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On the Bulk Transport Process and Its Impact on the Electrode Behavior of Mixed Conducting Electrodes for SOFCs

Abstract

The surface reaction and bulk transport processes represent two pillars in the kinetics studies of SOFCs electrodes. The driving force of ion transport process in the mixed ion-electron conductor (MIEC) electrodes is recapitulated. Qualitative and quantitative analyses are conducted on the so-called “bulk diffusion” process, along with experimental verification through (LaSr)(CoFe)O3-δ cathode. It is proven that an electrical field will be present inside the MIEC electrode, which drives the motion of ions along with the concentration gradient. Under steady state, distributions of ce, cv, ϕ etc. are obtained. The impact of this electrical field on the electrode kinetics and stability is discussed. It is revealed that: (a) The equivalent PO2 at the interface calculated according to the overpotential and the Nernst equation could overestimate the stability concern. (b) From the viewpoint of the bulk pathway, polarization is not necessarily a beneficial factor, which could open up, or shut down the bulk pathway depending on the ionic defect type. (c) The electrical field also can drive the motion of cations, leading to composition evolution near the interface in those materials with relatively rich cation vacancies.

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Publication details

The article was received on 18 Jun 2017, accepted on 10 Aug 2017 and first published on 11 Aug 2017


Article type: Paper
DOI: 10.1039/C7CP04103A
Citation: Phys. Chem. Chem. Phys., 2017, Accepted Manuscript
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    On the Bulk Transport Process and Its Impact on the Electrode Behavior of Mixed Conducting Electrodes for SOFCs

    W. Li, B. Guan, T. Yang, N. Zhang, X. Zhang and X. Liu, Phys. Chem. Chem. Phys., 2017, Accepted Manuscript , DOI: 10.1039/C7CP04103A

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