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Comparative Study of Equivalent Circuit Models Performance in Four Common Lithium-Ion Batteries: LFP, NMC, LMO, NCA
Article

Combining the Distribution of Relaxation Times from EIS and Time-Domain Data for Parameterizing Equivalent Circuit Models of Lithium-Ion Batteries

1
Institute of Automotive Technology, Technical University of Munich, 80333 Munich, Germany
2
TWAICE Technologies GmbH, 80807 Munich, Germany
*
Author to whom correspondence should be addressed.
Academic Editor: Carlos Ziebert
Batteries 2021, 7(3), 52; https://doi.org/10.3390/batteries7030052
Received: 11 June 2021 / Revised: 14 July 2021 / Accepted: 19 July 2021 / Published: 2 August 2021
Equivalent circuit models (ECMs) are a widely used modeling approach for lithium-ion batteries in engineering applications. The RC elements, which display the dynamic loss processes of the cell, are usually parameterized by fitting the ECM to experimental data in either the time-domain or the frequency-domain. However, both types of data have limitations with regard to the observable time constants of electrochemical processes. This work proposes a method to combine time-domain and frequency-domain measurement data for parameterization of RC elements by exploiting the full potential of the distribution of relaxation times (DRT). Instead of using only partial information from the DRT to supplement a conventional fitting algorithm, we determine the parameters of an arbitrary number of RC elements directly from the DRT. The difficulties of automated deconvolution of the DRT, including regularization and the choice of an optimal regularization factor, is tackled by using the L-curve criterion for optimized calculation of the DRT via Tikhonov regularization. Three different approaches to merge time- and frequency-domain data are presented, including a novel approach where the DRT is simultaneously calculated from electrochemical impedance spectoscropy (EIS) and pulse relaxation measurements. The parameterized model for a commercial 18650 NCA cell was validated during a validation cycle consisting of constant current and real-world automotive cycling and yields a relative improvement of over 40% compared to a conventional EIS-fitting algorithm. View Full-Text
Keywords: lithium-ion batteries; equivalent circuit model; electrochemical impedance spectroscopy; distribution of relaxation times; Tikhonov regularization lithium-ion batteries; equivalent circuit model; electrochemical impedance spectroscopy; distribution of relaxation times; Tikhonov regularization
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MDPI and ACS Style

Wildfeuer, L.; Gieler, P.; Karger, A. Combining the Distribution of Relaxation Times from EIS and Time-Domain Data for Parameterizing Equivalent Circuit Models of Lithium-Ion Batteries. Batteries 2021, 7, 52. https://doi.org/10.3390/batteries7030052

AMA Style

Wildfeuer L, Gieler P, Karger A. Combining the Distribution of Relaxation Times from EIS and Time-Domain Data for Parameterizing Equivalent Circuit Models of Lithium-Ion Batteries. Batteries. 2021; 7(3):52. https://doi.org/10.3390/batteries7030052

Chicago/Turabian Style

Wildfeuer, Leo, Philipp Gieler, and Alexander Karger. 2021. "Combining the Distribution of Relaxation Times from EIS and Time-Domain Data for Parameterizing Equivalent Circuit Models of Lithium-Ion Batteries" Batteries 7, no. 3: 52. https://doi.org/10.3390/batteries7030052

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