on the frequency of the applied AC load as well as the material properties (reaction rate constant and bulk diffusivity), and thus the prevalent practice of treating the tortuosity as a constant for a given microstructure should be revised. |
Proceedings Inclusion? |
Planned: |
Keywords |
Computational Materials Science & Engineering, |