Realization and analysis of jet-based direct mixing gas phase agglomeration for the formation of hetero-agglomerates with new properties

Project Leader :

Prof. Dr.-Ing. Harald Kruggel-Emden
Berlin Institute of Technology

Prof. Dr.-Ing. habil. Eberhard Schmidt
University of Wuppertal 

The overall aim of the research work is to contribute to the development of new particulate products based on hetero-agglomerates formed in the gas phase. As part of the first funding period, the Kruggel-Emden group at the Technische Universität Berlin and the Schmidt group at the University of Wuppertal developed, implemented and simulatively analyzed a jet-based process. This process, which should enable the formation of hetero-agglomerates in sufficient quantity and quality, comprises three steps. In the first step, the various primary particles are dispersed and dosed as part of a carrier gas stream. In a second step, the jets interact with the various primary particles and contact occurs, enabling the formation of hetero-agglomerates. In a third step, the products formed must be removed from the contact zone in a controlled manner.

The process developed and modified during the first funding period is to be used in the second funding period for the production of cathode materials for all-solid-state batteries (ASSB). The focus is on investigating the influence of various process parameters on the mixing and structuring of ASSB cathodes in order to increase process efficiency and the quality of the composites produced. The aim is not only to optimize the existing process, but also to understand the relationship between the investigated process parameters, the resulting microstructures and the functional properties (electron and ion transport). By improving the homogeneity of the mixtures, the interfacial resistances within the cathode material are to be reduced, thereby increasing the performance of the battery materials. The necessary investigation of the process and the resulting hetero-agglomerates is carried out experimentally, e.g. using offline imaging techniques (SEM-FIB, EDX), and simulatively using a coupled DEM/CFD approach. The electrochemical properties such as the electronic and ionic conductivity of the composites are also investigated both experimentally in a measuring cell and simulatively using a voxel-based microstructure model.

In addition, the process is to be intensified by means of bipolar, triboelectric charging of the primary particles as part of the dispersion process. For this purpose, homo-agglomerates, which undesirably contain an increased number of particles of one material, are to be separated from the well-mixed, electrically almost neutral hetero-agglomerates in an electrostatic separator. The expected improvement in the material function of the composites is to be investigated simultaneously. The process of electrical charging and electrostatic separation will also be analyzed and designed using suitable DEM/CFD simulations.