Improving Battery Performance and Reducing Mixing Time with NETZSCH Planetary Mixer PMH

Mixing Time & Energy Saving

Reducing Mixing Time

During validation tests, NETZSCH reduced the mixing time significantly by a factor of 2 for anode mixing and factor 3 of cathode mixing. The NETZSCH Planetary Mixers (PMH) mixed the slurry in 120 minutes (Anode) and 160 minutes (Cathode) and delivered even better-quality performance. So, why were the NETZSCH Planetary Mixers so much better, and how does a Planetary Mixer work?

Improved Performance Through Enhanced Kneading Phase in the Mixing Process

Recent tests have shown significant improvements in battery performance due to the optimized kneading phase during the mixing process with the NETZSCH PMH. A more homogeneous distribution of material is achieved by kneading which leads to the following advatages:

• Higher Performance: The uniform mixing of components results in better material connectivity, enhancing the overall efficiency of the battery. This ensures that energy is transferred more effectively, leading to increased capacity and longer battery life.
• High Charge Percolation: The improved homogeneity also facilitates higher charge percolation within the electrode structure. This allows for more efficient charge transport, reducing resistance and enabling faster charging cycles without compromising battery stability.

These improvements highlight the critical role of a well-executed kneading phase, showing clear advantages in terms of both performance and energy management.

Silicon Anodes in Future Batteries

Addressing Challenges in Mixing and Hydrogen Formation

Silicon anodes are gaining increasing interest for future batteries due to their superior performance potential. However, conventional planetary mixers often introduce problems during the mixing process, particularly due to the high shear forces they generate. These forces can fracture the sensitive Graphite-Silicon-Composite, leading to unwanted side effects such as hydrogen formation.

Conventional planetary mixers, which rely on high-shear dispersion discs (Figure 7, left), can damage crucial components like binders or active materials. This results in compromised battery performance and material degradation. In contrast, NETZSCH mixing tools are specifically engineered to minimize shear forces while enabling a softer and more controlled kneading process. This design allows the mixer to operate at higher speeds without damaging the binder structure of the battery slurry or triggering hydrogen production.

Another practical example of the benefits of advanced mixing techniques can be seen in the preparation of water-based anode slurries containing carboxymethylcellulose (CMC), a polymer with long chains and high molecular mass. Conventional planetary mixers often exert excessive mechanical stress on these polymer chains, causing fragmentation. This leads to undesirable changes in slurry viscosity, such as shear thickening, which renders the slurry unsuitable for subsequent coating processes.

In contrast, NETZSCH’s innovative mixing tools apply a gentler kneading action that preserves the integrity of CMC chains. This approach maintains consistent slurry viscosity, ensuring homogeneous mixing and producing a uniform coating of the active material. The result is a high-quality slurry that supports improved battery performance without the risks associated with conventional high shear mixing methods.

From Lab to Gigafactory

Scalable Mixing for Every Stage

To accelerate the development of new battery chemistries, the NETZSCH PMH planetary mixer is available in a range of sizes, from laboratory to pilot and full-scale production models. A key advantage of the NETZSCH mixers is the consistent ratio of vessel diameter to mixing tools across all machine sizes. This uniformity ensures seamless and efficient scaling from one machine size to the next, enabling faster transitions during the development process.

Additionally, our dedicated battery team and state-of-the-art battery laboratory provide expert support, assisting customers in developing and optimizing cell chemistry to meet their performance goals.

Flexibility

However, the PMH is not limited to a single technology. Its special design and high flexibility in changing mixing tools allow the planetary mixer to be used for various other applications in the battery industry, ensuring process security. One mixer or plant can cover multiple applications, including:

• Different cell chemistry with fluctuations of the solid content (e.g. LFP, LMFP, NMC, ...)
• Mixing of solid-state batteries with high viscosities
• Production of thermal insulation material for battery modules
• Fast mixing of dry battery electrodes without any solvent, with flexible change of geometries
• Sodium-ion batteries

Depending on the application, the mixing tools can be changed in minutes by the customer and no service is needed.