Researchers in Austria have designed a new type of electric car battery enclosure that combines...
Researchers in Austria have designed a new type of electric car battery enclosure that combines wood and steel, providing a safer and more sustainable alternative to the aluminum cases currently used by Tesla.
The team of experts led by Florian Feist, PhD, from the Institute of Vehicle Safety at the Graz University of Technology (TU Graz) engineered the hybrid battery case as part of the Bio!Lib project.
Made from thin sheet steel filled with wood, the new structure greatly reduces the environmental footprint of battery production. Conventional aluminum cases with chambered designs consume far more energy to produce.
The project was reportedly inspired by both ecological concerns and the aim to enhance crash performance. Battery enclosures are crucial for the safe operation of electric vehicles, protecting the battery cells from deformation or fire in the event of a crash.
A prototype that rivals Tesla’s Model S battery case
For the study, the team replaced aluminum with a thin steel shell filled with wood. “The steel skin is welded directly in the presence of the wooden core,” Feist said, adding that the structure of wood is made up of tiny cells that collapse under pressure.
They can therefore absorb a lot of energy in the event of a crash. In addition, the underbody and lid are made from the same steel-wood composite, while the battery interior is reinforced by rib-like cross struts. The team was amazed by how well the case performed in simulated crash tests.
In the critical pole crash test, where vehicles collide with a steel pillar at high speed, he Bio!Lib enclosure showed intrusion values nearly identical to Tesla’s aluminum battery case in the Model S.
Meanwhile, to enhance fire and heat resistance, the researchers turned to cork, a renewable raw material, as an insulating fire protection layer. “When cork is exposed to very high temperatures, it chars,” Feist stated.
“Carbonization leads to a sharp drop in the already relatively low thermal conductivity, which protects the structures behind it,” the scientist said, emphasizing that this also applies to the interior of the vehicle.
Superior fire protection
The team was in for a real surprise when they carried out a so-called pyrotechnic test, which simulates a battery fire. The cork-insulated enclosure withstood battery fire conditions exceeding more than 2,372 degrees Fahrenheit (1,300 degrees Celsius).
During the same simulations, the Bio!Lib case maintained structural integrity and kept the temperature on the opposite side of the fire about 212 degrees Fahrenheit (100 degrees Celsius) cooler than Tesla’s aluminum enclosure.
After completing the tests, the team joined forces with the Wegener Center for Climate and Global Change at the same university to assess the sustainability of their metal-wood hybrid design.
Their analysis found that the Bio!Lib case had a lower environmental impact than aluminum-based versions across nearly all categories, including energy use, water consumption, and pollution.
“In all areas, the Bio!Lib housing performs better than the market standard made of aluminum; only in the impact category ‘land use’ was it the other way around,” Feist concluded in a press release.
The team now aims improve cork reusability and component recyclability, in addition to finding out whether low-value wood, such as thinning or secondary-use material, can be utilized for the enclosure.