Conductive Coatings: Enabling Dry Battery Electrode Manufacturing

The Future of Lithium-Ion Battery Manufacturing: Dry Battery Electrode (DBE) Processing

The lithium-ion battery industry is undergoing a transformative shift with the advent of Dry Battery Electrode (DBE) processing. This innovative approach eliminates the need for solvent-based slurries, streamlining production and addressing both efficiency and environmental concerns. In this blog, we’ll explore how DBE technology is revolutionizing battery manufacturing, the challenges it has faced, and how Henkel’s thin conductive coatings are overcoming these hurdles.

Introduction to Lithium-Ion Battery Electrodes

Lithium-ion batteries are composed of two electrodes, the anode and cathode, separated by a porous membrane. These electrodes play a crucial role in the battery’s performance and longevity by storing and transferring lithium ions during charge and discharge cycles.

Electrodes typically consist of thin metal foils (current collectors) coated with active material particles. Binders and carbon additives are mixed into the coating to enhance mechanical stability and electrical conductivity. Common cathode materials include layered oxides like NMC (Lithium Nickel Manganese Cobalt Oxide) or NCA (Lithium Nickel Cobalt Aluminum Oxide) and olivine structures such as LFP (Lithium Iron Phosphate). Anodes generally contain graphite or graphite-silicon composites.

Traditional Electrode Manufacturing Processes

The majority of lithium-ion battery electrodes are manufactured using slurry-based coating processes. In these processes, active materials and additives are dispersed in a solvent—typically water for anodes or NMP (N-Methylpyrrolidone) for cathodes. The slurry is then coated onto aluminum or copper foils, followed by drying to remove any remaining solvents. The final steps include calendaring to reduce porosity and slitting the electrodes to align with specific cell format requirements.

While slurry-based processes offer control over coating thickness and high-speed production, they rely heavily on solvents, which present environmental and ecological challenges. NMP, in particular, poses reproductive toxicity risks and requires energy-intensive removal processes. Electrode drying and solvent recovery can account for over 25% of the total energy consumption in battery cell production, contributing significantly to CO²emissions.^[1]

The Rise of Dry Battery Electrode (DBE) Manufacturing

DBE manufacturing eliminates the need for solvents, addressing the environmental and energy concerns associated with traditional methods. DBE processes begin with powder mixing, where active materials, carbon additives, and binders (typically PTFE) are combined. The mixture is transformed into a dry film through heat rolling (calendering), and this film is then laminated onto the current collector foil.

Advantages of DBE Processing

What are the advantages to DBE processing?

Energy and CO² Reduction: DBE processes can reduce energy demands in battery cell production by up to 25%, significantly cutting CO² emissions.
Space Efficiency: The elimination of drying ovens can reduce production floor space requirements by up to 60%.
Regulatory Compliance: DBE processes align with regulatory measures limiting NMP production and use.
Performance Improvement: DBE can potentially enable higher energy densities through thicker electrodes.
Cost Savings: Reducing energy and space requirements lowers overall production costs.
Henkel’s Thin Conductive Coatings: A Solution to DBE Challenges

One of the major challenges in DBE processing has been ensuring strong adhesion between dry films and current collector foils. Poor adhesion can lead to processing issues, increased resistance, capacity loss, and reduced battery life. Henkel aims to address this challenge with their innovative thin conductive coatings, which enhance adhesion and conductivity.^[2]

Conductive Coatings in Lithium-Ion Batteries

Conductive coatings play a vital role in enhancing battery performance. These coatings, typically water or solvent-based dispersions of conductive fillers, resins, and additives, are applied to current collector foils to increase surface roughness and improve the interaction between the current collector and the active material layer.

Benefits of Conductive Coatings

Here are some of the benefits of conductive coatings:

Improved Conductivity: Facilitates electron movement within the electrode, reducing electrical resistance.
Enhanced Adhesion: Ensures a stable and durable electrode by adhering well to both the current collector and the active material.
Chemical Protection: Prevents corrosion on the current collector during cell manufacturing and battery operation.

Henkel’s conductive coatings are designed to meet the specific requirements of DBE manufacturing. The technology ensures strong film formation at standard battery operation temperatures and enhances adhesion between the dry film and the current collector during lamination.

Design and Performance Considerations^[2]

Electrochemical Stability: Prevent coating decomposition, which can harm cell performance.
Electrolyte Resistance: Ensure stability against electrolyte dissolution to maintain battery performance.
Durability: Scratch resistance and strong adhesion to the foil for smooth processing.
Sustainability: Water-based formulations without polyfluorinated binders support sustainability goals.

Application Technologies^[2]

Conductive coatings can be applied using slot-die or rotogravure methods, ensuring precise thickness control and uniform surface quality. Gravure coating, in particular, facilitates efficient application at high speeds, maintaining consistent edge management and surface quality.

Enhancing Adhesion and Conductivity^[2]

Henkel’s “active” conductive coating system incorporates a flexible adhesive component, creating a seamless interface between the conductive coating and the dry film. This flexible system increases the adhesive strength between the layers, significantly improving adhesion compared to traditional “passive” coatings.

Conclusion

Technological advancements in conductive coating technology are paving the way for widespread adoption of DBE processes. By eliminating the need for solvent-based slurries, DBE technology offers a more efficient, cost-effective, and environmentally friendly solution for lithium-ion battery manufacturing. These innovative coatings, such as the technology developed by Henkel, ensure strong adhesion and reliable conductivity, enhancing battery performance and longevity.

As the industry continues to evolve, Henkel stands ready to support battery manufacturers in achieving their productivity, quality, performance, and sustainability goals. To learn more about Henkel’s innovation solutions, you can view the full whitepaper on their website.