Experiments and 3D detailed modeling for a pouch battery cell under impact loading

Mechanical behavior of Lithium-ion batteries under dynamic impact loading is crucial in assessing and improving the crash safety of batteries. To understand the possible causes of internal short circuit (ISC) in the impacted batteries, both experimental and numerical methods are necessary. Quasi-static and dynamic tests for a type of pouch-type battery cell are performed according to a UN standard. The mechanical characterization of all the component materials in the battery is carefully carried out under different strain rate and loading conditions. Then a detailed 3D Finite Element (FE) Model of the pouch cell with all the components is established. Combining the experimental and numerical approaches, the dynamic deformation process under the UN 38.3 Impact tests and the corresponding failure mechanism of pouch cells are firstly captured. Meanwhile, the conditions for the occurrence of thermal runaway are investigated with the comparison of quasi-static and dynamic tests. It is believed that the rough fracture surface and the crushed powdery residue are responsible for the continuous internal short circuits and thermal runaway of the broken batteries. To improve the crash safety performance of the pouch cell, some safety suggestions are proposed.