scholarly journals Simulation of Spatial Strain Inhomogeneities in Lithium-Ion-Cells Due to Electrode Dilation Dependent on Internal and External Cell Structures

2021 ◽  
Author(s):  
Fabian Ebert ◽  
Markus Spielbauer ◽  
Maximilian Bruckmoser ◽  
Markus Lienkamp
Keyword(s):  
Energy Density ◽  
Lithium Ion ◽  
Cell Types ◽  
Post Mortem ◽  
Lithium Ion Cells ◽  
Cell Material ◽  
Cell Structures ◽  
Cell Energy ◽  
Simulation Results ◽  
Different Cell Types

Electrochemical-mechanical interactions, in particular pressure-induced ones, have been identified to be a cause for lithium-plating in lithium-ion cells. Mechanically-induced porosity inhomogeneities in the separator layers due to electrode expansion during charging especially lead to cell internal balancing currents and can cause localized plating. To identify cell-format and cell-material dependent mechanical weak spots, a layer-resolved mechanical simulation of different cell types and cell-material combinations is presented in this work. The simulation results show distinctive layer strain patterns for different cell-types that coincide with localized lithium-plating found in post-mortem cells. Additionally, the effects of cell bracing in battery modules is investigated and a method to mitigate the increased layer strain due to bracing counterforces is proposed that also increases cell energy density for hardcase-type automotive cells.

Simulation of Spatial Strain Inhomogeneities in Lithium-Ion-Cells Due to Electrode Dilation Dependent on Internal and External Cell Structures

2020 ◽  
Author(s):  
Fabian Ebert ◽  
Markus Spielbauer ◽  
Maximilian Bruckmoser ◽  
Markus Lienkamp
Keyword(s):  
Energy Density ◽  
Lithium Ion ◽  
Cell Types ◽  
Post Mortem ◽  
Lithium Ion Cells ◽  
Cell Material ◽  
Cell Structures ◽  
Cell Energy ◽  
Simulation Results ◽  
Different Cell Types

Electrochemical-mechanical interactions, in particular pressure-induced ones, have been identified to be a cause for lithium-plating in lithium-ion cells. Mechanically-induced porosity inhomogeneities in the separator layers due to electrode expansion during charging especially lead to cell internal balancing currents and can cause localized plating. To identify cell-format and cell-material dependent mechanical weak spots, a layer-resolved mechanical simulation of different cell types and cell-material combinations is presented in this work. The simulation results show distinctive layer strain patterns for different cell-types that coincide with localized lithium-plating found in post-mortem cells. Additionally, the effects of cell bracing in battery modules is investigated and a method to mitigate the increased layer strain due to bracing counterforces is proposed that also increases cell energy density for hardcase-type automotive cells.

In-Plane Stiffness and Yield Strength of Periodic Metal Honeycombs

2004 ◽  
Vol 126 (2) ◽  
pp. 137-156 ◽  
Author(s):  
A.-J. Wang ◽  
D. L. McDowell
Keyword(s):  
Mechanical Properties ◽  
Yield Strength ◽  
Relative Density ◽  
Cell Types ◽  
Elastic Stiffness ◽  
Honeycomb Structures ◽  
Initial Yield ◽  
Cell Structures ◽  
Plane Anisotropy ◽  
Different Cell Types

In-plane mechanical properties of periodic honeycomb structures with seven different cell types are investigated in this paper. Emphasis is placed on honeycombs with relative density between 0.1 and 0.3, such that initial yield is associated with short column compression or bending, occurring prior to elastic buckling. Effective elastic stiffness and initial yield strength of these metal honeycombs under in-plane compression, shear, and diagonal compression (for cell structures that manifest in-plane anisotropy) are reported as functions of relative density. Comparison among different honeycomb structures demonstrates that the diamond cells, hexagonal periodic supercells composed of six equilateral triangles and the Kagome cells have superior in-plane mechanical properties among the set considered.

scholarly journals Accelerated Aging Characterization of Lithium-ion Cells: Using Sensitivity Analysis to Identify the Stress Factors Relevant to Cyclic Aging

Batteries ◽  
2020 ◽  
Vol 6 (1) ◽  
pp. 6 ◽  
Author(s):  
Tanja Gewald ◽  
Adrian Candussio ◽  
Leo Wildfeuer ◽  
Dirk Lehmkuhl ◽  
Alexander Hahn ◽  
...  
Keyword(s):  
Sensitivity Analysis ◽  
Accelerated Aging ◽  
Lithium Ion ◽  
Simulation Models ◽  
Cell Types ◽  
Stress Factors ◽  
Worst Case ◽  
Lithium Ion Cells ◽  
Aging Models ◽  
Semi Empirical

As storage technology in electric vehicles, lithium-ion cells are subject to a continuous aging process during their service life that, in the worst case, can lead to a premature system failure. Battery manufacturers thus have an interest in the aging prediction during the early design phase, for which semi-empirical aging models are often used. The progress of aging is dependent on the application-specific load profile, more precisely on the aging-relevant stress factors. Still, a literature review reveals a controversy on the aging-relevant stress factors to use as input parameters for the simulation models. It shows that, at present, a systematic and efficient procedure for stress factor selection is missing, as the aging characteristic is cell-specific. In this study, an accelerated sensitivity analysis as a prior step to aging modeling is proposed, which is transferable and allows to determine the actual aging-relevant stress factors for a specific lithium-ion cell. For the assessment of this accelerated approach, two test series with different acceleration levels and cell types are performed and evaluated. The results show that a certain amount of charge throughput, 100 equivalent full cycles in this case, is necessary to conduct a statistically significant sensitivity analysis.

scholarly journals The effect of charging rate on the graphite electrode of commercial lithium-ion cells: A post-mortem study

2016 ◽  
Vol 335 ◽  
pp. 189-196 ◽  
Author(s):  
L. Somerville ◽  
J. Bareño ◽  
S. Trask ◽  
P. Jennings ◽  
A. McGordon ◽  
...  
Keyword(s):  
Graphite Electrode ◽  
Lithium Ion ◽  
Post Mortem ◽  
Lithium Ion Cells ◽  
Charging Rate
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