Two-dimensional impedance data analysis by the distribution of relaxation times

Mertens, Andreas; Granwehr, Josef

doi:10.1016/j.est.2017.07.029

Cited by 26 publications

(20 citation statements)

References 34 publications

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“…has been demonstrated to improve the signal-to-noise ratio and thus, data resolution compared to 1D. [173] Beyond equivalent circuit modelling, machine learning (ML) can use large EIS datasets taken over wide parameter space to understand degradation [174] and predict parameters such as SoC and state-of-health [175] in LiBs. The current database of EIS measurements for ASBs is not nearly as large, but is poised to grow, and knowledge gained from applying ML will likely complement chemical and physical insights from the other techniques discussed here.…”

Section: Emerging Eis-related Techniques For Li-ion Batteriesmentioning

confidence: 99%

Electrochemical Impedance Spectroscopy for All‐Solid‐State Batteries: Theory, Methods and Future Outlook

et al. 2021

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Electrochemical impedance spectroscopy (EIS) is widely used to probe the physical and chemical processes in lithium (Li)-ion batteries (LiBs). The key parameters include state-of-charge, rate capacity or power fade, degradation and temperature dependence, which are needed to inform battery management systems as well as for quality assurance and monitoring. All-solid-state batteries using a solid-state electrolyte (SE), promise greater energy densities via a Li metal anode as well as enhanced safety, but their development is in its nascent stages and the EIS measurement, cell set-up and modelling approach can be vastly different for various SE chemistries and cell configurations. This review aims to condense the current knowledge of EIS in the context of state-of-the-art solid-state electrolytes and batteries, with a view to advancing their scale-up from the laboratory to commercial deployment. Experimental and modelling best practices are highlighted, as well as emerging impedance methods for conventional LiBs as a guide for opportunities in the solid-state.

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Section: Emerging Eis-related Techniques For Li-ion Batteriesmentioning

confidence: 99%

Electrochemical Impedance Spectroscopy for All‐Solid‐State Batteries: Theory, Methods and Future Outlook

et al. 2021

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“…As complex Nyquist plots often lead to misinterpretations of the number of polarization processes, the distribution of relaxation times (DRT) method is used. Here, the values for real and imaginary parts of the impedance are transformed into the frequency domain which helps to separate the individual time constants 71 . Besides a better separation of the related time constants, the 2-dimensional DRT also allows for a better identification of the serial resistance as well as inductive effects as no non-negativity constraint is used.…”

Section: Electrochemical In-operando Analysis Of Ascs: Drt-analysis Amentioning

confidence: 99%

Chrome Poisoning of Non-Manganiferous Cathode Materials in Solid Oxide Fuel Cells (SOFCs)

et al. 2017

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This work is focused on the degradation effect of chrome poisoning on LSCF cathodes for high temperature SOFCs aimed at an increase of the cell durability. Therefore the electrochemical performance of single cells is investigated at open cell voltage (OCV) and polarizations of 0.5, 0.75 and 1 A*cm -2 as well as at temperatures of 900 and 700°C in presence/absence of a chrome source. To identify the cathode related processes of the impedance spectra without anode contributions, symmetrical half cells were tested as well. It is observed that in presence of a chrome source the ohmic as well as the polarization resistances increase. At a temperature of 900 °C and a humidity of 3.5 %, the polarization resistance shows a stronger increase at current densities above 0.75 A*cm -² whereas the polarization resistance remains linear. Furthermore, measurements at 700 °C confirmed that also the operation temperature serves as a factor for accelerated chrome related cell degradation.

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“…As complex Nyquist plots often lead to misinterpretations of the number of polarization processes, the distribution of relaxation times (DRT) method is used. Here, the values for real and imaginary parts of the impedance are transformed into the frequency domain which helps to separate the individual time constants 71 . Figure 5.6 represents the 2-dimensional transformation of the respective impedance results at 750 °C and open cell conditions.…”

Section: Electrochemical In-operando Analysis Of Ascs: Drt-analysis Amentioning

confidence: 99%

Chrome Poisoning of Non-Manganiferous Cathode Materials in Solid Oxide Fuel Cells (SOFCs)

Schiemann,

Vibhu,

Yildiz

et al. 2017

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Chrome poisoning is considered to be one of the main degradation issues of SOFC cathode materials and thus a major cause for decreased SOFC component performances in combination with a reduced durability [1, 2]. For this reason, deeper understanding of the related chrome degradation mechanisms is of fundamental interest. Since (La,Sr)(Co,Fe)O3 based cathodes show both, a good electronic and sufficient ionic conductivity, these materials are considered to be less susceptible towards chrome poisoning than pure electronic conductors such as (La,Sr)MnO3. Nevertheless, recent performed long-term stack tests showed similar poisoning effects for LSCF materials as seen for LSM cathodes, urging us to perform another in-depth analysis of the mechanisms of chrome poisoning in non-manganiferous cathode materials [3]. LSCF materials with different stoichiometry's (variable cobalt and iron contents) have been synthesized and analyzed regarding their phase purity and microstructure. Anode supported SOFCs were manufactured with these LSCF compositions and characterized by electrochemical measuring techniques (DC/AC measurements). Here, we mainly focus on impedance spectroscopy in a broad range of different operating conditions (e.g. temperature, current density, and humidity on the air side) in presence and absence of a suitable chromium source. Electrochemical impedance measurements performed at 900 °C and a cell voltage of 0.7 V in dry and humid air conditions (Figure 1) reveal that besides an initial formation step (I in Fig. 1) the ohmic and polarization resistances only show small deviations in absence of a chrome source (Rohm: dry ~ 0.125 Ω*cm², humid 0.127 - 0.130 Ω*cm²; Rpol: dry ~ 0.045 Ω*cm², humid 0.047 Ω*cm²; see Fig. 1). During a step-wise increase of current density, i.e. cathode polarization, over 48 hour periods both Rohm and Rpol remained stable (see Fig. 1). Besides the above mentioned 4-point measurements on full cells, 3-point measurements with a reference electrode were performed on symmetrical electrolyte supported half cells. By this means contributions from the Ni/YSZ anode to the overall cell impedance can be excluded and the individual cathode contributions investigated in more detail. In combination, both measuring setups should enable detailed information about the individual resistance contributions of the synthesized cathode materials with respect to the operating conditions. References [1]B. Wei, K. Chen, C.C. Wang, Z. Lüa, S.P. Jiang; “Cr deposition on porous La0.6Sr0.4Co0.2Fe0.8O3−δ electrodes of solid oxide cells under open circuit condition”; Solid State Ionics 281 (2015) 29–37 [2]L.G.J. de Haart, J. Mougin, O. Posdziech, J. Kiviaho, N.H. Menzler; “Stack Degradation in Dependence of Operation Parameters; the Real-SOFC Sensitivity Analysis”; FUEL CELLS 9 (6) (2009) 794–804 [3] N.H. Menzler, D. Sebold, Q. Fang; “Chromium-Related Degradation of Thin-Film Electrolyte SolidOxide Fuel Cell Stacks”; Journal of the Electrochemical Society, 162 (12) (2015) F1275-F1281 Figure 1

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Two-dimensional impedance data analysis by the distribution of relaxation times

Cited by 26 publications

References 34 publications

Electrochemical Impedance Spectroscopy for All‐Solid‐State Batteries: Theory, Methods and Future Outlook

Electrochemical Impedance Spectroscopy for All‐Solid‐State Batteries: Theory, Methods and Future Outlook

Chrome Poisoning of Non-Manganiferous Cathode Materials in Solid Oxide Fuel Cells (SOFCs)

Chrome Poisoning of Non-Manganiferous Cathode Materials in Solid Oxide Fuel Cells (SOFCs)

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