At the interface between the powertrain and the structural elements, the battery presents both manufacturers and material suppliers with a complicated task from a conceptual standpoint. The top priority is to provide maximum protection for the core components of e-mobility, but the requirements have many layers. The battery has to be crash-proof and corrosion-resistant, electromagnetically shielded, and cooled.
The developers at thyssenkrupp Steel explored these aspects in depth and developed a virtual prototype that meets all of these requirements. The application engineers from Technology and Innovation in particular were instrumental in developing a lightweight and extremely robust battery housing with a modular structure that enables it to be adapted to a range of vehicle models. “Deformation of the battery must be avoided at all costs in the event of a crash,” says Daniel Nierhoff of thyssenkrupp Steel’s Technology and Innovation department.
The solution is high-tech steel
On the one hand, the housing has to be capable of withstanding a side impact, a bump on the road, or a foreign object striking the battery housing from below without giving an inch. On the other hand, it has to be as light and compact as possible in order to make the most efficient use of the installation space and leave more room for even bigger batteries, which would offer longer vehicle ranges. “These competing requirements are no problem for steel,” says Andreas Untiedt, a customer project engineer at the steel manufacturer.
Untiedt, together with Nierhoff and a hand-picked team of experts, backed up his claim with evidence. “We built our solution on a computer, ran structural calculations, and verified the results with numerous simulations and real tests,” Nierhoff reports. Material properties connected with strength and deformation behavior were inputted into the software to enable the researchers to estimate how different types of steel affect crash behavior.
Together with the carefully considered geometry of the housing, they formed the basis for the crash simulation. “The findings show that our new portfolio of ultra-high-strength dual-phase and manganese-boron steels are the ideal material for our component,” says Nierhoff. The steels also underwent virtual cold- and hot-forming in line with the design requirements to ensure that the components can be manufactured. “And lo and behold, they’re perfectly suited!”
More affordable than other materials
When compared with a battery housing made of aluminum, the 150-kilogram prototype made of steel performs every bit as well, and yet it costs only half as much. Another advantage of the steel battery housing is that liquid cooling can be integrated into its structure. In addition to scoring high on the key points of crash safety, space-saving design, low weight and hence longer battery range, the steel housing is also more cost-efficient than any other raw material.
“And thanks of course to our high-quality coatings, the component will be fully protected from corrosion, even in its highly exposed position on the underside of the vehicle,” says Untiedt. “We have no doubts about our development and see it as an important part of our strategy for making e-mobility affordable. We’re happy to present our design to customers.”