selectrify^® – steel solutions for electric mobility

With cost-efficient lightweighting solutions for the vehicle structure, robust and safe battery housings and electrical steel for efficient electric motors, thyssenkrupp Steel is demonstrating the enormous potential of innovative steel solutions for electric vehicles. The way we build cars is changing. The electric car 2.0 doesn’t simply replace a conventional engine with a battery and electric motor. It calls for a design that meets new requirements and at the same time offers new possibilities.

Electric car 2.0: almost everything changes

Engineers, designers, technicians and material suppliers are having to rethink. The packaging, body construction and chassis of battery-electric vehicles are fundamentally different from conventional designs. The elimination of internal combustion engine, transmission, tank and exhaust system allows greater design freedom and requires changes, for example, to the energy-absorbing zones in the front end. At the same time, the high weight of the battery generates additional loads in all crash load cases.

Cost-efficient lightweighting solutions are needed to drive forward the mobility revolution. Robust and safe battery housings must ensure that electric cars at least match the safety standards of conventional vehicles. And with more efficient electric motors, the stored energy must be converted into greater range

Steel: “The Material of Mobility”

thyssenkrupp Steel has a high level of expertise in all aspects of electric mobility. Steel is crucial to the mobility revolution. It’s indispensable in generators and electric motors. And it’s the number one choice for body construction, battery housings and chassis solutions.

“selectrify^®” is the name under which thyssenkrupp Steel has combined its e-mobility activities and a synonym for the enormous potential of innovative steel solutions for electric vehicles.

Mr. Matusczyk, is it possible to build cars without using any steel at all?

No, impossible. Steel was, is and will always remain the ‘material of mobility’ and as such the core material in the automotive industry – even in the era of electromobility. That’s because steel combines great potential for lightweight design with excellent cost effectiveness. Let me back this up with a few figures: The structure of a present-day electric car, such as VW’s ID.4, weighs around 440 kilograms including the battery enclosure. The doors, hood and tailgate weigh another 120 kilos or so. Since aluminum offers no or only a minimal weight advantage in respect of the vehicle’s body structure, steel is generally the material of choice. In many cases, this also applies to the add-on parts, i.e., doors, hood, and tailgate. In addition, all EV drive motors require a large amount of electrical steel. Depending on the model and whether it’s a battery electric (BEV) or a plug-in hybrid vehicle (PHEV), between 20 and 90 kilos of electrical steel go into in each motor. There is no alternative to electrical steel for this specific purpose.

But when it comes to the battery housing in electric cars – which is so important from the point of view of safety – manufacturers don’t yet appear to be 100 percent convinced that steel is the right material for the job, do they?

There are, so to speak, historical reasons for this. The first electric vehicles built were actually standard conventional vehicles into which a heavy battery housing was retrofitted. It’s due to this approach and the need to keep the extra weight as low as possible that aluminum is still the go-to material for the battery housing, at least in Europe. That’s a pity, because our research has shown that steel is only minimally heavier and clearly a much cheaper and more sustainable alternative. I’m sure we’ll see more and more vehicles with battery housings made of steel or at least a blend of materials in upcoming generations. Because now it’s all about properly integrating the function of the battery housing into the vehicle body. This means designing the battery housing as part of the side-impact protection structure from the word go.

One aspect of electric cars hotly discussed is that of fire safety. How do you rate steel in this context?

High-performance batteries in cars demand extremely high standards in terms of safety. The individual battery cells must be protected against collision damage at all costs. Today’s ultramodern steels offer unbelievably high degrees of strength and can take on an important protective role for the battery in locations such as the side sills, the B-pillars and in other crash-relevant positions. However, if a car does actually catch fire, steel has a real trump up its sleeve: Steel only melts at temperatures above 1,425°C. Aluminum alloys on the other hand liquefy at temperatures as low as 500°C. An appropriately dimensioned steel cover for the battery is therefore capable of withstanding those decisive few minutes longer to give the rescue services the time they need to get people out and save their lives.

A general question: What makes steel so special for the construction of both electric and conventional vehicles?

Steel is available the whole world over and the manufacturing processes are not only safe, but have been tried and tested over decades. What’s more, steel can be recycled without impacting its quality and cars made of steel can be easily repaired anywhere in the world – unlike car bodies made of fiber-reinforced plastics, for example. But most importantly, today’s steels are extremely strong and offer great potential for lightweight design at an unrivalled cost/performance ratio. We call this “cost-effective lightweight design” – and steel is the absolute world-leader in this respect.

Which means lightweight design, safety, fire protection and cost-effectiveness can all be combined well with steel?

Yes, and more than that. Electric cars are not an end in themselves – we want to prevent emissions and protect the environment. While they have no tailpipe or pump out toxic exhausts, their production, of course, still results in environment-polluting emissions. So it’s important to take the environmental impact of production also into account when selecting materials. And this is where new steel concepts for battery housings come off very well. Compared to the aluminum-based solutions deployed today, they produce up to 50 percent less climate-killing CO₂, at significantly lower cost, with only a slight increase in weight.

That sounds good, but you still face a number of challenges in development moving forward. What will be the main focal points in the next few years?

Even though we already have a wide range of highly suitable products, it’s still possible we’ll develop more new lightweight steels that will meet the needs of electromobility even better. This is what we’re working on together with our customers. With electrical steel, too, there’s still scope for further development and optimization. But the key thing is if we really want to realize clean mobility, at some point steel production will also have to be carbon-neutral. We have developed our own in-house technology to achieve this and have set ourselves very ambitious goals. By as early as 2030, we want to be able to supply the marketplace with a large share of carbon-optimized products and reduce our CO₂ emissions by 30 percent. And we want to be carbon-free by 2050. This is not something that can be done just like that – the technology is extremely expensive and we’re Germany and Europe and not an island. We can only survive long term in the global market if the same rules apply to all steel producers. And this level playing field can only be brought about by politicians. At the same time, it must be clear to everyone that environmental protection and zero emissions do not come free of charge. However, we are certain that there is a greater willingness to pay for vehicles that are completely carbon-free in respect of both production and use.

Mr. Matusczyk, many thanks for this interview!