Focus:

  • Floater hardware development
  • Research of float current analysis on battery cells
  • Development of ideal measurement routines
  • Automation for accelerated application
  • Modeling of aging

Summary:

The young research group I-BasE has set itself the goal of developing new industry-relevant test strategies for lithium-ion cells in an interdisciplinary and international team, which consider reversible capacity effects and additional effects due to the acceleration of aging tests.

For this purpose, quasi-static self-discharge currents - called float currents - are investigated, which show a strong correlation to the capacity loss of the cells. Particularly attractive is the fast and direct measurement of aging, which, among other things, leads to a rapid characterization. By integrating electrochemical impedance spectroscopy (EIS), additionally resistances can be measured at low noise.

This will increase the prediction quality and at the same time shorten the testing time for domestic enterprises. Due to the inexpensive, comprehensive and fast characterization of the cells, they can be selected more precisely to save costs and accelerate innovation cycles.

The project has a total volume of 2.2 million euros and includes 4-5 research assistants over 5 years.

    Relevant literature:

    Publications float currents
    • M. Azzam, M. Ehrensberger, C. Endisch, M. Lewerenz, Accelerating float current measurement with temperature ramps revealing entropy insights, Journal of Energy Storage, Volume 102, Part B (2024). https://doi.org/10.1016/j.est.2024.114142.
    • M. Azzam, C. Endisch, M. Lewerenz, Evaluating the Aging-Induced Voltage Slippery as Cause for Float Currents of Lithium-ion Cells, Batteries 10(1) (2024) 3. https://doi.org/10.3390/batteries10010003.
    • M. Azzam, M. Ehrensberger, R. Scheuer, C. Endisch, M. Lewerenz, Long-Term Self-Discharge Measurements and Modelling for Various Cell Types and Cell Potentials, Energies 16(9) (2023) 3889. https://doi.org/10.3390/en16093889.
    • M. Theiler, C. Endisch and M. Lewerenz, Float Current Analysis for Fast Calendar Aging Assessment of 18650 Li(NiCoAl)O2/Graphite Cells, Batteries 7 (2021) 22. https://doi.org/10.3390/batteries7020022.
    • M. Lewerenz, J. Münnix, J. Schmalstieg, S. Käbitz, M. Knips, A. Warnecke, D.U. Sauer, New method evaluating currents keeping the voltage constant for fast and high resolved measurement of Arrhenius relation and capacity fade, J. Power Sources 353 (2017) 144–151. https://doi:10.1016/j.jpowsour.2017.03.136.
    Publications homogeneity
    • M. Lewerenz, P. Dechent, D.U. Sauer, Investigation of capacity recovery during rest period at different states-of-charge after cycle life test for prismatic Li(Ni1/3Mn1/3Co1/3)O2-graphite cells, Journal of Energy Storage 21 (2019) 680–690. https://doi.org/10.1016/j.est.2019.01.004.
    • M. Lewerenz, D.U. Sauer, Evaluation of cyclic aging tests of prismatic automotive LiNiMnCoO2-Graphite cells considering influence of homogeneity and anode overhang, Journal of Energy Storage 18 (2018) 421–434. https://doi.org/10.1016/j.est.2018.06.003.
    • M. Lewerenz, G. Fuchs, L. Becker, D.U. Sauer, Irreversible calendar aging and quantification of the reversible capacity loss caused by anode overhang, Journal of Energy Storage 18 (2018) 149–159. https://doi.org/10.1016/j.est.2018.04.029.
    • M. Lewerenz, A. Marongiu, A. Warnecke, D.U. Sauer, Differential voltage analysis as a tool for analyzing inhomogeneous aging: a case study for LiFePO4|Graphite cylindrical cells, J. Power Sources 368 (2017) 57–67. https://doi:10.1016/j.jpowsour.2017.09.059.
    • M. Lewerenz, A. Warnecke, D.U. Sauer, Introduction of capacity difference analysis (CDA) for analyzing lateral lithium-ion flow to determine the state of covering layer evolution, J. Power Sources 354 (2017) 157–166. https://doi.org/10.1016/j.jpowsour.2017.04.043.
    Publications overhang effect
    • M. Lewerenz, J. Münnix, J. Schmalstieg, S. Käbitz, M. Knips, D.U. Sauer, Systematic aging of commercial LiFePO4jGraphite cylindrical cells including a theory explaining rise of capacity during aging, J. Power Sources 345 (2017) 254–263. https://doi:10.1016/j.jpowsour.2017.01.133.
    • M. Lewerenz, G. Fuchs, L. Becker, D.U. Sauer, Irreversible calendar aging and quantification of the reversible capacity loss caused by anode overhang, Journal of Energy Storage 18 (2018) 149–159. https://doi.org/10.1016/j.est.2018.04.029.
    • M. Lewerenz, P. Dechent, D.U. Sauer, Investigation of capacity recovery during rest period at different states-of-charge after cycle life test for prismatic Li(Ni1/3Mn1/3Co1/3)O2-graphite cells, Journal of Energy Storage 21 (2019) 680–690. https://doi.org/10.1016/j.est.2019.01.004.

    Contact

    Senior Research Associate Institute of Innovative Mobility (IIMo)
    Dr. Meinert Lewerenz
    Phone: +49 841 9348-6507
    Room: S421
    E-Mail:
    Research Assistant Institute of Innovative Mobility (IIMo)
    Mohamed Azzam, M.Sc.
    Phone: +49 841 9348-5189
    Room: S421
    E-Mail:
    Research Assistant Institute of Innovative Mobility (IIMo)
    Qing Yu
    Phone: +49 841 9348-5172
    Room: S421
    E-Mail:
    Research Assistant Institute of Innovative Mobility (IIMo)
    Iqra Kiran, M.Sc.
    Phone: +49 841 9348-4153
    Room: S421
    E-Mail:
    Research Assistant Institute of Innovative Mobility (IIMo)
    Dr. Andriy Taranovskyy
    Phone: +49 841 9348-5188
    Room: S421
    E-Mail:
    Research Assistant Institute of Innovative Mobility (IIMo)
    Andreas Gallenberger, B.Sc.
    Phone: +49 841 9348-5201
    Room: S421
    E-Mail:

    Project partners

    Funding

    This project is funded by the German Federal Ministry of Education and Research within the framework of the announcement "BattFutur" (grant number 03XP0442).