Challenges and new methodologies for battery development starting at cell level

A battery system consists of hundreds of battery cells that need to be well understood, monitored and managed to guarantee optimal performance of the overall system. This becomes even more challenging considering that the properties of individual battery cells are subject to certain variability. This applies to new cells due to various manufacturing and environmental factors, and even more so to aged cells. Consequently intensive cell testing needs to be conducted. At APL, new approaches were therefore developed to analyze the electrical, mechanical and thermal behavior, taking into account the deviations of individual cells. In a new type of measurement setup, cells are characterized using laser technology and thermal imaging while being exposed to dynamic load. Simulations are used to determine the influence of parameters such as the state, number and position of deviating single cells on the performance of the overall battery system. The gained insights are combined into an overall system view and validated with battery measurement data during real driving cycles.