Deformation Behavior of Single Prismatic Battery Cell Cases and Cell Assemblies Loaded by Internal Pressure

The safety of electrochemical energy storage system depends on the structural integrity of the call containment. Nominal values of cell case dimensions and material properties are the standard inputs for the mechanical analysis of prismatic lithium-ion batteries. However, such data usually do not account for any considerations on the influence of the manufacturing processes of the cell case. This study investigates the effects of the cell wall thickness and elastic modulus, resulting from deep-drawing process, on the cell and cell assembly response. It is found that the deep-drawing process degrades Young’s modulus relative to standard values and leads to a spatial variation in the wall thickness of the cell case. The use of actual cell case material properties and cell wall thickness values is required to obtain validated finite element models of the battery cell case. Using experiments on internal pressure loaded single battery cells and finite element computations, it is demonstrated that the use of nominal cell casing characteristics significantly underestimates the resistance provided by the cell case to counter swelling of the active battery components.