Enhancing Battery Slurries: Efficiently Decreasing Mixing Time and Energy with an Intensive Mixer

The high demand for lithium-ion batteries is undeniable. According to current studies, the demand for cars, portable devices, and energy storage is expected to increase by more than ten times by 2030. To meet the rising demand, ever larger and more efficient battery factories are required.

The mixing process is the first step in the production of lithium-ion batteries. It is crucial for the quality of the battery and has one of the greatest impacts on the cell's performance. In the mixing process, active material, binder, and conductive additives are mixed with a dispersion agent like water or solvent to form a slurry. Mixing tools must distribute the particles homogeneously throughout the entire volume.

These mixing tools must also fulfill another basic requirement. When producing electrode slurries for lithium-ion batteries, it is be necessary to break up potential agglomerates and avoid local material accumulation on a microscopic level.

Currently, planetary mixers are preferred for mixing battery slurries for cathode and anode. But is this really the best and most efficient method for mixing battery masses? An even more efficient alternative would be an intensive mixer (PMD-Mixer), which consists of two mixing tools.

The primary mixing tool disperses, homogenizes, and wets the material. The cavitation disc is eccentrically arranged and gradually travels up and down through the dispersing container. A secondary mixing tool continuously transports the material to the primary mixing tool in the dispersing zone. The combination of both mixing tools creates a vortex in the container—imagine a mini-tornado with high laminar streaming profile—providing complete mixing throughout. This vortex enables efficient dispersion of the material with up to 50% lower energy consumption and allows for high material dosing. Another time reducing factor is the fast powder feeding. In approximately 60 seconds, one complete Bigbag containing approximately 1 tonne of material can be added dust free using a PMD 5000 or larger mixer.

Compared to conventional planetary mixers, which require about 4 hours to produce an anode slurry, an intensive mixer only takes about 1–2 hours, resulting in enormous time and cost savings. Another advantage is the easy scalability up to 20,000 L mixing volume and a corresponding increase in production at lower investment costs. The cylindrical–conical container geometry of the intensive mixer allows for a partial batch processing of at least 25%, enabling a more flexible process design. Automation also plays a major role. The intensive mixers can be equipped with a fully automatic cleaning system (CIP, Cleaning In Place) and have an automatic dosing and control system, reducing the active personnel effort.

The Fraunhofer Research Facility Battery Cell FFB is building a center for the development of modern and scalable battery cell production in Münster. With the second construction phase of the "FFB Fab," Fraunhofer FFB plans to commission a large-scale production line for battery cell production. The production will be flexible, which means that battery manufacturers and industrial companies along the entire value chain of battery cell production can test all or selected process steps and optimize them for their purposes.

FFB commissioned NETZSCH to provide a complete mixing system for this major undertaking, including intensive mixers for large-scale and flexible production. This is an important milestone for NETZSCH to further establish itself in this growing market and contribute to the energy and mobility transition. Through cutting-edge expertise in grinding, dispersing, and more, NETZSCH is helping to improve the energy efficiency, sustainability and reliable scalability of manufacturing for battery cell production on a smaller footprint.