Inline Monitoring of Battery Electrode Lamination Processes Based on Acoustic Measurements

Due to the energy transition and the growth of electromobility, the demand for lithium-ion batteries has increased in recent years. Great demands are being placed on the quality of battery cells and their electrochemical properties. Therefore, the understanding of interactions between products and processes and the implementation of quality management measures are essential factors that requires inline capable process monitoring. In battery cell lamination processes, a typical problem source of quality issues can be seen in missing or misaligned components (anodes, cathodes and separators). An automatic detection of missing or misaligned components, however, has not been established thus far. In this study, acoustic measurements to detect components in battery cell lamination were applied. Although the use of acoustic measurement methods for process monitoring has already proven its usefulness in various fields of application, it has not yet been applied to battery cell production. While laminating battery electrodes and separators, acoustic emissions were recorded. Signal analysis and machine learning techniques were used to acoustically distinguish the individual components that have been processed. This way, the detection of components with a balanced accuracy of up to 83% was possible, proving the feasibility of the concept as an inline capable monitoring syste

Simulation Based Approach for High-Throughput Stacking Processes in Battery Production

What are the benefits of simulation-driven design and optimization of stacking processes in battery cell production? This question is addressed within the scope of the paper. This work proposes a method to reduce the effort for model-based design and optimization. Based on three case studies which originate from the development of high-speed stacking processes, this paper illustrates how the relevant loads on the intermediate products are determined with the help of the method. Subsequently, it is shown how the specific material models for battery electrodes and separators are identified, created and validated, as well as how process models are created and process limits are identified and optimized. It was possible to prove how process simulations can be used to minimize the effort required to validate developments and to efficiently determine optimized process parameters for a format and material change in a model-based manner. Consequently, more and more model-based processes should be taken into account during development and start-up in the future.BMBF, 03XP0236A, HoLiB - Hochdurchsatzverfahren in der Fertigung von Lithium-Ionen-BatterienBMBF, 03XP0236B, HoLiB - Hochdurchsatzverfahren in der Fertigung von Lithium-Ionen-BatterienBMBF, 03VP01480, Validierung eines innovativen Verfahrens zur produktivitätsgesteigerten Herstellung von z-gefalteten Lithium-Ionen-Batterien durch eine kontinuierliche Verfahrensführung - KontiBatDFG, 414044773, Open Access Publizieren 2021 - 2022 / Technische Universität Berli

Inline Monitoring of Battery Electrode Lamination Processes Based on Acoustic Measurements

Due to the energy transition and the growth of electromobility, the demand for lithium-ion batteries has increased in recent years. Great demands are being placed on the quality of battery cells and their electrochemical properties. Therefore, the understanding of interactions between products and processes and the implementation of quality management measures are essential factors that requires inline capable process monitoring. In battery cell lamination processes, a typical problem source of quality issues can be seen in missing or misaligned components (anodes, cathodes and separators). An automatic detection of missing or misaligned components, however, has not been established thus far. In this study, acoustic measurements to detect components in battery cell lamination were applied. Although the use of acoustic measurement methods for process monitoring has already proven its usefulness in various fields of application, it has not yet been applied to battery cell production. While laminating battery electrodes and separators, acoustic emissions were recorded. Signal analysis and machine learning techniques were used to acoustically distinguish the individual components that have been processed. This way, the detection of components with a balanced accuracy of up to 83% was possible, proving the feasibility of the concept as an inline capable monitoring system

Investigation of the lamination process for the production of lithium-ion batteries

Gegenwärtig lässt sich eine hohe und stetig wachsende Nachfrage an qualitativ hochwertigen Batteriezellen beobachten, da die Elektrifizierung immer weiter voranschreitet. Gerade der Automobilbereich, aber auch weitere gesellschaftlich relevante Sektoren, setzen verstärkt auf elektrische Energie, für die entsprechende Speicher bereitgestellt werden müssen. Entsprechend groß fällt das Interesse an der Weiterentwicklung der Lithium-Ionen-Batterie selbst und auch ihres Herstellungsprozesses aus. Bei letzterem steht die Entwicklung hochdurchsatzfähiger Prozesse im Vordergrund aktueller Forschungsbemühungen. Einen vielversprechenden Ansatz, eine hochdurchsatzfähige Prozesskette zu schaffen, stellt die Implementierung eines Laminationsprozesses dar, der die Herstellung von stoffschlüssig verbundenen Elektrode-Separator-Laminaten ermöglicht. Dieses neue Zwischenprodukt mit seinen vorteilhaften mechanischen Eigenschaften ermöglicht den Einsatz neuartiger Stapelkonzepte, die den bislang eingesetzten Verfahren hinsichtlich Durchsatz überlegen sind. Weder der Laminationsprozess an sich, noch das Elektrode-Separator-Laminat als sein Produkt sind bislang umfassend erforscht. Das Ziel der vorliegenden Dissertationsschrift besteht darin, Forschungslücken zu diesem Themenfeld zu schließen, indem ein grundlegendes Verständnis über die Wirkbeziehung zwischen den Prozessparametern des Laminationsprozesses und den Produkteigenschaften des entstehenden Laminats aufgebaut wird. Hierzu werden sowohl mechanische als auch elektrochemische Eigenschaften des Laminats und daraus gefertigter Batteriezellen untersucht. Es wird gezeigt, dass über die kombinatorische Wahl relevanter Prozessparameter unmittelbar Einfluss auf die Haftung zwischen Elektrode und Separator im Laminat als zentrale mechanische Eigenschaft genommen werden kann und sich Prozessparameterpaarungen auch auf die elektrochemischen Eigenschaften auswirken. Aus diesen Ergebnissen wird schließlich ein Prozessfenster abgeleitet, in dem mechanisch stabile und elektrochemisch performante Laminate reproduzierbarer Qualität erzeugt werden können. Die Reproduzierbarkeit qualitativ hochwertiger Laminate kann als eine Bedingung betrachtet werden, Lamination auch in der industriellen Batteriezellproduktion einzusetzen. Hierfür ist es – insbesondere in Anbetracht der Neuartigkeit und damit potenzieller Fehleranfälligkeit des Prozesses – notwendig, den Laminationsprozess zu überwachen und die entstehenden Laminate zu kontrollieren. Im Rahmen dieser Arbeit werden inline-fähige Messverfahren entwickelt, vorgestellt und evaluiert, die die Prozessüberwachung sowie Produktkontrolle im laufenden Fertigungsbetrieb ermöglichen. Letztendlich erscheint die Implementierung des Laminationsprozesses in die etablierte Prozesskette zur Fertigung von Lithium-Ionen-Batterien nur dann schlüssig, wenn sie sich auch aus ökonomischer Perspektive lohnt. Daher wird die Untersuchung der technischen Machbarkeit und inline-fähigen Überwachung ergänzt um die Bewertung der Wirtschaftlichkeit einer Integration der Lamination in die Großserienfertigung von Lithium-Ionen-Batterien. Hierbei werden im Rahmen verschiedener Szenarien Voraussetzungen ermittelt, unter denen sich der Einsatz von Lamination wirtschaftlich rentiert. Sind alle drei Anforderungen – technische Umsetzbarkeit von Lamination, Qualitätskontrolle und Wirtschaftlichkeit – erfüllt, ist der Weg geebnet für die Erweiterung der etablierten Prozesskette zur Batteriezellfertigung um den Prozessschritt der Lamination.At present, a high and constantly growing demand for high-quality battery cells can be observed as electrification continues to advance. The automotive sector in particular, but also other socially relevant sectors, are increasingly relying on electrical energy for which appropriate storage devices are required. Consequently, there is a great interest in the further development of the lithium-ion battery itself and also its manufacturing process. With regard to the manufacturing process, the development of high-throughput processes is at the forefront of current research efforts. A promising approach to achieve this goal is the implementation of a lamination process that enables the production of bonded electrode-separator laminates. This new intermediate, with its advantageous mechanical properties, enables the use of novel stacking concepts that are superior to the processes used currently in terms of throughput. Neither the lamination process itself nor the electrode-separator laminate as its product have been extensively researched to date. The aim of this dissertation is therefore to close research gaps in this field by establishing a fundamental understanding of the interdependencies between the process parameters of the lamination process and the product properties of the resulting laminate. For this purpose, both mechanical and electrochemical properties of the laminate and battery cells manufactured from the laminates are investigated. It is shown that the combinatorial choice of relevant process parameters can directly influence the adhesion between the electrode and the separator as the central mechanical property. In addition, the effect of process parameter variation on the electrochemical properties is demonstrated. Finally, a process window is derived from these results in which mechanically stable and electrochemically performant laminates of reproducible quality can be produced. The reproducibility of high-quality laminates can be regarded as a prerequisite for using lamination in industrial battery cell production. For this reason, it is necessary to monitor the lamination process and to control the resulting laminates, especially considering the novelty and thus potential high error rate of the process. Within the scope of this work, inline-capable measurement methods are developed, presented and evaluated, which enable process monitoring as well as product control during production. Ultimately, the implementation of the lamination process in established process chains for the production of lithium-ion batteries only appears conclusive if it is also worthwhile from an economic standpoint. Therefore, the investigation of technical feasibility and inline monitoring is supplemented by an evaluation of the economic viability of integrating lamination into the large-scale production of lithium-ion batteries. Within the framework of various scenarios, conditions are determined under which the use of lamination is economically viable. If all three requirements - technical feasibility of lamination, quality control and economic efficiency- are fulfilled, there is nothing to prevent the established process chain for battery cell production from being extended by the lamination process

Process-Product Interdependencies in Lamination of Electrodes and Separators for Lithium-Ion Batteries

In today’s cell production, the focus lies on maximizing productivity while maintaining product quality. To achieve this, the lamination of electrode and separator is one key process technology, as it bonds the electrode and separator to form mechanically resilient intermediate products. These mechanically resilient intermediates are necessary to enable high throughput processes. Although the lamination process has significant effects on the electrochemical performance of battery cells, it has not been sufficiently researched with regard to its process-product interdependencies. Therefore, this paper addresses the investigation of these interdependencies and proposes three characterization methods (grey scale analysis, high potential tests, electrochemical cycling and C-rate tests). The results of the three methods show that the lamination process with its process parameters (lamination temperature, lamination pressure and material feed rate) has an influence on both the properties of the intermediate product and the cell properties. In conclusion, the knowledge of the process-product interdependencies is essential in order to utilize the advantages of lamination integrated into the process chain and consequently achieve quality-assured cell production

Influence of the Lamination Process on the Wetting Behavior and the Wetting Rate of Lithium-Ion Batteries

In lithium-ion battery manufacturing, wetting of active materials is a time-critical process. Consequently, the impact of possible process chain extensions such as lamination needs to be explored to potentially improve the efficiency of the electrode and separator stacking process in battery cell manufacturing. This paper addresses the research gap of the unexplored effects of lamination on the wetting rate of electrode-separator assemblies in pouch cells. Based on the triangulation of three measurement techniques (gravimetric, optical, electrochemical), a correlation between lamination and wettability of electrode-separator assemblies is experimentally demonstrated, thus providing an important research contribution