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Issue 17, 2019
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In operando monitoring of reaction-diffusion streamlines and uncovering of electrochemo-structural interactions in electrodes

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Abstract

An open question for interpretation of impedance spectra of electrochemical cells is how to decouple the electrochemo-structural interactions. Reduced-dimensional models, such as equivalent circuits, face challenges in capturing the impacts of inhomogeneities (e.g. roughness and constriction effects) in three-dimensional microstructures, where mean-field assumption breaks down. Here we report a new method to analyze the impedance spectra of the reaction-diffusion process in an electrode based on a distribution of reaction-diffusion streamlines (DRDS) connected parallelly with different lengths (representing the roughness effects) and shapes (representing the constriction effects). Demonstrations on (La,Sr)(Co,Fe)O3−δ electrodes show that the DRDS method can explicitly capture the geometric inhomogeneities and the multiple rate-determining steps in the multi-scale features of the electrode microstructure. Furthermore, the kinetic parameters for the reaction-diffusion process can be extracted accurately from the DRDS analysis, and ‘direct three-phase-boundary reactions’, a well-known open hypothesis in solid oxide cells, are monitored clearly by using the DRDS pattern. This method is generally applicable to many electrochemical systems involving a reaction-diffusion process in the electrode.

Graphical abstract: In operando monitoring of reaction-diffusion streamlines and uncovering of electrochemo-structural interactions in electrodes

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Publication details

The article was received on 17 Feb 2019, accepted on 29 Mar 2019 and first published on 01 Apr 2019


Article type: Paper
DOI: 10.1039/C9TA01784D
Citation: J. Mater. Chem. A, 2019,7, 10256-10263

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    In operando monitoring of reaction-diffusion streamlines and uncovering of electrochemo-structural interactions in electrodes

    Y. Zhang, F. Yan, J. Ma, M. Yan, M. Ni and C. Xia, J. Mater. Chem. A, 2019, 7, 10256
    DOI: 10.1039/C9TA01784D

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