A hybrid approach to derive macro- and meso-mechanic cell models for vibrational investigations of lithium-ion pouch cells

Lithium-ion batteries are the core component of every energy storage system in modern electric vehicles. In order to represent the multi-physical processes in these battery systems in simulations, different modeling approaches are needed depending on the application area. In this work, two methods are presented to derive state-of-charge dependent material models for lithium-ion pouch cells suitable for modal analysis using the finite elements method. As a starting point, the non-destructive measurement method of experimental modal analysis is performed at different states of charge. Using the Dakota optimization framework, material models are derived by minimizing the deviations between measured and calculated natural frequencies. On a meso-mechanic level, a homogenization approach is presented, which makes it possible to use material parameters from tensile and compression tests of the individual cell layers to derive material models for the calculation of natural frequencies at cell level. A method is described to perform state-of-charge dependent modal calculations on pouch cells. Thus, a practical approach was created to derive models for vibrational investigations from low-cost, standardized tests. • Experimental determination of modal parameters of lithium-ion pouch cells. • Effects on the natural frequencies for different states of charge. • Determination of material models for pouch cells using optimization methods. • Definition of a state of charge dependent layer within a homogenization scheme. • Practical method to derive models for NVH investigations from standardized tests.