Battery cell production in mini-environments: flexible automation in the dry room

From e-mobility to communication and from medical technology to smart tools and household appliances, industry needs more and more battery cells. However, their production in gigafactories consumes enormous amounts of energy. In addition, the large production lines are very inflexible. A possible alternative has now been successfully trialed at the wbk Institute of Production Engineering at KIT. The approach: process containment in mini-environments. Robots from KUKA fill one of the main roles.

The future of battery cell production: energy-efficient clean and dry rooms

At the wbk Institute of Production Engineering at the Karlsruhe Institute of Technology (KIT), pioneering battery production can already be experienced. To make this more flexible and efficient, researchers have set up an agile cell production facility for lithium-ion batteries as part of the AgiloBat project. With the help of robot-based automation in mini-enivronments, a level of flexibility was achieved that was previously only possible in the manual production of lithium-ion batteries.

The KR 4 AGILUS in action in one of the robot cells at KIT.

Thanks to customizable processes and program changes, a wide variety of cell geometries can be produced in the drying room without having to extensively retool the system. The researchers developed special robot cells for this purpose, which are a world first in terms of their design and construction. They were designed and built by Exentec Germany GmbH, a company of the Exyte Group. Exyte, the international building technology and plant engineering company based in Stuttgart, designs, plans and provides sustainable and ultra-clean production facilities for high-tech industries, including semiconductor and battery factories, data centers and facilities for the biopharmaceutical industry. One of Exentec's specialities is clean and dry rooms. Or, in the words of Nicole Neub, Director of Battery Technology 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. To be more precise: to prevent oxidation or moisture inclusions during the processing of the sensitive battery materials, the relative humidity is usually less than 1 percent. If it is higher, this can later lead to quality problems or even critical battery failures.

The relative humidity in the robot cells is usually less than 1 percent.

The required dryness is produced in so-called mini-environments. “Individual process steps in production and the associated machines are enclosed and the filtered air is brought directly to the process,” explains Nicole Neub. “This means that only the machine is supplied with clean, dry air and not a large, unused volume of air from the production hall.” In the industrial mass production of battery cells, entire production areas are usually operated as a drying room, which is not necessary for individual processes and requires large amounts of energy.

Extremely dry air: process enclosure makes it possible

In the AgiloBat project, energy reduction is achieved using container-like boxes in which a dew point of up to -50 °C prevails. “This has nothing to do with the temperature of the production environment,” explains the technical manager of the AgilotBat project, Sebastian Henschel, from the wbk Institute of Production Engineering at KIT. Rather, the dew point indicates the temperature to which the 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 by volume,” explains Henschel. “That corresponds to a relative humidity of far less than one percent.”

With the help of KUKA robots, we have achieved industrial precision with a flexibility that we are otherwise only familiar with from manual production.

Sebastian Henschel, technical director of AgiloBat at KIT

People are separated from the process thanks to innovative automation

A decisive factor here is the employees: “We humans are made up of 80 percent water, which is anything but helpful in a process like this,” says Henschel. “And even when we are at absolute rest, we exhale at least 120 grams of pure moisture every hour,” adds Nicole Neub. “These are quantities of moisture that have a significant negative impact on a stable dew point of -50°C, for example.” In order to get the production environment really dry, people need to be kept out of it as much as possible. This is precisely Exentec's approach: “In our mini-environment, we consistently separate people from the process by enclosing them,” explains Nicole Neub. “Of course, this is only possible if the process is fully automated.” And this is where the robots from KUKA come into play.

The two KR SCARA and the KR CYBERTECH nano work together in the mini-environment with extreme efficiency and precision.

Numerous successful customer projects speak in favor of KUKA

Four KR CYBERTECH nano, one KR 4 AGILUS and, for cell stacking, two KR SCARA robots are in use as part of AgiloBat 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 in order to reduce environmental contamination by employees and increase production quality,” says Thomas Schmidberger, Business Development Manager at KUKA. KUKA has been in dialogue with battery manufacturers for some time regarding their technological requirements for dry room environments. “We are very familiar with the requirements for our products in the dry room from numerous successful customer projects and are continuously analyzing them together with leading industry experts,” emphasizes Schmidberger. As a leading robot manufacturer, KUKA is working on certifying its robots for use in dry rooms.

The robotic cells developed by the KIT researchers are a world first.

KUKA robots master the special challenges in dry rooms

This is because dry rooms pose special challenges for robots. For example, the extremely low humidity can lead to increased wear. This applies in particular to materials that contain plasticisers, such as seals or cable connections. Long-term use in dry rooms can cause them to become porous more quickly and, in the worst case, even break.

The robots from KUKA master the special challenges in the drying room.

But lubricating greases, for example, can also lose their functionality because they lose water components. These are special challenges, which KUKA takes into account. Since 2020, the automation experts from Augsburg have already gained experience with over 10,000 robots in battery cell production, including more than 1,000 in dry room applications. Customer feedback has been consistently positive.

Battery cell manufacturers have been using KUKA robots in the drying room for years to reduce environmental contamination and increase production quality.

Thomas Schmidberger, Business Development Manager at KUKA

Repeatability and accuracy meet flexibility

However, production in mini-environments using automation is not only interesting for battery cell production, but also for many other industries. “The topic is essential in the semiconductor sector, as well as in the pharmaceutical industry,” reports Nicole Neub from Exentec. This is where the advantages of KUKA's broad product range come into their own: thanks to their versatility and flexibility, the robots can be used for completely different areas, products and environments.

The KR CYBERTECH nano can be flexibly integrated into the system.

This was also demonstrated by the project at KIT: “We wanted to build a system with maximum flexibility by mapping different process steps using different production modules and then linking them together,” explains Sebastian Henschel, Technical Manager for AgiloBat. “The robots from KUKA have really proved their worth here. With their help, we have achieved industrial repeatability and accuracy – combined with a flexibility that we are otherwise only familiar with from manual production.”

Attractive production option for small and medium-sized enterprises

These features are particularly attractive for SMEs. It is no coincidence that the KIT team at AgiloBat worked together with medium-sized machine and plant manufacturers. Mini-environments and automation enable them to offer competitive plant technology along the critical process chain within dry-room-relevant production environments. The findings from AgiloBat enable them to manufacture battery cells flexibly and to test new material systems through industry-oriented production with small quantities of material. “Finally, 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 therefore also protects the health of employees.”

Like all KUKA components, the KR CYBERTECH nano also met the requirements of the AgiloBat project to the complete satisfaction of the researchers.

Mini-environments and the consequent separation of people and processes can significantly reduce running costs.

Nicole Neub, Director of Battery Technology at Exentec

Significant savings in running costs and resources

Above all, however, the production processes used at AgiloBat can save considerable resources in two respects. Firstly, significantly less energy is required than in conventional production. “In the gigafactories, between 25 and 40 percent of the total energy requirement is used just to create dry room conditions. And we are constantly drying against the continuous moisture input of every person in the dry room,” says Nicole Neub. “Mini-environments and the consistent separation of people and processes can significantly reduce this figure and therefore also the running costs, i.e. the OPEX.” Secondly, the amount of unusable scrap is significantly reduced: “With the large systems, even when they are run in, 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 by making production more flexible.” The robots from KUKA make it possible!