Battery enclosure demonstrator testing proves EV feasibility, launches series production projects

Kautex Textron (Bonn, Germany) and Lanxess (Cologne, Germany) have carried out a comprehensive examination using a jointly developed technology demonstrator made from polyamide 6 (PA6) and reinforced with continuous fiber to illustrate the technical plastics’ ability to meet the requirements of electric vehicle (EV) battery enclosures. Lanxess was responsible for the material development and Kautex Textron for the engineering, design and the manufacturing process of the demonstrator.

“The near-series demonstrator passes all mechanical and thermal tests that are relevant for such enclosures. In addition, solutions for the thermal management and leak tightness of the enclosure, for example, have been developed. This has all proven the technical feasibility of these safety components, which are complex and subject to high levels of stress,” Dr. Christopher Hoefs, project manager e-Powertrain at Lanxess, says.

At the moment, an enclosure prototype is being road-tested in a test vehicle to verify its suitability for daily use. “We are currently jointly tackling the first series-production development projects with automotive manufacturers in order to implement the new technology in series production,” Felix Haas, director product development at Kautex Textron, adds.

The demonstrator, which measures around 1,400 millimeters in both length and width, was developed based on the aluminum battery housing of a mid-size EV and designed for mass production. It is manufactured in a single-stage compression molding process with a molding compound based on the PA6 Durethan B24CMH2.0 compound from Lanxess, and does not require any further rework. Crash-relevant areas are reinforced with locally placed blanks made from continuous-fiber-reinforced PA6 Tepex dynalite 102-RGUD600. Compared with an aluminum design, weight savings are around 10%, enhancing range and thus the vehicle’s carbon footprint. The integration of functions, such as fasteners, reinforcing ribs and components for thermal management, reduces the number of individual components compared with the metal design, Lanxess notes, which simplifies assembly and logistical effort and reduces manufacturing costs.

Calculations revealed that the carbon footprint of the large-format plastic enclosure is more than 40% smaller compared to an aluminum design, Hoef reports. Reduced energy use in the production of PA6 compared with metal — in addition to other factors such as the omission of time-consuming cathodic dip painting to prevent corrosion where steel is used — helped to minimize the carbon footprint. The thermoplastic component design also makes recycling the enclosure easier compared with thermoset materials such as sheet molding compounds (SMC), for example.

The tests on the technology demonstrator were carried out in accordance with internationally recognized standards for battery-powered electric vehicles such as ECE R100 from the Economic Commission for Europe or the Chinese standard GB 38031. The all-plastic enclosure demonstrated its performance in all relevant tests. For example, it meets the requirements of the mechanical shock test, which is used to examine the component’s behavior in the event of severe shocks, and the crush test, which the developers use to examine the resistance of the battery enclosure in the event of slow deformation. The results of the drop and vibration tests were also positive, as were those of the bottom impact test. This test examines the stability of the batteries, which are mostly accommodated in the vehicle floor, in the event of ground contact of the vehicle structure, or impacts from sizeable stones.

“All test results corroborate the previous simulations and calculations. A critical failure of the plastic enclosure would not have occurred in any of the load cases,” Haas explains. The demonstrator also proved its resistance to external sources of fire underneath the vehicle in accordance with ECE R100 (external fire).