Title: LST-CGO anodes : deconvolution of impedance spectra and relationship with composition and microstructure
Authors : Burnat, Dariusz
Holzer, Lorenz
Nurk, Gunnar
Heel, Andre
Published in : Proceedings of 13th European SOFC & SOE Forum 2018
Conference details: 13th European SOFC & SOE Forum 2018, Lucerne, 3-6 July 2018
Issue Date: 4-Jul-2018
License (according to publishing contract) : Not specified
Type of review: Not specified
Language : English
Subject (DDC) : 621.3: Electrical engineering and electronics
Abstract: Ni-free anodes in SOFC and SOEC that can withstand severe conditions and provide high performances, which is of great practical and scientific interest. Lanthanum doped strontium titanates (LST) are among the most interesting alternatives to state of the are Ni-YSZ due to their excellent redox stability [1] low reactivity with other fuel cell components [2] and good electronic conductivity. Insufficient ionic conductivity of LST is only one of few drawbacks of this class of materials and can be mitigated through fabrication and optimization of composite electrodes containing LST and good ionic conductor (e.g. CGO or YSZ). In this study the electrochemical performance of ceramic (Ni-free) SOFC anodes, consisting of A-site deficient La0.2Sr0.7TiO3-d (LST) perovskite and Gd0.1Ce0.9O1.95-d (CGO), was thoroughly investigated. Microstructures and compositions were systematically modified to gain information about the microstructural impact on electrochemical performance. The highest impedances are measured at low frequencies, which in contrast to the literature cannot be linked with gas concentration impedance. The low frequency process (ca. ~1 Hz) was attributed to the chemical capacitance. The EIS and advanced microstructure quantification methodology point out that the chemical capacitance correlates inversely with the available surface area of CGO. The influence of CGO surface reactions, such as hydrogen adsorption, which represent the kinetic limitation for the dominant anode process at 1 Hz region and for the associated chemical capacitance, is discussed. The impact of 30 isothermal redox cycles on degradation and the anode performance is presented.
Further description : B0607
Departement: School of Engineering
Organisational Unit: Institute of Computational Physics (ICP)
Institute of Materials and Process Engineering (IMPE)
Publication type: Conference Paper
URI: https://digitalcollection.zhaw.ch/handle/11475/8934
Appears in Collections:Publikationen School of Engineering

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