Impedanzbasierte Modellierung von Lithium-Ionen Zellen und deren Degradationsverhalten

Gantenbein, Sophia

doi:10.5445/ksp/1000099175

Cited by 2 publications

(7 citation statements)

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“…The resistance then increases again and at the end of the test the worst cell has a value of 137% and the best cell has a value of 106%. A decrease in internal resistance was also observed in [31,36] and was associated with the impedance of the anode. At the end of aging, the order from the worst to the best cell is identical for both the internal resistances and the capacity values of the cells.…”

Section: Aging Testmentioning

confidence: 78%

“…The newly visible semicircle in the aged state at a slightly higher frequency can be attributed to the increasing charge transfer losses due to the growth of the Solid Electrolyte Interphase (SEI) [5]. The increase in the other semicircle can be attributed to a deterioration of the charge transfer at the cathode [5,31]. The deterioration of the charge transfer is due to the formation of a surface film on the cathode or to a change in the structure of the cathode [44].…”

Section: Electrochemical Impedance Spectroscopymentioning

confidence: 99%

“…In the current step response measurement, a change in the cell voltage is caused by the application of a current pulse for a defined time. The internal resistance can then be calculated via the voltage change and the intensity of the current pulse [5,31]. The internal resistances were calculated at an SoC of 100% with a pulse discharge of 1C after 1 s. The mean value is 56.7 mΩ with a standard deviation of 0.9 mΩ.…”

Section: Experimental Setup and Cell Selectionmentioning

confidence: 99%

“…This behavior is mainly caused by the inductive influences of the measurement setup as well as by the geometry of the cell, especially by the skin effect in round cells [40,41]. At low frequencies, there is a steeply rising branch caused by diffusion processes that cannot be fully detected by EIS [31]. Important for the observation of the aging processes are the capacitive range and the point with Im(Z) = 0.…”

Section: Electrochemical Impedance Spectroscopymentioning

confidence: 99%

“…Therefore, for cells with NMC cathode and graphite anode, as in this work, the DVA is mainly used to determine the anode aging and the loss of usable lithium. From the literature, it can be assumed that the NMC cathode also suffers a capacity loss during operation; however, the literature shows that the NMC cathode is usually not a limiting factor of the capacity of the cell [31].…”

Section: Differential Voltage Analysismentioning

confidence: 99%

See 4 more Smart Citations

Aging Determination of Series-Connected Lithium-Ion Cells Independent of Module Design

et al. 2023

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In this work, a battery consisting of eight commercial NMC/graphite cells connected in series was cycled to 60% of its initial capacity. During the test, special care was taken to ensure that the results were not influenced by either the module assembly or the module design. For this purpose, the cells were virtually connected in a laboratory environment with the help of the test device as if they were operated together in a battery. Extrinsic influences that affect cell aging were thus reduced to a minimum. Differential Voltage Analysis (DVA), Electrochemical Impedance Spectrum (EIS), and relaxation measurements were performed to analyze the aging behavior of each cell. The results show that despite a theoretically perfect module design, Cell-to-Cell Variations (CtCV) occurred during aging. The shifting Depth of Discharge (DoD) values among the cells further amplify CtCV. Lithium plating was also observed in the faster aging cells after cyclic aging, suggesting that this aging effect contributes significantly to the development of CtCV. After the aging test, the battery was equipped with an active balancing system that maximizes capacity utilization. More important, the balancing charges which are calculated iteratively within the used balancing algorithm show a strong correlation to the pure capacity losses and thus provide a new way to determine the capacity values of each cell individually without disassembling the battery.

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Section: Aging Testmentioning

confidence: 78%

Section: Electrochemical Impedance Spectroscopymentioning

confidence: 99%

Section: Experimental Setup and Cell Selectionmentioning

confidence: 99%

Section: Electrochemical Impedance Spectroscopymentioning

confidence: 99%

Section: Differential Voltage Analysismentioning

confidence: 99%

See 3 more Smart Citations

Aging Determination of Series-Connected Lithium-Ion Cells Independent of Module Design

et al. 2023

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Full-, Half-, and Symmetrical Cell Analysis of Lithium-Ion Battery Using Impedance and Nonlinear Frequency Response

Lee,

Chan,

Ulrich

et al. 2024

J. Electrochem. Soc.

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This study presents an in-depth analysis of the cathode and anode of a commercial 18650 lithium-ion battery by comparing their dynamic behaviors systematically with that of two additional experimental cell setups: (i) full-cell in a three-electrode setup and (ii) symmetrical cathode and anode cells. The analysis involves subjecting the cells to electrochemical impedance spectroscopy, distribution of relaxation times, and nonlinear frequency response analysis at different state-of-charges. Our findings highlight the importance of analyzing the electrodes in all three setups. The impedance and nonlinear frequency response features of the full-cell are also observed in the electrode-resolved cells. Symmetrical cells exhibit stronger impedance and nonlinear responses compared to the commercial cell and the cell with reference electrode, yet they allow identifying contributions of the single cells without artifacts from inductive loops caused by the reference electrode. By correlating nonlinear signals and characteristic peaks across different cell setups, cathode and anode processes and their respective characteristic frequencies can be clearly identified.

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Impedanzbasierte Modellierung von Lithium-Ionen Zellen und deren Degradationsverhalten

Cited by 2 publications

References 0 publications

Aging Determination of Series-Connected Lithium-Ion Cells Independent of Module Design

Aging Determination of Series-Connected Lithium-Ion Cells Independent of Module Design

Full-, Half-, and Symmetrical Cell Analysis of Lithium-Ion Battery Using Impedance and Nonlinear Frequency Response

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