Abstract
Electrochemical Impedance Spectroscopy (EIS) is a frequently used method to characterize electrodes for Solid Oxide Fuel Cells (SOFC) or Electrolyzer Cells (SOEC). The porous microstructures, use of composite structures and sometimes extra functional layers in an electrode, result often in impedance spectra that are difficult to analyze. Transformation of the impedance into a distribution function of relaxation times (DFRT) is about to become a new standard in EIS analysis. This inversion to the τ-domain requires solving a Fredholm integral of the second kind, which is known as an ‘ill-posed inverse problem’. Hence the resulting DFRT's should not be trusted directly. In cases were impedance data can be modelled satisfactory with an Equivalent Circuit (EqC), built of known dispersion relations (e.g. (RQ), Gerischer, Finite Length Warburg) an analytic distribution function, G(τ), can be constructed. This can be compared with the inversion results obtained from Fourier Transform (FT), Tikhonov Regularization (TR) and multi-(RQ) CNLS fits (m(RQ)fit), thus allowing evaluation and validation of these methods This is illustrated in this contribution with four examples of SOFC cathodes with quite different properties. The results apply equally well to SOFC anodes (or SOEC cathodes).
| Original language | English |
|---|---|
| Pages (from-to) | 103-111 |
| Number of pages | 9 |
| Journal | Solid state ionics |
| Volume | 314 |
| Early online date | 7 Dec 2017 |
| DOIs | |
| Publication status | Published - 1 Jan 2018 |
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Keywords
- Electrochemical Impedance Spectroscopy (EIS)
- Electrodes
- Finite Length Warburg (FLW)
- Gerischer dispersion
- Distribution function of relaxation times (DFRT)
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Use of a distribution function of relaxation times (DFRT) in impedance analysis of SOFC electrodes. / Boukamp, Bernard A. (Corresponding Author); Rolle, Aurélie.
In: Solid state ionics, Vol. 314, 01.01.2018, p. 103-111.Research output: Contribution to journal › Article › Academic › peer-review
TY - JOUR
T1 - Use of a distribution function of relaxation times (DFRT) in impedance analysis of SOFC electrodes
AU - Boukamp, Bernard A.
AU - Rolle, Aurélie
PY - 2018/1/1
Y1 - 2018/1/1
N2 - Electrochemical Impedance Spectroscopy (EIS) is a frequently used method to characterize electrodes for Solid Oxide Fuel Cells (SOFC) or Electrolyzer Cells (SOEC). The porous microstructures, use of composite structures and sometimes extra functional layers in an electrode, result often in impedance spectra that are difficult to analyze. Transformation of the impedance into a distribution function of relaxation times (DFRT) is about to become a new standard in EIS analysis. This inversion to the τ-domain requires solving a Fredholm integral of the second kind, which is known as an ‘ill-posed inverse problem’. Hence the resulting DFRT's should not be trusted directly. In cases were impedance data can be modelled satisfactory with an Equivalent Circuit (EqC), built of known dispersion relations (e.g. (RQ), Gerischer, Finite Length Warburg) an analytic distribution function, G(τ), can be constructed. This can be compared with the inversion results obtained from Fourier Transform (FT), Tikhonov Regularization (TR) and multi-(RQ) CNLS fits (m(RQ)fit), thus allowing evaluation and validation of these methods This is illustrated in this contribution with four examples of SOFC cathodes with quite different properties. The results apply equally well to SOFC anodes (or SOEC cathodes).
AB - Electrochemical Impedance Spectroscopy (EIS) is a frequently used method to characterize electrodes for Solid Oxide Fuel Cells (SOFC) or Electrolyzer Cells (SOEC). The porous microstructures, use of composite structures and sometimes extra functional layers in an electrode, result often in impedance spectra that are difficult to analyze. Transformation of the impedance into a distribution function of relaxation times (DFRT) is about to become a new standard in EIS analysis. This inversion to the τ-domain requires solving a Fredholm integral of the second kind, which is known as an ‘ill-posed inverse problem’. Hence the resulting DFRT's should not be trusted directly. In cases were impedance data can be modelled satisfactory with an Equivalent Circuit (EqC), built of known dispersion relations (e.g. (RQ), Gerischer, Finite Length Warburg) an analytic distribution function, G(τ), can be constructed. This can be compared with the inversion results obtained from Fourier Transform (FT), Tikhonov Regularization (TR) and multi-(RQ) CNLS fits (m(RQ)fit), thus allowing evaluation and validation of these methods This is illustrated in this contribution with four examples of SOFC cathodes with quite different properties. The results apply equally well to SOFC anodes (or SOEC cathodes).
KW - Electrochemical Impedance Spectroscopy (EIS)
KW - Electrodes
KW - Finite Length Warburg (FLW)
KW - Gerischer dispersion
KW - Distribution function of relaxation times (DFRT)
UR - http://www.scopus.com/inward/record.url?scp=85037982334&partnerID=8YFLogxK
U2 - 10.1016/j.ssi.2017.11.021
DO - 10.1016/j.ssi.2017.11.021
M3 - Article
AN - SCOPUS:85037982334
VL - 314
SP - 103
EP - 111
JO - Solid state ionics
JF - Solid state ionics
SN - 0167-2738
ER -