Investigating the mechanical in-plane characteristics of lithium-ion pouch cells under crush loads

The mechanical properties and deformation behaviour of a Lithium-Ion pouch cell are crucial to evaluate its safety and form the basis for creating valid simulation models. However, little is known about the in-plane characteristics of pouch cells in a battery pack. This study proposes a novel test set-up to analyse the pouch cells' in-plane characteristics, mimicking the real confinement condition of a pouch cell in a battery module. Two pouch cells were tested in six in-plane load configurations with a cylindrical indenter, and the forces, displacements and buckling histories were monitored in the battery cell's in-plane and out-of-plane directions. Therefore, the influence of the parameters jelly roll structure, preload, and out-of-plane confinement were evaluated and correlated with the mechanical and failure behaviour. We found that the mechanical in-plane characteristics correlate with their out-of-plane characteristics and the deformation history of the cell, especially the buckling, by additionally monitoring the tests with two cameras. The findings suggest that the mechanical characteristics of pouch cells of different formats are similar. The results show that safety can be influenced by battery module design, such as preload, cell orientation or compression pad stiffness. Therefore, the crash safety of vehicles can be improved by cost-efficient measures.