Lithium batteries are found in e-cars, electric scooters and many other modern means of transportation. Their production is booming and with it the manufacture of the necessary electrodes. For this purpose, metal foils, mostly made of copper, are coated with a paste called slurry.
Drying the paste on the metal foils is not trivial, but with the help of infrared emitters it can be accelerated considerably, as tests in our application center show.
Up to now, electrode slurry has usually been dried by hot air but infrared heat technology is now becoming increasingly established. Infrared heat radiation has a significantly higher heat transfer capacity than air and therefore he drying step can be greatly accelerated.
A series of intensive tests at Heraeus Noblelight, the specialist for infrared applications, has now shown that the wavelength and power of the infrared emitters combined with the optimum drying time have a major influence on the drying result.
Binder crosslinking and residual moisture content can be strongly influenced by these parameters, so it is worth taking a close look at the design of the infrared drying system. This is confirmed by field tests at customers. Retrofitting infrared emitters to existing hot-air drying systems significantly accelerates the production speed, almost doubling it.
Practical test series and computer simulation optimize the system
In order to identify the interaction of the various parameters and understand their influences, Heraeus conducts drying trials with different radiation sources and outputs at its application center. In addition, the process from coating to drying to analysis can be simulated here on a laboratory scale.
A film applicator precisely coats the substrate films with electrode paste in different layer thicknesses. After infrared drying, residual moisture is determined and adhesion tests are carried out. In this way, the relationships between film thickness, drying speed and adhesion can be readily identified. Infrared emitters are individually adapted to the required parameters in the wavelength range and also in the power density.
Heraeus Noblelight also carries out process optimization using numerical simulation (Computer Aided Engineering – CAE). Production systems can be analyzed and optimized using virtual product data models. This involves simulating precise information on temperature distribution in the coated foils, feedback from environmental influences and air flow for the removal of moisture/water vapor.
Heraeus Noblelight specializes in the manufacture and application of high-quality light sources covering the electromagnetic spectrum from ultraviolet to infrared. The company has more than 40 years of experience in infrared technology and offers the know-how, products and systems to provide efficient and effective solutions throughout the industry.