Impedance Spectroscopy Analysis of Ni/YSZ Interfaces Prepared by Liquid Precursor Deposition

Tuesday, 26 May 2015: 16:40
Boulevard Room C (Hilton Chicago)
A. Buyukaksoy and V. Birss (University of Calgary)
The state-of-the-art material for SOFC anodes is a Ni-yttria-stabilized zirconia (Ni-YSZ) based cermet, due primarily to the excellent electrocatalytic activity of Ni towards H2oxidation. To design and construct Ni-YSZ anodes with maximum performance, it is important to understand the reaction mechanism at the Ni/YSZ interface. Therefore, model anode designs, in which dense Ni films were deposited on dense YSZ electrolytes in the form of regularly spaced strips, have been developed by multiple groups [1, 2] to control the Ni/YSZ interfacial length, with impedance spectroscopy (EIS) used to evaluate performance. However, a consensus has not been reached yet on the exact reaction steps and how they change with temperature. Charge transfer at the Ni/YSZ interface, hydrogen diffusion on Ni surface and hydrogen adsorption/desorption reaction, have all been suggested as the rate-limiting steps in the literature [1, 2]. Thus, a clear identification of the rate limiting step at the Ni/YSZ interface and its correlation with the Ni-YSZ composite anodes is still required.

In this work, solution precursor deposited Ni thin films were deposited on dense Zr oxide discs for comparison with Ni-YSZ composite anodes that were prepared by the infiltration of the Ni solution precursor into porous YSZ scaffolds. EIS analysis was carried out, and a transmission line model, which allows the separation of the porous YSZ scaffold ionic resistance and the Ni/YSZ interfacial impedance, was used to fit the impedance data. The dominant impedance arcs in the thin film Ni anodes and the Ni/YSZ interfacial impedance, extracted from the transmission line modelling of the Ni-YSZ composites, both exhibited an activation energy of ~1.3 eV. The same activation energy obtained for the Ni/YSZ interfacial impedance obtained from both Ni thin film anodes and infiltrated Ni-YSZ anodes validates the transmission line fitting approach while the obtained activation energy value of ~1.3 eV indicates that the charge transfer process occurring at the triple phase boundary is the rate determining reaction step in Ni-YSZ anodes.


The authors gratefully acknowledge the Eyes High PDF Program at the University of Calgary and Alberta Innovates – Technology Futures (AITF) for the support of AB, as well as the Natural Sciences and Engineering Research Council of Canada (NSERC) for the overall financial support of this work.


1. A. Bieberle, L. P. Meier and L. J. Gauckler,  J. Electrochem. Soc., 148 (2001) A646.

2. A. Utz, H. Stormer, D. Gerthsen, A. Weber, E and Ivers-Tiffee, Solid State Ionics, 192 (2011) 565.