A research project is developing laser drying technology as a more climate-friendly and economical method for the volume production of lithium-ion batteries.
The work taking place within IDEEL (Implementation of Laser Drying Processes for Economical & Ecological Lithium-Ion Battery Production) will enable the efficient production of laser-dried anodes and LFP cathodes in a roll-to-roll process for the first time, according to the project partners.
The new process could reduce energy consumption in electrode production by up to 85 per cent, while at the same time doubling the drying speed.
Drying is an established part of electrode manufacturing for high-power battery cells, such as those used in electric vehicles and home storage systems. It is used to dry an electrode paste (slurry), which consists of a specially adjusted, homogeneous active material mixture and is applied to the copper foil of the battery electrode.
Convection dryers have traditionally been used to dry this electrode coating, however the thermal energy transfer is only indirect into the material and thus places a heavy burden on both the CO2 balance and energy costs of battery production.
The IDEEL project, headed up by laser manufacturer Laserline, is therefore looking to up-scale a more energy-efficient drying process in which the coating is irradiated using high-power diode lasers. The process benefits from the strong absorption of infrared laser light in the coating material, allows for more flexible and precise process control compared to common convection technology, and could enable web speeds of up to 30m per minute.
For proof-of-concept, a Laserline high-power diode laser with zoom optics was integrated into an existing film coating system, enabling a homogeneous laser spot to be used for drying the active material. The temperature distribution across the electrode was monitored using a thermographic camera from Optris. Tests were carried out at a web speed of 1.3m/min, with both pure laser drying and hybrid drying – using both a laser and a downstream convection oven – being successfully demonstrated. The hybrid approach can be retrofitted by equipping existing convection oven systems with complementary laser drying technology.
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Initial results indicate that for pure laser drying, the new manufacturing process reduces energy consumption in electrode production by up to 85 per cent. Through the addition of the laser, the hybrid process also yielded a doubling of the drying speed when compared to convection drying only. In addition, the compact design of the new process is expected to significantly reduce the extensive footprint of drying sections in battery production facilities, which are typically more than 100m long.
The research partners next plan to scale up the web speed to 10m/min and then ultimately up to 30m/mi. To this end, Laserline is currently developing optics for generating a large-area laser spot. Initial research results also indicate that a reduction of the system size by a factor of 10 will be possible in the future.
IDEEL project partners
Laserline | Coatema Coating Machinery GmbH | Optris GmbH | Fraunhofer ILT | Fraunhofer FFB | Münster Electrochemical Energy Technology Battery Research Center at the University of Münster | Production Engineering of E-Mobility Components (PEM) at RWTH Aachen University.