The increasing relevance of automotive lithium‐ion battery cells spotlights the importance of economic production in a high quantity. In this context, production technology for large battery formats is of great relevance. Therefore, it is necessary to identify effects on important cell properties, and based on this, develop an understanding of the interaction between process parameters and product properties. Large‐format cells are not comprehensively examined, particularly, in a large sample size, analyzing cell properties in terms of distributed values. Hence, there is so far no statistical data concerning large‐format batteries and their distributed discharge capacity and self‐discharge. For this reason, and in contrast to other studies, the scope of this work is to investigate a large sample size of 79 industrial‐scale 9 Ah battery cells to ensure statistical relevance and generate distributed data of cell properties. For this purpose, a large number of cells are produced and extensively electrochemically investigated. Subsequently, the essential parameters are correlated with the electrode parameter of carbon black particle size. Hence, the foundation for this process–product–property relationship is laid.
The recent development of individual mobility is characterized by a resource‐saving and environmentally friendly technology policy. Electromobility has the greatest potential to meet these demands. Due to the high volumetric power density at both the cell as well as the battery levels, pouch cells are addressed as a target cell format. As a separation of the electrodes is absolutely necessary for this cell design, the separation of the electrodes constitutes a basic operation of the pouch cell production. The established separation methods, such as die and laser cutting, are compared in this work with regard to their physical cutting‐edge quality. For reproducible evaluation, the occurring cutting‐edge characteristics are defined to clearly describe the quality of the separated electrode. Furthermore, the influence of the photonically and mechanically produced cutting edge on the electrochemical performance is presented. The results show that the delamination of the active materials and the bending of the collector and the metal spatter have the greatest influence on the electrochemical performance of the cell.
Due to the increasing demand for high-performance cells for mobile applications, the standards of the performance of active materials and the efficiency of cell production strategies are rising. One promising cell technology to fulfill the increasing requirements for actual and future applications are all solid-state batteries with pure lithium metal on the anode side. The outstanding electrochemical material advantages of lithium, with its high theoretical capacity of 3860 mAh/g and low density of 0.534 g/cm3, can only be taken advantage of in all solid-state batteries, since, in conventional liquid electrochemical systems, the lithium dissolves with each discharging cycle. Apart from the current low stability of all solid-state separators, challenges lie in the general processing, as well as the handling and separation, of lithium metal foils. Unfortunately, lithium metal anodes cannot be separated by conventional die cutting processes in large quantities. Due to its adhesive properties and toughness, mechanical cutting tools require intensive cleaning after each cut. The presented experiments show that remote laser cutting, as a contactless and wear-free method, has the potential to separate anodes in large numbers with high-quality cutting edges.
Laser cutting is a promising technology for the singulation of conventional and advanced electrodes for lithium-ion batteries. Even though the continuous development of laser sources, beam guiding, and handling systems enable industrial relevant high cycle times, there are still uncertainties regarding the influence of, for this process, typical cutting edge characteristics on the electrochemical performance. To investigate this issue, conventional anodes and cathodes were cut by a pulsed fiber laser with a central emission wavelength of 1059–1065 nm and a pulse duration of 240 ns. Based on investigations considering the pulse repetition frequency, cutting speed, and line energy, a cell setup of anodes and cathodes with different cutting edge characteristics were selected. The experiments on 9 Ah pouch cells demonstrated that the cutting edge of the cathode had a greater impact on the electrochemical performance than the cutting edge of the anode. Furthermore, the results pointed out that on the cathode side, the contamination through metal spatters, generated by the laser current collector interaction, had the largest impact on the electrochemical performance.
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