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Publication type: Conference paper
Type of review: Peer review (abstract)
Title: Composite conductivity of MIEC-based SOFC anodes : implications for microstructure optimization
Authors: Marmet, Philip
Hocker, Thomas
Boiger, Gernot K.
Grolig, Jan G.
Bausinger, Holger
Mai, Andreas
Fingerle, Mathias
Reeb, Sarah
Brader, Joseph M.
Holzer, Lorenz
et. al: No
DOI: 10.21256/zhaw-26055
Conference details: 15th European SOFC & SOE Forum 2022, Lucerne, Switzerland, 5-8 July 2022
Issue Date: 5-Jul-2022
Publisher / Ed. Institution: ZHAW Zürcher Hochschule für Angewandte Wissenschaften
Publisher / Ed. Institution: Winterthur
Language: English
Subjects: EFCF2022; SOFC; CGO; Titanates; Digital microstructure design; Stochastic microstructure digital twin
Subject (DDC): 621.3: Electrical, communications, control engineering
Abstract: Fully ceramic anodes such as LSTN-CGO offer some specific advantages compared to conventional cermet anodes. Ceria- and titanate-based phases are both mixed ionic and electronic conductors (MIEC), which leads to very different reaction mechanisms and associated requirements for the microstructure design compared to e.g. Ni-YSZ. Due to the MIEC-property of both solid phases, the transports of neither the electrons nor the oxygen ions are limited to a single phase. As a consequence, composite MIEC electrodes reveal a remarkable property that can be described as ‘composite conductivity’ (for electrons as well as for ions), which is much higher than the (hypothetical) single phase conductivities of the same microstructure. In composite MIEC anodes, the charge carriers can reach the reaction sites even when the volume fraction of one MIEC phase is below the percolation threshold, because the missing contiguity is automatically bridged by the second MIEC phase. The MIEC properties thus open a much larger design space for microstructure optimization of composite electrodes. In this contribution, the composite conductivities of MIEC-based anodes are systematically investigated based on virtual materials testing and stochastic modeling. For this purpose, a large number of 3D microstructures, representing systematic compositional variations of composite anodes, is created by microstructure modeling. The underlying stochastic model is fitted to experimental data from FIB-SEM tomography. For the fitting of the stochastic model, digital twins of the tomography data are created using the methodology of gaussian random fields. By interpolation between and beyond the digital twin compositions, the stochastic model then allows to create numerous virtual 3D microstructures with different compositions, but with realistic properties. The effect of microstructure variation on the composite conductivity is then determined with transport simulations for each 3D microstructure. Furthermore, the corresponding microstructure effects on the cell-performance are determined with a Multiphysics model that describes the anode reaction mechanism. Especially the impact of the composite conductivities on the cell performance is studied in detail. Finally, microstructure design regions are discussed and compared for three different anode materials systems: titanate-CGO (with composite conductivities), Ni-YSZ (with single-phase conductivities), Ni-CGO (with single-phase ionic and composite electronic conductivities).
Fulltext version: Published version
License (according to publishing contract): Licence according to publishing contract
Departement: School of Engineering
Organisational Unit: Institute of Computational Physics (ICP)
Published as part of the ZHAW project: Versatile oxide fuel cell microstructures employing WGS active titanate anode current collectors compatible to ferritic stainless steel interconnects (VOLTA)
GeoCloud – Simulation Software for Cloud-based Digital Microstructure Design of New Fuel Cell Materials
Appears in collections:Publikationen School of Engineering

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