Microstructural characteristics of lithium‐ion battery cathodes determine their performance. Thus, modern simulation tools are increasingly important for the custom design of multiphase cathodes. This work presents a new method for generating virtual, yet realistic cathode microstructures. A precondition is a 3D template of a commercial cathode, reconstructed via focused ion beam/scanning electron microscopy (FIB/SEM) tomography and appropriate algorithms. The characteristically shaped micrometer‐sized active material (AM) particles and agglomerates of nano‐sized carbon‐binder (CB) particles are individually extracted from the voxel‐based templates. Thereby, a library of roughly 1100 AM particles and 20 CB agglomerates is created. Next, a virtual cathode microstructure is predefined, and representative sets of AM particles and CB agglomerates are built. The following re‐assembly of AM particles within a predefined volume box works using dropping and rolling algorithms. Thereby, one can generate cathodes with specified characteristics, such as the volume fraction of AM, CB and pore space, particle‐size distributions, and gradients thereof. Naturally, such a virtual twin is a promising starting point for physics‐based electrochemical performance models. The workflow from the commercial cathode microstructure through to a full virtual twin will be explained and assessed for a blend cathode made of the two AMs, LiNiCoAlO2 (NCA) and LiCoO2 (LCO).

The microstructure of lithium-ion battery cathodes rules their performance. However, the production of a variety of cathodes with different microstructures through laboratory experiments is very expensive with respect to costs and time. Thus, model-based simulation approaches, i.e., virtual microstructures generated and analyzed on a computer, have become an important tool for microstructural optimization. In this work, tools for the generation of realistic yet virtual microstructures are presented. Basically, three dimensional reconstructions of cathode microstructures are established by FIB tomography, and the individually shaped particles of the active material phase as well as the carbon black are extracted. A representative set of extracted particles is used to create structures with specified characteristics, such as e.g. the desired mass content of active material and conductive additive or specific particle size distributions. In combination with performance models, a preselection of promising design concepts can be conducted. The complete workflow from the generation of realistic virtual microstructures based on 3D reconstruction via FIB tomography towards the simulation of discharge curves will be shown using the example of a commercial blend cathode consisting of the two active materials LiNiCoAlO2 (NCA) and LiCoO2 (LCO). Figure 1

No abstract