Revolutionizing Battery Production for Electromobility

The future of transportation heavily relies on the development of reliable and durable batteries. As the shift toward electromobility accelerates, the demand for high-performance batteries has spurred intensive research and development. Key areas of focus include thermal management, range, charging time, safety and cost-effective production. One critical aspect that significantly impacts these factors is electrical insulation.

Traditional battery cells, especially prismatic ones, are protected by a film. This method, however, is costly, time-consuming and prone to errors such as condensation under the film and bonding inconsistencies. These issues can lead to expensive rejects and extensive localization efforts. To address these challenges, Venjakob Maschinenbau GmbH & Co. KG (Rheda- Wiedenbrueck, Germany) and Plasmatreat GmbH (Steinhagen, Germany) have collaborated on an innovative solution.

A new approach

Venjakob, a specialist in coating lines, and Plasmatreat, a manufacturer of atmospheric plasma technology, have developed a contact-free protective coating process for battery cells. Instead of using film wrapping, battery cells are coated with a protective layer applied in a continuous process. This method ensures comprehensive protection.

“The protective coating is applied without contact, offering all-around protection and particularly gentle handling during the process,” says Gert große Deters, executive vice president of General Industry & Automotive at Venjakob.

The project, initiated by a premium vehicle manufacturer, sought a reliable alternative to film wrapping. Plasmatreat's Openair-Plasma technology was used for the pretreatment of the battery cells prior to subsequent coating at Venjakob. Using Openair-Plasma, surfaces are ultrafine cleaned to enable reliable, long-term stable coating application.

Meanwhile, Venjakob has developed a modern system that makes it possible to coat battery cells in various formats with 100% UV coating material in a contact-free process. 

Initial tests confirmed the effectiveness of the combination of Openair-Plasma and subsequent lacquer coating, achieving adhesion values of over 15 MPa in tensile shear tests.

“This means that the batteries can be bonded in the overall structural system of the vehicle in the battery module design,” says Lukas Buske, managing director at Plasmatreat and head of plasma applications.

Precision cleaning with plasma

Plamatreat’s Openair-Plasma technology is a key enabler in this process and ensures optimum adhesion of the protective coating. It is based on a simple physical principle: the supply of energy causes aggregate states to change. If a gas, for example compressed air, is supplied with additional energy, it is ionized and enters the high-energy plasma state as the fourth state of matter. When plasma with its high energy level comes into contact with materials, the surface properties change, for example from hydrophobic to hydrophilic.

Plasmatreat has made this process usable on an industrial scale and adapted it to the customer’s production process with the corresponding parameters for ultrafine cleaning of the batteries before the coating process. The Openair-Plasma is applied precisely to the metal surface of the battery cells in a plasma treatment unit (PTU) under atmospheric pressure using simple compressed air and electricity through specially developed nozzles.

Compared to conventional cleaning methods, the process is more environmentally friendly, selective and inline capable. The surfaces of the battery cells are reliably cleaned of wafer-thin layers of dust and residual traces from the production process, such as oil or grease, so the protective coating can be applied without gaps and long-term adhesion is achieved.

Automated, contact-free coating

Following the precision cleaning, Venjakob's system coats the prismatic battery cells with a special 100% UV protective coating in a fully automated, contact-free process. This method minimizes the risk of damage to the sensitive battery cells and enables increased production speed.

It is essential to protect the so-called terminals from overspray during the coating process. Venjakob developed a special workpiece carrier for the desired six-sided coating in a single pass, which reliably protects the sensitive areas and electrical poles of the battery cell from overspray during the entire coating process.

In the spray booth, the cells are coated by permanently installed spray guns. As no gripping, turning or other handling is required, the risk of damage to the sensitive battery cells is minimized.

The contact-free process also enables increased production speed. To keep paint consumption as low as possible, any excess coating material that collects on the belt is removed and fed back into the process. After automatically passing through an UV channel and repeating these two steps in the continuous process, the coated cells are discharged. Thanks to immediate curing, they can be processed directly. This speeds up the entire battery manufacturing process.

Versatility and efficiency

The system processes prismatic battery cells in different formats without having to changeover, thereby minimizing sources of error in battery cell production. The overall result is an effective and efficient alternative to expensive and time-consuming film wrapping.

The plasma technology also enhances structural bonding processes, making it adaptable to various industries and materials, including plastic components.

This innovative approach to battery cell production represents a significant advancement in the electromobility sector, offering a robust, efficient and scalable solution for future transportation needs.

“We believe that the existing solution for ultrafine cleaning and coating battery cells has great potential. This is because the increased strength of the coating, in contrast to foiling, results in a further advantage for the battery module manufacturer: the battery cells can be bonded directly to the housing base while complying with all safety requirements,” Buske says. “Upstream cleaning with plasma technology can help to further improve the structural bonding process.

Buske says the Venjakob and Plasmatreat systems are designed to be integrated into customers’ current processes. The plasma systems can be easily integrated into existing production lines. This means that this solution for ultrafine cleaning and coating with UV lacquer can also be transferred to other industries.

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For more info visit venjakob.com or nutroinc.com.