Investigation of the Effective Thermal Conductivity of Cell Stacks of Li‐Ion Batteries

Knowledge of the thermal transport properties of the individual battery components and their combination is required for the design of thermally optimized lithium‐ion batteries. Based on this, the limiting components can be identified and potentially improved. In this contribution, the microstructures of commercial porous electrode coatings, electrode stacks, and cell stacks are reconstructed based on experimentally determined structure parameters using a specifically developed structure generation routine. The effective thermal conductivity of the generated stacked structures is then determined by a numerical tool developed in‐house based on the finite‐volume method. The results are compared with an analytical model for fast accurate predictions which takes the morphological parameter sets and the geometry of the stacks into account. Both models are used to identify the system‐limiting components via selected simulation studies. Finally, the results of both models are compared with experimental data for commercial electrode stacks and common literature values for cell stacks. Thermal limitation! A numerical and analytical model approach is developed to describe the effective thermal conductivity of cell stacks perpendicular and parallel to the cell layer directions. Herein, it is demonstrated in detail that the heat transport in lithium‐ion cells is mainly limited by the high thermal resistance of the separator layers.