Press Release "FormEL"

  Copyright: © PEM

In the new project "FormEL", the PEM of RWTH Aachen University together with partner institutes continues to conduct research on cost reduction and quality improvement of lithium-ion battery cells induced by cell finalization. The goal is a function-integrated optimization of the battery production process by determining the process-quality relationships.

One of the biggest challenges in battery production is understanding between process and quality parameters. Especially in the cost- and time-intensive process step of cell finalization, great potentials of the lithium-ion battery can be realized by a deep process understanding. In the "FormEL" research project, PEM is working with other research institutes from Münster, Braunschweig and Munich on research into formation and end-of-line (EoL) testing with the aim of achieving functionally integrated overall process optimization of the two process steps. The project is funded by the German Federal Ministry of Education and Research (BMBF) as part of the "Battery 2020" funding initiative with more than two million euros.

In research, only isolated studies have been conducted to date on the influence of process parameters such as temperature, current density, voltage profiles and various materials on the formation and EOL test. Empirical values on the process parameters of industrial cell manufacturing plants are largely unknown. Thus, the formation process represents a multiscale problem. PEM is working on researching this problem in battery production together with the Institute for High Voltage Technology and Electrical Power Systems (elenia) at the Technical University of Braunschweig, the Institute for Energy and Systems Process Engineering at the Technical University of Braunschweig (InES), the Münster Electrochemical Energy Technology Research Center (MEET) Battery Research Center at the Westphalian Wilhelms University of Münster and the chair for Electrical Energy Storage at the Technical University of Munich (EES) within the "FormEL" project.

In the project, process-quality relationships are used to develop detailed models and optimize the two process steps, with the aim of merging them in a functionally integrated way. For this purpose, physical models will represent the electrochemical processes during the formation and the EOL test in order to derive interactions and predictions regarding the cell properties depending on the formation procedure. In addition, a modular carrier concept will be developed to combine the forming process and the EoL test, which can cover different battery cell variants battery cell dimensions and formats with little changeover effort and includes the necessary measurement and control technology. These optimization approaches will subsequently be analyzed and validated by means of experimental investigations.

Reduction of process costs and time with simultaneous increase of cell quality

By identifying the process-quality relationships and model-based optimizations of the individual processes, the aim is to reduce process time. The faster process time of the function integration leads on the one hand to a reduction of the energy costs per cell and on the other hand enables the increase of the production throughput, which reduces the fixed costs per cell. The necessary measurement technology for the forming process, including the EoL test, is to be implemented in a flexible product carrier for several cells. This offers further cost saving potential and is suitable for the use of future cell generations due to its flexible design. The expertise gained in the project is not only of great importance for current cell generations in order to increase the performance of the battery cells, but also for future battery cell generations in order to improve the start-up problems through intelligent linking of the parameters.

In this context, "FormEL" builds on expertise from projects already completed "OptiZellForm" and "EffiForm" and thus uniquely bundles all the expertise of the institutes of previous projects under one roof. The findings on processes from the two projects serve as a basis and input for the "FormEL" project. In OptiZellForm, it was shown that a reduction in process duration can be achieved by adjusting the ambient temperature and lightly pressing the battery cells during forming. In EffiForm, it was determined that experimental variations in electrolyte additives as well as electrode porosities did not have a limiting effect on the high current capability of the formation. Instead, a shift of the formation to subsequent cycles was found. The results obtained and findings from the "FormEL" project are to be transferred to the "Fraunhofer Research Institution for Battery Cell Production FFB" in Münster, where they will be used to improve processes.