Influence of the Carbon Black Dispersing Process on the Microstructure and Performance of Li‐Ion Battery Cathodes

Abstract

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.

Current and future lithium-ion battery manufacturing

“…The work of cohesion/adhesion between the dry particles results in a special microstructure to allow more access surface on AM particles to contact with electrolyte. The cross-linked-like network formed by the binder and conductive carbon has been proved to increase the conductivity, lower the overall resistance, and improve the electrochemistry performance (Mayer et al, 2019). Liu et al further developed the dry printed anode with a discontinuous PVDF interlayer to enhance the bonding strength between the electrode and collector (Liu et al, 2019)…”

Accelerating Battery Manufacturing Optimization by Combining Experiments, In Silico Electrodes Generation and Machine Learning

“…Indeed, the changes in the volume fraction of the constituting phases were taken here as a metric to evaluate the effect of the applied calender pressure. Nonetheless, it is known that the electrode compression does not only impact the former but also causes particle deformation (or even breakage of the bigger AM particles), 53,54 without overlooking the fact that mesostructural changes are expected to depend on how the CBD phase is distributed throughout the electrode (tuned by the mixing and drying stages [55][56][57] ). Further research to implement results coming from physics-based modelling, together with the experimental data, into the electrode mesostructure generating algorithm are ongoing and will be the core of further reports by our group.…”

Microscale Discrete Element Method Simulation of the Carbon Black Aggregate Fracture Behavior in a Simple Shear Flow

“…These correlations were used to model the aggregates of different size and fractal dimension using a self‐written algorithm; the application of which was previously described by Mayer et al [ 23 ] The algorithm uses the tunable dimension method (TDM) which allows adding primary particles to an existing aggregate without significantly changing its fractal dimension. In this work, the numerical approach for the TDM is shown in Figure 2 .…”

“…The solid content within the cell varies slightly between 45% and 65% depending on aggregate size and fractal dimension. The applied shear stress varies between 3 and 40 kPa according to occurring conditions in a planetary mixer with cathode slurries with high solid contents as used by Mayer et al [ 23 ] The aggregate size range is between 400 nm and 1 μm and with the fractal dimension preset to different values between 1.8 and 2.5. Also the domain is filled with CB aggregates only to isolate the disintegration due to fluid shear forces.…”