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How Improved Dispersion Enhances Slurry
Viscosity, Pumping, and Solids Loading
Achieving proper dispersion in a battery slurry is essential for both product performance and process efficiency. When comparing formulations with and without a dispersant, it is important to keep all testing conditions stable so the impact on viscosity, stability, and processability can be accurately evaluated.
Understanding Viscosity Changes with Dispersants
One of the most immediate effects of adding a dispersant is a shift in viscosity. While some formulators initially worry that reduced viscosity at low shear rates may make the slurry too fluid - for example, causing it to run on the current collector - this change is actually connected to improved dispersion. Better particle separation lowers viscosity naturally, reflecting a more uniform and stable slurry.
Monitoring viscosity across the full shear range ensures that the slurry remains within acceptable process limits, while still benefiting from the improved flow behavior created by effective dispersion.
Liquid‑Like Pumping Behavior with Improved Dispersion
Once dispersion is achieved, the slurry often shows a transformation in its viscoelastic behavior. In well‑dispersed systems, such as those prepared with Vanisperse LI, the loss modulus exceeds the storage modulus across the entire shear spectrum. This indicates that the slurry behaves fully as a liquid, not as a viscoelastic solid.
This liquid‑like behavior offers several processing advantages:
- Easier pumping - The slurry moves smoothly from reservoir to slot‑die without needing elevated pressure.
- More stable flow - There is less risk of pulsation, clogging, or uneven transitions between stages.
- Lower energy demand - Equipment doesn’t need to work as hard to transfer material.
For some applications, this level of fluidity may initially seem too low in viscosity. However, rather than being a drawback, it represents a key opportunity.
A Clear Opportunity: Increasing Solids Loading
When dispersion reduces viscosity and improves pumpability, it creates room in the formulation to increase slurry solids without introducing processing challenges. Higher solids can deliver:
- Greater mass loading and improved energy density
- Reduced drying time and lower energy consumption
- Higher overall production throughput
The ability to raise solids content without compromising flow or coating stability is one of the most valuable benefits of achieving proper dispersion.
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Read our Publication: "Debundling of SWCNTs using a Non-Toxic, Low Carbon Footprint Dispersant"
Abstract
A fully aqueous, N-methyl-2-pyrrolidone–free strategy for debundling single-walled carbon nanotubes (SWCNTs) is reported using the renewable dispersant Vanisperse® LI. Dispersions at 2 mg mL−1 were subjected to probe ultrasonication at 0.3 W mL−1 and evaluated using oscillatory rheology. Complex viscosity (η*) exhibited a transient maximum (~75 min) consistent with the formation of a percolated fibrous network, followed by a decline as debundling progressed. An optimum dispersant coverage of ~1.5 mg m−2 minimized η*, while overdosing likely induced multilayer adsorption and bridging seen by a rapid increase in η*. A two-stage centrifugation at 10,000× g yielded storage-stable suspensions of debundled SWCNTs without ultracentrifugation. SEM confirmed substantial debundling into thin fiber-like bundles. By formulating a dispersion with a dispersant that has a significantly lower cradle-to-gate carbon footprint than both fossil-based and bio-based alternatives such as CMC, this work presents a more sustainable approach to producing debundled SWCNT dispersions for advanced material applications.
Technical Bulletin: Dispersion of Carbon Nanotubes with Vanisperse LI
Borregaard’s bio-based battery additives are designed for use in water-based electrode slurries and to stabilize aqueous carbon nanotube (CNT) dispersions. Obtained from sustainably sourced wood, our products are non-toxic, environmentally friendly, and highly effective.
Vanisperse LI provides a uniquely sustainable alternative and affords a lower CO2 footprint than petroleum-derived additives. Efficient dispersion of CNTs is critical for achieving uniform electrode composition and optimal battery performance. Sustainable water-soluble dispersants are essential to de-agglomerate CNTs in water, preventing the hydrophobic carbons from reforming agglomerates.