Battery technology for electric cars is still in its infancy, according to Professor Andreas Hintennach, who works at Mercedes-Benz. Not only is there still a lot of stretch in the current technology, the battery technology of the future also offers many possibilities. A brief overview.

The current situation is clear: lithium-ion batteries are the standard for use in electronic devices and electric vehicles. These can eventually be repaid by battery packs with so-called solid-state battery cells. There are also conceivable evolutions of the lithium-ion batteries.

"In the coming years, lithium-ion will be leading. Obviously, a lot of work is being done on innovation and the alternatives to the 'post-lithium-ion time'. The focus is not least on greater energy density and fast charging. We learn a lot about alternative materials and cell chemistry, "said Hintennach.

In addition to a long life of the battery, reuse is highly rated. That is also of great political importance, because we hardly have any primary sources here in Europe. Returning materials to production is crucial, according to Hintennach.

"I think that within eight to ten years we will have enough used vehicle batteries available to recycle cobalt, nickel, copper and later also silicon on an industrial scale. We are already doing that with our own test battery cells. We are going to 99 percent reuse and there efforts are also being made to reclaim lithium from the cells. "

We are working hard on alternatives to lithium-ion batteries. (Photo: Daimer)

Solid state battery safer

The other revolution in battery technology that has been hanging over the market for many years is the solid-state battery. A lot is expected of that, but according to Hintennach the euphoria is only partly justified.

"It is above all a safer and simpler solution. Why safer? Because, unlike today's liquid electrolyte, it is not flammable," says Hintennach. In fact, the technology is already available. Toyota would already use vehicles with a solid-state battery during the Tokyo Olympics this summer, and at Mercedes the Citaro bus will get this technology later this year.

There is still a long way to go for the next step with applications in passenger cars. After all, they are used very differently from the predictable pattern of a bus, Hintennach warns. "In large buses and certainly articulated buses, there is the additional advantage that you have a lot of space available. Another plus: their lifespan is very good if you use them like this. However, very fast loading is a problem and that is a stumbling block in passenger car applications. . "

Sulfur very good for durability

You could summarize the other major developments that are emerging as work on both 'poles'. Call it an evolution of the existing lithium-ion technique. This happens on the anode and cathode sides, between which the lithium ions 'move' during charging and discharging. When you drive, the Li + ions go from the anode side to the cathode side. The reverse happens at the charger.

"An important research project is the replacement of graphite in the anode side of the cells with silicon. You will see that happen in the coming years and this is a significant step, because it allows us to improve the energy density by 20 to 25 percent. It also makes very fast loading possible ", says Hintennach.

Silicon then also opens doors that now remain closed, the research top man adds. A number of promising 'building materials' cannot be combined with the graphite currently used.

For example, manganese has full attention, a material that has been used in non-rechargeable batteries for many years. A little later, lithium sulfur is a possible alternative, but a breakthrough is not expected there within ten years. The latter variant is nevertheless noted with great precision, because sulfur is widely available and even almost a residual product.

Hintennach: "If you can replace nickel and cobalt in today's battery cells with sulfur, you will improve the durability enormously. It also has great potential in energy density, so you can drive up to 1,000 kilometers. In practice, you are talking about smaller battery packs that you can charge better. The Achilles heel is for the time being that the lifespan is too short. "

The whole story was in AutoWeek 26