They cross thundering forest streams and board narrow coastal roads, they master deserts and climb rocky mountain landscapes: More and more car manufacturers are advertising their fully electric new developments with such and similar images. Instead of presenting the electric cars only in an urban environment, it is more and more common to go out into the country, into the wild and untamed nature.
The message behind it: electric mobility can also master longer distances and is above all fun! Environmental friendliness is no longer the main selling point for electric vehicles (EVs)—instead they advertise their efficiency, greater range, state-of-the-art software and pure driving pleasure. Along with the challengers such as Tesla, Byton, Lucid Motors, Canoo and Rivian, the established manufacturers are also investing in the expansion and development of their electric models.
Composite materials with carbon and glass fibers really show off their advantages in EVs. Their lighter weight increases the vehicle’s range and efficiency. At the same time, the materials’ stiffness makes the inside of the car even safer. Additional benefits include their low thermal conductivity and exceptional fire resistance. The latter properties make the materials especially useful in the battery enclosures for electric vehicles.
Batteries significantly increase the weight of electric vehicles
Why is this? Because the battery unit has one of the greatest weight-saving potentials for the vehicle. Since the battery is one of the central components in EVs, it plays a decisive role in the final weight of the vehicle. Composite materials help reduce the overall weight; their additional benefits are an extra plus. “Traditional battery enclosures for electric vehicles are mainly made of aluminum and steel,” says Jürgen Joos, Head of Program Management Materials Automotive at SGL Carbon. “Compared to these, battery enclosures made of composites are around forty percent lighter.”
Customized battery enclosures for electric vehicles
A battery enclosure made of fiber reinforced plastics (called composites) can save a lot of weight. Composites also have further advantages, providing optimized crash performance, improved underbody and fire protection, and a more constant temperature within the battery.
Aside from all this, carbon and glass fiber-based materials offer great safety advantages. “They increase the stiffness and corrosion resistance, fulfill the requirements for the battery enclosure’s water and gas impermeability, and improve the fire and underbody protection,” Joos says. In addition, the battery is also better shielded against cold and heat such that additional insulation can be dispensed entirely if the battery is designed accordingly.
Since underbody and lid of the battery enclosure are made of flat components, these can be produced in large quantities relatively easily and with the efficient use of materials. Thanks to new manufacturing processes, also the frame structure can be made of composites. “Overall, battery enclosures made of composites can thus even achieve similar cost levels to aluminum and steel in the future,” Joos says.
Only lightweight construction offers the opportunity to break the spiral of increasing weight and its disadvantages for electric vehicles. It is therefore of even greater importance for electric vehicles than for conventional cars.
Dr. Ulrich W. Schiefer, CEO of the mobility developer AtTrack
CEO Ulrich Schiefer of the mobility developer AtTrack knows how important every gram of weight savings is, particularly for e-mobility. As he explains, every kilogram of weight saved has positive effects on energy use, wear-and-tear, range and acceleration for EVs. Furthermore, less weight in combination with the same range means that smaller and lighter batteries can be installed. This saves costs, reduces the space required for installation and shortens charging times. Researchers at the Munich University of Applied Sciences have calculated that 100 kilograms less weight can reduce overall battery costs by up to five percent.
Innovations in automotive construction
Composites and graphite-based solutions play a central role in developing modern vehicles. They support more sustainable vehicle concepts by helping to improve vehicles’ efficiency, driving behavior and safety. The portfolio of solutions runs the gamut from structural components, battery enclosures and suspension systems, to pump components and seals, to anode systems for batteries and materials for fuel cells.
“The spiral of increasing weight is moving much faster for EVs than for combustion engine models,” says Schiefer. After all, the additional power required can only be generated by an engine with higher performance and by installing more battery cells. But this increases the weight, which then also requires stronger and thus heavier brakes, chassis and tires. So the spiral continues to turn. Schiefer believes that the only real opportunity to break out of this cycle is lightweight construction. “It is therefore of even greater importance for electric vehicles than for conventional cars.”
An Industry in Upheaval
The far-reaching changes in the automotive industry towards electromobility aren’t being stopped by the corona pandemic. Quite the contrary: in many countries, “green” economic stimulus packages are already being considered and passed. In Germany and France, for instance, the governments have just significantly increased subsidies for the purchase of electric vehicles as a result of the crisis.
At the same time, the electrification of the automotive sector is also changing the vehicles’ design. With combustion engines unnecessary, the large-volume and heavy battery is moving into focus. Its placement in the center of the vehicle has enabled another trend in automobile construction: the even more consistent use of platform architectures upon which various vehicle models can be placed. For instance, instead of having to construct two different vehicle frames for an SUV and a van, both vehicles could be built on the same platform, saving both money and time.
Advanced manufacturing processes and new materials assist in the continuing optimization of such designs. This brings lightweight construction with composite materials into play because composites not only make it possible to build lighter and safer vehicles, but also enable particularly flexible designs.
The upturn in electromobility thus means great growth potential for these lightweight composite materials. Joos at SGL Carbon is certain of this: “These new vehicle architectures will all continue using components made of fiber materials. Moreover, the battery and its enclosure mean that an important component is now being added that especially benefits from lightweight construction.”
SGL Carbon is already prepared for the increasing demand. From precursor materials to carbon fibers and carbon fabrics to finished vehicle components, all the materials relevant to lightweight construction in the automotive sector are being produced. Joos predicts: “We’re benefiting from the increasing demand for composites along the entire value chain.”