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Poster-No.

P2-023

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Employing lower temperatures can render lithium batteries inert, halting almost all chemical reactions within the cells. Our in-house developed high-precision nail penetration setup has already provided valuable insights how critically damaged lithium battery cells behave at low temperatures. In the present study, tests were performed on three different cell types with varied cathode types and formats – each subjected to varying temperatures. These tests serve as the basis for establishing conditions for safe transportation. In this study, the tested LIB cells were conditioned to 20 °C and then cooled to below -80 °C with a pre-tempered nitrogen stream. This was followed by predefined damage with a nail depth which led to a repeatable TD in reference nail tests at 20 °C. This study reveals three essential areas in connection with the damage of LIB cells at low temperatures during the thawing process. In addition to the initial reaction temperature (IRT), where no reactions of the damaged LIB cells are evident, phase transitions and a return of the voltage can be seen during further thawing. In particular, the increasing ripples in the voltage curve indicate incipient reactions of thermal runaway. However the outcome of a thermal runaway is mainly influenced by the conductivty of the nail penetration induced short circuit.The determination of the IRT based on the change in the temperature gradient during thawing of the critically damaged cells in this study also shows that the IRT does not necessarily depend on capacitance or cathode chemistry. Finally the cell type indivudal IRT enables a safe transport of critical damaged LIB cells.