Authors: Dr. Felipe Wolff Fabris (SKZ), Heiko Oetting (NETZSCH)

The production of battery cells includes a large number of different process steps: starting from the selection of suitable raw materials going all the way to an operational battery system. In the frame of the BATMACHINE project, we are focusing at the mixing and dispersing of the battery slurries, the electrode coating, as well as the subsequent drying and calendaring. Considering the cell production line, each individual step is adapted to the specific employed materials and optimised with regard to the objectives and requirements for the electrode. Therefore, all process steps have to be matched to the battery formulation of the manufacturer and have a direct influence on the performance of the electrical storage system.

Figure 1: Process steps from the selection of raw materials to the operational battery cell (Source: Liu (2021), iScience 24 (4))

Battery slurry mixing – a new concept

One of the key objectives of BATMACHINE project is to develop a slurry mixing/dispersion machinery. The goal would be to make it highly efficient for different slurry formulations, meaning a minimal energy consumption during operations. This is a major challenge, considering the fact that battery slurry formulations contain several components (dry and liquid phases). Specifically, different powders show very distinct particle size and particle-particle interactions. Consequently, this results in different mixing/dispersion intensities, which become required to assure the homogeneous dispersion.

In this context, the BATMACHINE partner SKZ is acquiring and characterising various raw materials. In addition, SKZ is also investigating the produced slurries and evaluating their structure-properties-relationships, depending on the mixing/dispersing form and energy. Furthermore, BATMACHINE partner NETZSCH is developing a new process with a universal modular automated slurry production line. Such production line will use the generated raw materials know-how for an optimal operation and carry out the experiments under different conditions. In order to produce the slurry as quick as possible and in a way that saves resources, the mixing process develops into different stages. Moreover, such mixing stages can also run in parallel.

BATMACHINE slurry mixing objectives

The basic slurry formulation will be provided by the battery manufacturer. BATMACHINE will optimise the process variables and steps to reduce the energy consumption during processing. Furthermore, NETZSCH is also developing and including the on-line / at-line rheology measurement systems. In fact, such measurements will allow a significant increase of the process monitoring and quality, and minimise scrap in a very early process step.

Figure 2: Universal modular automated slurry production machinery (Source: NETZSCH)

Source: Liu, Yangtao; Zhang, Ruihan; Wang, Jun; Wang, Yan (2021): Current and future lithium-ion battery manufacturing. In: iScience 24 (4), S. 102332. DOI: 10.1016/j.isci.2021.102332.