Fraunhofer IWS scientists have developed a new dry electrode coating process for environment-friendly battery production.
According to the scientists, the new IWS technology saves energy and eliminates toxic solvents as the electrodes of the energy storage cells are coated with a dry film instead of liquid chemicals.
Most German automakers continue to purchase battery cells from Asian technology groups as they are well versed in the mass production of battery cells.
These processes however require a lot of energy and production at locations with high electricity prices such as Germany is therefore unfeasible.
Fraunhofer is nevertheless hoping to change this with its new dry coating technology:
“Our dry transfer coating process aims to noticeably reduce the process costs in electrode coating,” emphasizes IWS project manager Dr. Benjamin Schumm. “Manufacturers can eliminate toxic and expensive solvents and save energy costs during drying.”
“In addition, our technology also facilitates the use of electrode materials that are difficult or even impossible to process wet-chemically.”
Fraunhofer has already set up a pilot plant at Finland’s BroadBit Batteries’ Espoo factory to coat electrodes with dry electrode material instead of wet paste. BroadBit will use it to produce new types of sodium ion batteries.
Current battery electrode coating processes utilize a complex wet-chemical approach.
They first mix the active materials with additives to create a paste. In this process they add organic solvents, which are expensive and usually toxic.
In order to protect operators and the environment, elaborate precautions for occupational safety and reprocessing are necessary.
Once the paste has been applied to thin metal foils, dozens of meter long heating sections dry the coated films before they can be further processed. This drying procedure usually causes high electricity costs.
IWS’ new film transfer technology on the other hand mixes the active material with binding polymers. The scientists then process this dry mixture in a rolling mill known as ‘calender.’
The shear forces in this system tear entire molecular chains out of the binder polymers. These “fibrils” join with the electrode particles as in a spider web, providing the electrode material with stability.
Image and content: Fraunhofer IWS