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% LiNi 0.6   Co 0.2   Mn 0.2   normalO 2 (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.

The shear stress induced breaking behavior of carbon black (CB) aggregates during the manufacturing process of Li‐ion batteries is investigated via microscale discrete element method (DEM) simulations. The relevant range of shear stress is chosen according to a planetary mixer and cathode slurries with high solid content. Aggregates of different sizes and shapes are modeled using a self‐written algorithm based on the tunable dimension method. Then, suitable models are chosen for representing the solid bridges between the primary particles of the CB aggregates and relevant fluid forces. The results show a correlation between aggregate size and critical shear stress which is required to initiate aggregate fracturing. Furthermore, a change in aggregate shape is linked to applied stress and initial aggregate size and shape. Hence, a recommendation for an efficient disintegration of CB aggregates during the mixing process is made.

A lithium-ion battery (LIB) cathode comprises three major components: active material, electrical conductivity additive, and binder. The combination of binder and electrical conductivity additive leads to the formation of composite clusters known as the carbon binder domain (CBD) clusters. Preparation of a LIB cathode strongly influences the dispersion of the above-mentioned constituents leading to the formation of distinct pore and electrical conduction networks. The resulting structure thus governs the performance of LIBs. The presence of CBD is essential for the structural integrity and sufficient electrical conductivity of the LIB cathode. However, CBD abundance in LIB cathodes leads to unfavorable gravimetrical and volumetrical consequences owing to its electrochemical inertness. Increasing CBD content adds to the weight of the LIBs, thus negatively impacting the energy density. Furthermore, increased electrical conductivity is won at a cost of ionic conductivity as CBD clusters breach the pore networks in the cathode microstructure. The following study establishes a link between the various possibilities of CBD cluster size and fractal dimension that may eventualize during the mixing process of slurry preparation to the resulting microstructural properties and hence to the performance of LIBs by means of idealized cathode geometries. Since the performance determining processes occur at the microstructural scale, which are often very tedious to study via experimental research, the study makes use of spatially resolving microstructural, numerical, simulations. The results demonstrate that the CBD cluster size has a strong influence on the cathode microstructure. The CBD cluster fractal dimension on the other hand displayed a minor influence on the structural properties of the cathode, and the size of the cluster primary particles was shown to be the dominant factor. Finally, performance evaluation simulations confirmed the trends seen in structural properties with changing cluster size and fractal dimension.

A complex interaction between the process design and the properties of carbon black (CB) during dry mixing of cathode material influences the microstructure and thus the performance of the Li‐ion battery. The description of these interactions by means of a coupling of the mixing process simulation and the fragmentation of CB is the focus of this work. The discrete element method provides information about the frequency and intensity of the stress. The change of the CB size distribution is done by the population balance equation. The material strength as well as the fracture behavior are represented with simple models. The calibration of the model parameters is performed using the Nelder–Mead algorithm. The calibrated models provide good agreement with the measurements of the size distributions from experimental investigations. Transfer of the calibrated parameters to other process settings is possible and provides good agreement in some cases. Recalibration of the fracture behavior improves the accuracy of the model so that it can be used as a predictive tool.

In this study, we performed a multi scale characterization of precipitated silica including small angle X ray scat tering (SAXS), analytical (ultra) centrifugation as well as electron microscopy and pore size determination tech niques. Information about the primary particles and their size distribution within the aggregate, the aggregate size and its fractal dimension, as well as mesoscopic bulk properties, e.g. porosity and sediment structure analysis, were put into context. The data obtained here allow a statement to be made about the number of primary parti cles per aggregate and the aggregate structure including pore size distribution and pore inlet diameter. The cor relation of the obtained measurement data with mathematical models allows a deeper understanding of the structure and description of fractal aggregates.