@article{KomsiyskaBuchbergerDiehletal.2021, author = {Komsiyska, Lidiya and Buchberger, Tobias and Diehl, Simon and Ehrensberger, Moritz and Hanzl, Christian and Hartmann, Christoph and H{\"o}lzle, Markus and Kleiner, Jan and Lewerenz, Meinert and Liebhart, Bernhard and Schmid, Michael and Schneider, Dominik and Speer, Sascha and St{\"o}ttner, Julia and Terbrack, Christoph and Hinterberger, Michael and Endisch, Christian}, title = {Critical review of intelligent battery systems}, volume = {14}, pages = {5989}, journal = {Energies}, subtitle = {challenges, implementation, and potential for electric vehicles}, number = {18}, publisher = {MDPI}, address = {Basel}, issn = {1996-1073}, doi = {https://doi.org/10.3390/en14185989}, year = {2021}, abstract = {This review provides an overview of new strategies to address the current challenges of automotive battery systems: Intelligent Battery Systems. They have the potential to make battery systems more performant and future-proof for coming generations of electric vehicles. The essential features of Intelligent Battery Systems are the accurate and robust determination of cell individual states and the ability to control the current of each cell by reconfiguration. They enable high-level functions like fault diagnostics, multi-objective balancing strategies, multilevel inverters, and hybrid energy storage systems. State of the art and recent advances in these topics are compiled and critically discussed in this article. A comprising, critical discussion of the implementation aspects of Intelligent Battery Systems complements the review. We touch on sensing, battery topologies and management, switching elements, communication architecture, and impact on the single-cell. This review contributes to transferring the best technologies from research to product development.}, language = {en} } @article{YuKiranEhrensbergeretal.2025, author = {Yu, Qing and Kiran, Iqra and Ehrensberger, Moritz and Streck, Luiza and Roth, Thomas and Jossen, Andreas and Endisch, Christian and Lewerenz, Meinert}, title = {Assigning Calendar Aging during Open Circuit and Float Current Analysis to Anode and Cathode Aging Using Three-Electrode Cells}, volume = {172}, pages = {060523}, journal = {Journal of the Electrochemical Society}, number = {6}, publisher = {IOP Publishing}, address = {Bristol}, issn = {1945-7111}, doi = {https://doi.org/10.1149/1945-7111/ade295}, year = {2025}, abstract = {Analyzing calendar aging by float current analysis, instead of solely repeating capacity tests, gains more insights into aging. However, the underlying mechanisms of the recharge current required to keep the voltage constant are not yet fully understood. Therefore, this study performs float current and additional open circuit voltage (OCV) tests on 3-electrode cells for four different voltages at 30 °C. By monitoring the potentials of the anode and the cathode over time individually, the aging rate on both electrodes and the present capacity can be calculated based on adjusting the electrode-specific OCV curves according to the voltage slippery theory. The electrode-specific aging and the capacity prediction show high agreement among both methods and the capacity tests at the end of the experiment. As a result, the capacity loss appears linear-like and is associated with the loss of active lithium mainly due to SEI formation on the anode. Additionally, a significant cathode voltage decay is observed especially for higher cell voltage. According to the literature, this is associated with cathode lithiation where the conductive salt is decomposed by inserting active lithium into the cathode masking SEI losses. Finally, OCV and float current analysis return comparable results and support present 2-electrode evaluation approaches.}, language = {en} } @article{AzzamEhrensbergerScheueretal.2023, author = {Azzam, Mohamed and Ehrensberger, Moritz and Scheuer, Reinhard and Endisch, Christian and Lewerenz, Meinert}, title = {Long-Term Self-Discharge Measurements and Modelling for Various Cell Types and Cell Potentials}, volume = {16}, pages = {3889}, journal = {Energies}, number = {9}, publisher = {MDPI}, address = {Basel}, issn = {1996-1073}, doi = {https://doi.org/10.3390/en16093889}, year = {2023}, abstract = {Self-discharge of lithium-ion cells leads to voltage decay over time. In this work, the self-discharge was measured at 30 °C for three cell types at various voltage levels for about 150 days in a constant voltage mode determining the current at a high precision (float current). All cells exhibit a transient part leading to a steady-state, which is no longer influenced by reversible effects. To study the effect of the check-ups on the steady-state float current, the cells, interrupted and not interrupted by check-ups, were compared. The results indicate that both the transient processes and steady-state currents are highly reproducible. In the first period of the float current, the polarization dominates the measured current, followed by the anode overhang effect dominating the process for a period of 5-30 days. After the decline of both processes, a mostly constant steady-state in the order of µA is observed. The check-up interruption generally shows no apparent effect on the reached steady-state and results only in an extended settling time. A model to simulate the transient process and steady-state of float currents was developed. The model shows a high accuracy in reproducing the results and identifying the time needed to reach the steady-state.}, language = {en} } @article{AzzamEhrensbergerEndischetal.2024, author = {Azzam, Mohamed and Ehrensberger, Moritz and Endisch, Christian and Lewerenz, Meinert}, title = {Accelerating float current measurement with temperature ramps revealing entropy insights}, volume = {2024}, pages = {114142}, journal = {Journal of Energy Storage}, number = {102, Part B}, publisher = {Elsevier}, address = {Science}, issn = {2352-1538}, doi = {https://doi.org/10.1016/j.est.2024.114142}, year = {2024}, language = {en} } @article{AzzamEhrensbergerEndischetal.2024, author = {Azzam, Mohamed and Ehrensberger, Moritz and Endisch, Christian and Sauer, Dirk Uwe and Lewerenz, Meinert}, title = {Comparison of dU/dQ, Voltage Decay, and Float Currents via Temperature Ramps and Steps in Li-ion Batteries}, volume = {8}, pages = {e202400627}, journal = {Batteries \& Supercaps}, number = {1}, publisher = {Wiley}, address = {Weinheim}, issn = {2566-6223}, doi = {https://doi.org/10.1002/batt.202400627}, year = {2024}, language = {en} }