High-performance battery cells are a crucial prerequisite for the successful electrification of the mobile sector. Now researchers at the Fraunhofer Institute for Laser Technology ILT in Aachen have developed innovative laser-based technologies for the production of lithium-ion batteries. The solution presented at HANNOVER MESSE 2023 offers significantly shorter charging times and a longer service life than lithium-ion batteries manufactured in the conventional way. In addition, laser-based drying is expected to make water-based electrode coating in production significantly more energy-efficient.

Drying by diode laser

Up to now, electrodes for lithium-ion batteries have usually been produced by coating a copper foil with graphite paste and then drying it in a continuous oven at 160 to 180 degrees Celsius. The 60 to 100 metre long ovens not only take up a lot of space in production, they also require a lot of energy. The Fraunhofer experts have now developed a system in which a diode laser takes over the drying. The laser beam is extended by special optics that expose the electrode over a large area. The jet-black graphite absorbs the energy of the laser beam. Due to the onset of interaction, the graphite particles heat up and the liquid evaporates. Compared to continuous furnaces, the diode laser requires up to 50 percent less energy; at the same time, the system hardly emits any heat to the outside and requires significantly less space.

Small channels ensure better ion flow

The team at the Fraunhofer ILT has also succeeded in improving the power density and service life of lithium-ion batteries. A high-power ultrashort pulse laser (UKP) with 1 millijoule pulse energy introduces a hole structure - the so-called channels - into the battery electrode. These channels reduce the path length of the ions and thus ensure a faster charging process. As a result, the number of possible charging cycles and ultimately the service life of the battery also increases.

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