From e-mobility to communication and medical technology to smart tools or household appliances: the industry needs more and more battery cells. However, their production in gigafactories consumes enormous amounts of energy. Additionally, the large production lines are very inflexible. A possible alternative has now been successfully tested at the wbk Institute for Production Technology at KIT. The approach: process enclosure in mini-environments. In one of the main roles: robots from KUKA.
The future of battery cell production: energy-optimized and flexible
At the wbk Institute for Production Technology of the Karlsruhe Institute of Technology (KIT), pioneering battery production is already tangible. To make it more flexible and efficient, researchers have established an agile cell manufacturing process as part of the AgiloBat project: With the help of robot-based automation in mini-environments, a flexibility has been achieved that was previously only possible in manufacturing. Through customizable processes and program changes, various cell geometries can be produced – without the need for extensive retooling of the system!
For this purpose, researchers developed special robot cells that represent a world first in terms of their design and execution. They were conceived and built by Exentec Germany GmbH, a company of the Exyte Group. Exyte, the international company based in Stuttgart for building technology and plant engineering, designs, plans, and provides sustainable and ultra-pure manufacturing systems for high-tech industries, including semiconductor and battery factories, data centers, or facilities for the biopharma industry.
One of Exentec's focuses is clean and dry rooms. Or to put it in the words of Nicole Neub, Director of the Battery Technology Department at Exentec, "We are responsible for the necessary dry air in the battery manufacturing process."
Every process step in a mini-environment
It is well known that the ambient air in the production of battery cells must contain very little humidity. More precisely: to prevent oxidation or moisture inclusions during the processing of sensitive battery materials, the relative humidity is usually less than 1 percent. Because higher relative humidity can later lead to quality problems or even critical failures of the batteries.
The required dryness is produced in so-called mini-environments. "In this process, individual production steps and the corresponding machines are enclosed, and the filtered air is brought directly to the process," explains Nicole Neub. "This way, only the machine is supplied with clean and dry air – and not an unused large volume in the production hall." In industrial mass production of battery cells, entire production areas are usually operated as dry rooms, which is not necessary for individual processes and consumes large amounts of energy.
In the AgiloBat project, this is achieved through container-like boxes that maintain a dew point of up to -50 °C. "This has nothing to do with the temperature of the production environment," explains the technical director of the AgiloBat project, Sebastian Henschel from the wbk Institute for Production Technology at KIT. Rather, the dew point indicates the temperature to which air must be cooled for moisture to condense. In other words: the lower the dew point, the drier the air. "At a dew point of -50 °C, there are less than 100 water molecules per million air molecules," Henschel emphasizes. "This corresponds to a relative humidity of well below one percent."
Humans are separated from the process – thanks to automation
A crucial factor is the employees: "We humans are made up of 80 percent water, which is anything but helpful in such a process," says Henschel. "And even when we are completely still, we exhale at least 120 grams of pure moisture every hour," adds Nicole Neub. "These are amounts of moisture that significantly negatively affect a stable dew point of, for example, -50 °C." To get the production environment properly dry, people must be kept out of it as much as possible.
That is exactly the approach of Exentec: "In our mini-environment, we consistently separate humans from the process through enclosure," explains Nicole Neub. "This is only possible if the process runs fully automated." And this is where the robots from KUKA come into play.
As part of AgiloBat, four KR CYBERTECH nano, one KR 4 AGILUS, and for cell stacking, two KR SCARA are in use – to the complete satisfaction of the project managers. "Battery cell manufacturers have been using KUKA robots in large numbers in the dry room for years to reduce environmental contamination by employees and to increase production quality," says Thomas Schmidberger, Business Development Manager at KUKA. KUKA has been in contact with battery producers regarding their technological requirements for dry room environments for some time. "We are well aware of the requirements for our products in the dry room from numerous successful customer projects and continuously analyze them together with leading industry experts," emphasizes Schmidberger. As a leading robot manufacturer, KUKA is working on certifying the robots for use in dry rooms.
KUKA robots master the special challenges in the dry room
Because the use in the dry room presents special challenges for the robots. The extremely low humidity can lead to increased wear. This is especially true for materials that contain plasticizers, such as seals or cable connections: with long-term use in the dry room, they can become porous more quickly, and in the worst case, even break. But lubricants can also lose functionality because they lose water components. Special challenges that KUKA takes into account: Since 2020, the automation experts from Augsburg have already gained experience with over 10,000 robots in battery production, more than 1,000 of which are in dry room applications. Customer feedback has been consistently positive.
However, production in mini-environments using automation is not only interesting for battery cell production, but also for many other industries: "In the semiconductor sector, this topic is essential, as well as in the pharmaceutical industry," reports Nicole Neub from Exentec. Here, the advantages of KUKA's wide product range come into play: Due to their versatility and flexibility, the robots can be used in completely different areas, products, and environments.
This has also been proven by the project at KIT: "We wanted to build a maximally flexible system by mapping different process steps through different production modules and then connecting them," says the technical director for AgiloBat, Sebastian Henschel. "In this regard, KUKA's robots have proven themselves absolutely. With their help, we have achieved industrial repeatability and accuracy – combined with a flexibility that we only know from manual production."
Attractive production opportunity, also for small and medium-sized enterprises
These features are particularly attractive for SMEs – it is no coincidence that the team from KIT worked with medium-sized machine and plant manufacturers at AgiloBat. Mini-environments and automation enable them to offer competitive plant technology along the critical process chain within dry room relevant production environments. The insights from AgiloBat allow them to manufacture battery cells flexibly and to test new material systems through industry-related production with small material quantities. "After all, we must not forget that these chemical process steps in battery production involve working with critical substances," says Thomas Schmidberger. "Robot-based automation in conjunction with the use of mini-environments also protects the health of employees."
Above all, however, significant resources can be saved through the production methods applied at AgiloBat – and in two ways: On the one hand, it requires significantly less energy than conventional production. "In gigafactories, between 25 and 40 percent of the total energy demand is solely for creating dry room conditions. And we are constantly drying against the continuous moisture input from every person in the dry room," says Nicole Neub. "Through mini-environments and thus the consistent separation of people and process, this number and thus the ongoing costs, i.e., the OPEX, can be significantly reduced." And secondly, the unusable scrap is significantly reduced: "In large plants, even when they are ramped up, we sometimes have 15 to 20 percent scrap material that has to be thrown away or recycled," calculates Sebastian Henschel from wbk. "We can also significantly reduce this rate through the flexibility of production." KUKA's robots make it possible!
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