Researchers developed a new battery electrodes manufacturing process that eliminates the need for toxic raw materials and allows for faster production.
Battery manufacturing processes involve toxic solvents and require a lot of space and energy. The key components for any battery are electrodes consisting of a metal foil with a thin coating. The coating contains active components that are responsible for storing energy. The coating processes use a wet chemical method that applies what is known as slurry. To form wet coating, the active material, conductive carbon and binders are dispersed in a solvent to make a kind of paste. Large machines with very long drying tracks are needed to ensure that the solvent will evaporate afterward.
The manufacturing system developed by the Fraunhofer Institute for Material and Beam Technology IWS called DRYtraec is a new dry-coating process to make the manufacturing more efficient. According to the researchers, the developed technology is environmentally friendly, cost effective and can be used on a large scale, giving it the potential to revolutionize the manufacturing of battery electrodes.
The new coating process uses similar raw materials as in the slurry process, but it works with a special binder instead of solvents. Together, the materials form a dry mixture that is fed into a gap between two rollers rotating in opposite directions. The rollers must turn faster in order to induce a shear force, which ensures that the binder forms thread-like networks known as fibrils.
A fine film is made by fast rotating rollers, which is transferred to another such gap onto a collector foil to allow both sides to be coated simultaneously. The resulting coil is then cut to the required size and the individual parts are stacked as appropriate in order to produce the finished battery cell.
The new process eliminates the need for toxic solvents and long, energy-intensive drying machines from the process. It also accelerates production and requires only one-third of the equipment space of a conventional solution, saving costs in a number of ways. Thus, it has clear ecological and economic advantages over existing battery electrode coating processes.
“The range of possible uses for the technology is not limited to a particular cell chemistry,” Dr. Benjamin Schumm, Group Manager for Chemical Coating Technologies at Fraunhofer IWS, says about the applicability of this process. “It could equally be used on lithium-ion cells as on lithium-sulfur or sodium-ion cells. We are even looking at solid-state batteries. These will be increasingly important in the future, but the materials cannot tolerate wet chemical processing. Thus, DRYtraec allows us to offer a very promising solution to this problem.”