Electrochemical Impedance Analysis of Symmetrical Ni/Gadolinium-Doped Ceria (CGO10) Electrodes in Electrolyte-Supported Solid Oxide Cells. Issue 13 (1st January 2019)

• Record Type: Journal Article
• Authors: Riegraf, Matthias; Costa, Rémi; Schiller, Günter; Friedrich, K. Andreas; Dierickx, Sebastian; Weber, André
• Is Part Of: Journal of the Electrochemical Society. Volume 166:Issue 13(2019)
• Page Start: F865
• Page End: F872
• Publication Date: 2019-01-01
• Subjects: Electrode Kinetics -- Fuel Cells -- Fuel Cells - Solid oxide -- Ni/GDC -- solid oxide electrolysis cell (SOEC) -- Solid oxide fuel cell (SOFC); Electrochemistry -- Periodicals; 541.3705
• DOI: 10.1149/2.0051913jes
• Languages: English
• ISSNs: 0013-4651

Abstract

Abstract : One of the most powerful tools in solid oxide cell (SOC) characterization is electrochemical impedance spectroscopy, which can unfold important insights into SOC performance characteristics and degradation behavior. To obtain a better understanding of the electrochemical behavior of Ni/CGO fuel electrodes, this work presents a comprehensive investigation of state-of-the-art Ni/CGO10-based electrolyte-supported cells. Commercial Ni/CGO10|CGO10|3YSZ|CGO10|Ni/CGO10 symmetrical cells were characterized between 550–975°C at p H2 = 0.8 bar and p H2 O = 0.2 bar, and for different H2 /H2 O gas mixtures at 550°C. (i) Small electrode area, (ii) thin electrodes and (iii) large gas flow rates were used to minimize mass transport contributions. Based on distribution of relaxation times (DRT) analysis an equivalent circuit model was derived. Electrode process contributions on Ni/CGO were determined by means of a complex non-linear least square fit of the equivalent circuit model to the experimental data. One low frequency process at 0.1–1 Hz and one middle frequency process at 10–100 Hz were identified and correlated to a surface and a bulk process, respectively. Values for the apparent activation energy barriers and reaction orders with respect to steam and hydrogen content were determined.