Evaluation of temperature-dependent mechanical properties of lithium-ion batteries: A hybrid experimental modal analysis and finite element method approach

The mechanical properties that influence the performance and durability of lithium-ion batteries under various operating conditions are crucial yet often overlooked. This work aims to deepen the understanding of these properties by developing a temperature-dependent orthotropic constitutive model. We present a detailed investigation of the mechanical responses of lithium-ion batteries, including Young's and Shear Moduli, under various temperature conditions. To validate our findings, we have developed and implemented a robust finite element model that considers the elastic behavior and is based on experimental data from Experimental Modal Analysis of a lithium-ion pouch cell. This study unveils the significant temperature-dependent nature of these orthotropic mechanical properties. For instance, our model reveals a substantial reduction of the in plane Young's Modulus (E) from 16 385.65 MPa at 17.7 °C to 6676.12 MPa at 31.9 °C. Our model's parameters, particularly E_X and E_Z, display strong influence on the overall mechanical responses. We compare our results with published literature data which shows a good alignment with our findings. This study introduces a non-destructive approach to evaluate and quantify the mechanical parameters of lithium-ion pouch cells at the full cell level under various operating conditions. The insights derived from this study can inform the development of more efficient finite element models, thereby enhancing the understanding of mechanical properties of lithium-ion batteries.