MultiEx

Motivation

The production of lithium-ion battery cells is characterized by complex interrelations between specialized production processes, periphery and technical building services. The technologies in the production system have different technology readiness levels. This increases the complexity of the production system. Interactions between process parameters and other parameters are not well known so far. An understanding of these interrelations is necessary in order to improve planning and operation of a battery cell production line towards more efficient and more productive battery production.

Project description

MultiEx deals with the simulation-based optimization of the extrusion process for lithium-ion battery cathode suspensions. Experiments and multi-scale simulations will be performed to optimize the process with regard to suspension quality, improved screw configurations and high throughput rates. Experimental investigations in previous projects have shown that the distribution of the conductivity additive within the electrode structure decisively influences the performance of the manufactured battery cell. This can make a valuable contribution to optimizing the conductive carbon black structure with regard to increased energy and power density. For this purpose, a process route with dry pre-structuring of the carbon black with active materials is investigated. Extensive simulative studies with the aid of the discrete element method (DEM) offer a flexible and cost-effective possibility to investigate the dry mixing process and the influence of the relevant process parameters. The results of the dry mixing process form the basis for the subsequent continuous wet dispersion in an extruder. Microscale (DEM) and macroscale (CFD) simulations are performed to gain a profound understanding of the dispersion process. From the results of the simulations on the microscale, kinetic specifications can then be derived which mathematically describe the dynamic processes of the carbon black digestion as a function of the forces acting during the mixing process. At the same time, macroscopic simulations using CFD investigate the flow conditions prevailing within the extruder geometry. Finally, both scales are coupled by means of population balances. This provides important information about the stress on the carbon black in the suspension and finally about the particle size that can be achieved with given process parameters.

Contact:

Prof. Dr.-Ing. Hermann Nirschl (KIT)
hermann.nirschl(at)kit.edu