Batteries, Vol. 7, Pages 49: Analysis and Investigation of Thermal Runaway Propagation for any Mechanically Constrained Lithium-Ion Pouch Cell Module

Batteries, Vol. 7, Pages 49: Analysis and Investigation of Thermal Runaway Propagation for a Mechanically Constrained Lithium-Ion Pouch Cell Module

Batteries doi: 10. 3390/batteries7030049

Authors: Luigi Aiello Ilie Hanzu Gregor Gstrein Eduard Ewert Christian Ellersdorfer Wolfgang Sinz

Within this paper, tests and analysis of thermal runaway propagation for commercial modules consisting of four 41 Ah Li-ion pouch cells are presented. Module samples were tested at 100% state-of-charge and mechanically constrained between two steel plates to provide thermal and mechanical contact between the parts. Voltage and temperature of each cell were monitored during the whole experiment. The triggering of the exothermal reactions was obtained by overheating one cell of the stack with a flat steel heater. In preliminary studies, the melting temperature of the separator was measured (from an extracted sample) with differential scanning calorimetry and thermogravimetric analysis techniques, revealing a tri-layers separator with two melting points (≈135 °C and ≈170 °C). The tests on module level revealed 8 distinct phases observed and analyzed in the respective temperature ranges, including smoking, venting, sparkling, and massive, short circuit condition. The triggering temperature of the cells resulted to be close to the melting temperature of the separator obtained in preliminary tests, confirming that the violent exothermal reactions of thermal runaway result from the internal separator failure. Postmortem inspections of the modules revealed the internal electrical failure path in one cell and the propagation of the internal short circuit in its active material volume, suggesting that the expansion of the electrolyte plays a role in the short circuit propagation at the single cell level. The complete thermal runaway propagation process was repeated on 5 modules and ended on average 60 s following the first thermal runaway triggered cell reached a top temperature of 1100 °C.

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Batteries, Vol. 7, Pages fifty two: Combining the Distribution associated with Relaxation Times from EIS and Time-Domain Data pertaining to Parameterizing Equivalent Circuit Models of Lithium-Ion Batteries

Batteries, Vol. 7, Pages 52: Combining the Distribution of Rest Times from EIS and Time-Domain Data for Parameterizing Equivalent Circuit Models associated with Lithium-Ion Batteries Batteries doi: 10. 3390/batteries7030052 Authors: Leo Wildfeuer Philipp Gieler Alexander Karger ECM are a widely used modeling approach regarding lithium-ion batteries in engineering applications. The RC elements, which display the […]