The global demand for efficient batteries is rapidly increasing, especially on account of electromobility. However, production is subject to high cost pressure, with electrode manufacturing representing one of the largest cost factors. The conventional wet-chemical process necessitates the use of slurries containing organic solvents that have to be processed in large energy-intensive dry ovens up to one hundred meters long. This is a real competitive disadvantage for countries such as Germany where energy prices are high. It is therefore necessary to develop innovative electrode production approaches which do not involve solvents but also reduce production costs.

DRYtraec: Revolutionary Dry Coating Technology

DRYtraec, the dry transfer electrode coating process developed by Fraunhofer IWS, is a groundbreaking technology that fundamentally changes the previous battery electrode production method and offers benefits through higher efficiency and lower costs.

• Active material, carbon black, and a special fibrillatable binder are processed to form a dry mixture
• Calender rollers compact the mixture mechanically and a fibril network is formed
• “Dry Transfer Electrode Coating” (DRYtraec): Direct transfer of the resultant film from the film-forming roller to metal foil
• Stabilization through mechanical support for rollers or metal foil leads to high production speeds
• Tandem coating with at least four rollers allows simultaneous electrode coating on both sides

This method makes the process much more efficient by not only eliminating energyintensive drying, but also substantially reducing the amount of space required for production systems. Continuous processing also minimizes machine failures thanks to lower mechanical loads. Dr. Benjamin Schumm, Head of the Particle Technology Department, highlights the advantages: “We recognized at an early stage that dry coating not only reduces costs, but also produces electrodes with beneficial electrochemical properties. With DRYtraec, we have developed a proprietary technology which is making a major contribution towards the industrialization of dry coating.”

DRYplatform: Expansion of R&D Capacities

In order to promote the industrialization of DRYtraec, the investment project DRYplatform (FKZ 03XP0437) was initiated with the support of the German Federal Ministry of Education and Research (BMBF). This 3.7 million euro initiative is extending the infrastructure for industrial application research and completing the R&D program by:

• Systems engineering for scaled powder pre-treatment: Optimized material mixing through extrusion and intensive mixers
• Coating technology: Three prototype units for different material and process requirements, equipped with high-precision dosing, coating, and cutting systems for continuous electrode production
• Measuring technology: Extensive characterization possibilities for powder, coatings and electrodes, tailored to dry coating for purposeful analysis
• Dry-air technology: Innovative supply of dry air with a multi-room, dry-air microenvironment for flexible energy-optimized processing of moisture-sensitive materials and efficient particle filtering

This infrastructure supports the entire value chain from material manufacturers and systems manufacturers through to cell producers. The research results are specifically transferred to industrial applications. Dr. Holger Althues, Head of the Battery Materials Department, emphasizes: “As a scalable and adaptable electrode production method, DRYtraec is an absolute key technology for batteries in future. The process is not limited to a single cell chemistry – it is suitable for lithium-ion batteries, lithium-sulfur batteries and solid-state batteries alike.”

Special emphasis is placed on the transfer of laboratory results at an early stage to application-related prototype cells in order to evaluate the practical relevance of the developed solutions. A large number of publications in renowned scientific journals and an extensive patent portfolio underline the high innovation level of the work. The technology is transferred to industry through:

• R&D projects with partners along the value chain (development of materials, components, processes, and systems, as well as manufacturing of prototype cells)
• Licensing of patents/IP
• Young, highly qualified scientists
• Know-how transfer by means of publications and events such as the Dry Coating Forum and the Li-S Workshop

One unique feature is the Dry Coating Forum, the world‘s leading specialized conference for dry coating. This platform connects industry and science in order to exchange the latest findings and speed up industrial applications.

From Material to Cell with DRYtraec

The combination of DRYtraec and DRYplatform is an ideal basis for the further development of efficient and sustainable battery production technologies. Solvent-free processing represents a decisive advantage, especially for next-generation batteries  such as solid-state cells and lithium-sulfur cells. The research team headed by Dr. Benjamin Schumm and Dr. Holger Althues is concentrating more on transferring its innovative research directly to industrial applications – a key strategy for competitive battery production in Germany and Europe.