Battery cell production is a complex process chain with interlinked manufacturing processes. Calendering in particular has an enormous influence on the subsequent manufacturing steps and final cell performance. However, the effects on the mechanical properties of the electrode, in particular, have been insufficiently investigated. For this reason, the impact of different densification rates during calendering on the electrochemical cell performance of NMC811 (LiNi_0.8Mn_0.1Co_0.1O₂) half-cells are investigated to identify the relevant calendering parameters. Based on this investigation, an experimental design has been derived. Electrode elongations after calendering in and orthogonal to the running direction of the NMC811 cathode are investigated in comparison with a hard carbon anode after calendering. Elongations orthogonal to the machine direction are observed to have no major dependencies on the compaction rate during calendering. In the machine direction, however, significant elongation occurs as a dependency of the compaction rate for both the hard carbon anode and the NMC811. In addition, the geometric shape of the NMC811 electrodes after separation into individual sheets is investigated with regard to different compaction rates during calendering. It is shown that the corrugations that occur during calendering are propagated into the single electrode, depending on the compaction rate.

Calendering is an essential process step in battery cell production. By selective compaction of the material, the performance of the battery cell can be optimized. During processing, corrugations can occur in the machine direction, which are characterized in this article in relation to the material systems LiNi_0.8Mn_0.1Co_0.1O₂ (NMC811) and LiNi_0.6Mn_0.2Co_0.2O₂ (NMC622) as well as the rate of compaction and the web tension. It is shown that the corrugations are strongly dependent on the rate of compaction. The material system and the web tension show a weaker influence on the corrugation characteristics. Subsequently, single electrode sheets are cut from the coils and their geometry is investigated. It is shown that the corrugation hardly propagates further into the single electrodes, which is explained with the storage time of the electrodes. Rather, the coil bending strongly influences the electrode sheet geometry. It is shown that the position of the conductor tab also has an important influence.

The transformation toward electromobility presents a significant challenge to the battery cell production processes. It is, therefore, necessary to establish efficient and robust operations and machines to meet the forecasted demand for manufactured cell capacity. Currently, the development and ramp‐up phases of production machines, especially for cell stack assembly, are characterized by high material scrap rates and large personnel expenses. Aspects such as the web tension of electrodes or separator materials during separation and stack assembly have a significant influence on the subsequent intermediate product properties, and therefore present a key challenge. Herein, the optimal methodology for the web tension control of electrode materials is determined via a model‐based approach by the means of a digital twin. The focus is hereby set on a production machine for the flexible cell stack assembly. Appropriate control methods are implemented and validated on the real system, thus reducing material scrap rates and overall costs. The control of the web tension by means of an unwinder and material storage was found to be optimal on the basis of the model and confirmed experimentally.

Batteriekalander werden aktuell manuell, erfahrungsbasiert und zeitintensiv iterativ beim Start einer neuen Produktionskampagne eingestellt und bei Bedarf während der Produktion nachjustiert. Bei einer variantenreichen und agilen Produktion tritt dieser Anlaufprozess im Gegensatz zu einer auf ein Produkt spezialisierten Großserienproduktion vermehrt auf. Ein Anlagen- und Automatisierungskonzept für einen schnelleren Produktionsanlauf von Batteriekalandern wird im Folgenden vorgestellt. Battery calenders are currently set manually, experience-based and time-intensively iteratively at the start of a new production campaign and are readjusted as required during production. In a variant-rich and agile production, this start-up process occurs more frequently in contrast to a large-scale production specialized on one product. A plant and automation concept for faster production startup of battery calenders is presented below.