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Lithium‐ion battery cells with high‐energy density and good fast charging properties are subject of current research. One approach to achieve high‐energy densities is the use of higher mass loadings. The challenges of these so called "thick" electrodes are transport limitations: lithium ions cannot reach all layers of the electrode, which results in a drop of performance. Possible concepts to overcome these limitations are the use of different active materials (silicon oxide, graphite, and hard carbon (HC)), and a two‐layer coating of the anode to create a defined pore network, which reduces the ionic resistance and ensure better fast charging capability even at higher mass loadings (8 mAh cm−2). It could be demonstrated that by using a two‐layered anode with HC in the upper layer, the electrical conductivity could be increased by a factor of 10 compared to the reference anode. Furthermore, the interporous HC leads to a capacity retention increase up to 20% with no loss of capacity at moderate C‐rates and a low electrode density. This can be explained by the low tortuosity that results in additional conductive paths for the ions through the coating, reduces the ionic resistance, and ultimately enables faster lithiation of the anode. [ABSTRACT FROM AUTHOR]

Electrodes are usually calendered to enhance the energy density and improve the electrochemical cell performance. However, low porosities can compromise these two important features. To achieve the optimum porosity, a comprehensive process control is of major interest. This study further develops a Heckel‐based compaction model considering the impact of the roll temperature and discusses the effect of the composition. Increasing the temperature of the roll linearly decreases the achievable coating porosity and the line load effort due to the rise of the elastic deformability of the thermoplastic binder PVDF. Reduced contents of simultaneously less‐distributed additives increase the achievable coating porosity. Furthermore, the poor distribution is the main factor for lower line load efforts with lower additive contents. Moreover, the adhesion strength of the coating improves with increasing the temperature of the rolls due to the thermal rising of the elasticity of the binder. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

The post‐drying of electrodes and separators for lithium‐ion batteries just before cell assembly aims at reducing the water content in the cells below a critical value. This is important as the remaining water can lead to cell degradation and thus cause a safety risk. In addition, it can impede the formation of an effective solid electrolyte interface. Nevertheless, the post‐drying of lithium‐ion battery electrodes and separators is still poorly investigated. Considering this, three different post‐drying procedures are investigated on pouch cells and compared with the non‐post‐dried state. The remaining water contents are measured via coulometric Karl Fischer Titration and correlated to the resulting electrochemical performance. Surprisingly, the most intensely post‐dried cells show the worst electrochemical performance despite reaching the lowest water content. In contrast, the mildest post‐dried cells, which show the highest water content, achieve the best electrochemical performance. Further analyses show that extreme post‐drying can cause irreparable damages within the electrode structures. Therefore, a good electrochemical performance is not only guaranteed by low remaining water content but also, in particular, by gentle post‐drying. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

The influence of the dispersion process and the carbon black (CB) particle size on the resulting structure and, hence, on the properties of lithium‐ion battery cathodes is investigated. N‐methyl‐2‐pyrrolidone‐based cathode slurries with 95.5 wt% LiNi0.6 Co0.2 Mn0.2 O2 (NCM622) and a high mass content (82.5 wt%) are processed in a planetary mixer PMH10 from NETZSCH with varying high‐speed stirrer tip speeds. Particle size analyses are carried out to measure the CB particle size at different time steps of the dispersion process. The resulting cathodes are characterized to determine mechanical and electrical properties. The microstructure of chosen electrodes is reconstructed and quantified by focused ion beam/scanning electron microscopy tomography and correlated with experimental data. In addition, discrete element method simulations are used for a deeper understanding of the dispersion process and breakage of CB aggregates. Correlations between process, structure, and properties of lithium‐ion battery cathodes are revealed. [ABSTRACT FROM AUTHOR]

Electrode manufacturing requires multiple process steps, e.g., dispersing and coating. In‐between these steps, intermediate products have to be transferred, stored, and handled. Especially for the development of new active materials or electrode formulations, the variety of parameters that need to be screened is enormous. In addition, these materials are initially tested in small batches, and it is not always possible to upscale the used processes. To evaluate the performance of different materials or differently processed materials, test cells are assembled. This usually requires manual work procedures, which are inherently sensitive to variations and untraceable errors. If the stochastic flaws are large enough, the effects of process variations are covered by these. It is therefore important to increase reproducibility in all process steps. Herein, new concepts for electrode production and automated sample preparation for highly reproducible production and more effective electrode development and screening of parameters are presented. A combined grinding and dispersion process for the production of silicon‐based anodes and an automated assembly system for efficient testing is presented. The processes are supported by methods of data mining to collect process data, ensure high reproducibility, and support research on new active materials. [ABSTRACT FROM AUTHOR]

The influence of the solid content is investigated for cathodes with nickel cobalt manganese oxide (NCM) as an active material during the continuous dispersion in a twin‐screw extruder as well as during the coating and drying processes. Rheological and particle size distribution analyses are carried out to characterize the suspensions. Specifically, mechanical, structural, and electrochemical properties of the manufactured electrodes are determined. The presented results show that an increase in the solid content of the electrode suspension during the extrusion process results in a higher carbon black (CB) dispersion degree due to a higher energy input. At solid content above 80 wt%, delamination of conductive graphite and deposition of CB onto the active material occur. Furthermore, it is proved that within a range of 70–75 wt% solid content, the mechanical, conductive, and electrochemical performances can be enhanced. [ABSTRACT FROM AUTHOR]