Lithium-ion batteries are well established as energy storage devices for a wide range of mobile applications from cell phones through power tools to electric vehicles. The different types of usage lead to distinct requirements concerning the battery system, resulting in customized dimensioning of the single components. For the sustainable, technically and economically efficient battery production and utilization, a holistic design and optimization of the cells and the whole battery pack is indispensable. Optimal performance and lifetime of the battery cells do not only require careful consideration of the electrical and mechanical properties, but in particular also the thermal properties, with their significant impact on temperature and its distribution that do in turn strongly interact with the aforementioned properties.

For the development of thermally optimized cells, a realistic picture of the potential impact of varying thermal cell properties is crucial. In this context, a sensitivity analysis was conducted to determine the variables with the greatest impact on density, specific heat capacity and thermal conductivity. Hereby a variation of layer thicknesses and material data of the individual components was carried out and has given an insight into the possible range of the effective thermal properties of the whole cell stack with or without the outer separator layer and the pouch foil. With the derived information, it was possible to minimize the temperature gradient along the thickness of the cell with analytical calculation methods and to create an optimized cell structure within the given range considering the thermal aspects.

Furthermore, the influence of the thermal properties on the heat removal from the battery cell and the temperature distribution along the thickness of the stack were investigated. Different thermal boundary conditions were applied in a numerical model of the cell stack, providing information about the performance and suitability of different cooling systems.