No more Toxic Solvents

Until now, it has been common practice to coat the metal foils for battery electrodes with a wet paste consisting of active material, conductive carbon blacks, binders and solvents. Huge machines subsequently dry the film and evaporate the solvent. However, such “slurry“ processes require high energy input.

A new Path for more Sustainability

Fraunhofer IWS now offers an excellent alternative with its DRYtraec^® technology. This dry electrode coating process eliminates the use of toxic solvents but uses a special binder instead. The mixed powder is fed into a calender gap between two rollers rotating in opposite directions – whereby one of them rotates faster than the other. The resulting shear forces cause the binder to form so-called fibrils. Like a spider‘s web, they mechanically embed the particles. A second calender gap transfers the fine film to a current collector foil. Finally, a machine cuts the films to precise shape for use in the battery cell.

This technology eliminates solvents, which are hazardous to the environment and human health. DRYtraec^® can also significantly reduce the energy and space consumption of battery factories. First prototype systems are already in operation. Fraunhofer IWS is currently working with several industrial companies on further development steps aiming at transferring the technology to industrial series production.