TAGS: Sustainability / Natural Coatings Powder Coatings
Fraunhofer Institute for Material and Beam Technology IWS has developed DRYtraec® – a new dry-coating process. The technology is environmentally friendly and cost effective and can be used on a large scale, giving it the potential to revolutionize the manufacturing of battery electrodes.
Energy-efficient Ways to Manufacture Batteries
The fast-growing electromobility sector is therefore looking for new ways to reduce the energy required to manufacture batteries and thus to design them to be as cost effective and environmentally friendly as possible. DRYtraec® is a promising solution developed by an interdisciplinary research team at Fraunhofer IWS in Dresden that focuses on the production of the battery electrodes.
A key component of any battery, electrodes normally consist of a metal foil with a thin coating. This coating contains the active components that are responsible for storing energy. “
The conventional coating process uses a wet chemical method that applies what is known as slurry,” explains Dr. Benjamin Schumm, group manager for chemical coating technologies at Fraunhofer IWS.
The active material, conductive carbon and binders are dispersed in a solvent to make a kind of paste, which is initially applied to the metal foil to form a wet coating. “
Extremely large machines with very long drying tracks are needed to ensure that the solvent will evaporate afterward. With DRYtraec®, we can design this process more efficiently.”
Special Binder and Shear Forces from Rotating Rollers
The new coating process essentially uses similar raw materials as in the slurry process. The dry coating technology developed at Fraunhofer IWS works without solvents, but instead uses a special binder. Together, the materials form a dry mixture that is fed into a calender gap — a gap between two rollers rotating in opposite directions. The crucial detail is that one of the rollers must be turning faster than the other.
This induces a shear force, which ensures that the binder forms thread-like networks known as fibrils. “
Imagine it as a spider’s web that mechanically embeds the particles,” says Schumm. The pressure and motion form a fine film on the faster-rotating roller. This film is then transferred in a second calender gap onto a current collector foil.
This allows both sides to be coated simultaneously without significant additional work. In the final step, the resulting coil is cut to the required size and the individual parts are stacked as appropriate in order to produce the finished battery cell.
DRYtraec® therefore has clear ecological and economic advantages over existing battery electrode coating processes.
Removing toxic solvents and long, energy-intensive drying machines from the process benefits the environment.
The new process also accelerates production and requires only one-third of the equipment space of a conventional solution, saving costs in number of ways. In Schumm’s view, the success of the DRYtraec® process comes primarily from the diversity of expertise in the research team at Fraunhofer IWS.
Source: Fraunhofer