Better batteries to give electric vehicles more range: that is the aspiration of the technology development “EMBATT”. It aims to improve volumetric efficiency so that electric vehicles can travel up to 1,000 kilometers with just one battery charge. Since mid-2018, the consortium has been forging ahead to make the new batteries ready for industrial production.

What is special about the EMBATT technology is the way it brings platform and battery together. The battery cells have a bipolar structure: similar to fuel cells, they consist of stacked electrodes connected in series. “A joint electrode array has the active materials for the battery cathode on the one side and the active materials for the anode on the other”, explains Michael Clauß, development engineer at IAV. “The individual lithium ion cells are no longer packed separately in an aluminum housing. In stead, there is just one solid housing for the finished electrode stack”. This eliminates numerous housing components and connection elements, saving costs and space in the vehicle.

The resulting free space can be filled with additional active material so that the battery can save more energy and extend the vehicle’s range. This is exactly the appeal of lithium ion bipolar batteries. Up to now, they have only been made and tested on a smaller scale for use in labs and technical centers (300 x 400 [mm²]).

New production facility in a pilot plant

IAV now wants to change this with its partners Daimler AG, thyssenkrupp System Engineering GmbH and Fraunhofer IKTS (Institute for Ceramic Technologies and Systems). Since mid-2018, they have been working in the “EMBATT goes FAB” project to make the highly promising new technology ready for the next level. After producing the batteries on a small scale hitherto, now the intention is to use larger machines for the individual process steps at the thyssenkrupp pilot plant in Pleißa near Chemnitz. “Two of the new machines are being commissioned; the third one will be set up at the end of 2019”, reports Clauß. “By the start of 2020, we want to reach the point where the coated electrodes can be produced in complete stacks of more than ten.”

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The cells will also be bigger. The previous prototypes measured 30 by 40 centimeters, compared to 30 by 100 centimeters in future. This already brings them much closer to the dimensions of the parts that will eventually go into mass production: they should measure 60 by 100 centimeters, 100 by 100 centimeters or even more. One major challenge is to achieve even cooling of the cells. “We have to keep the temperature within just a few degrees of the optimum range with homogeneous distribution of temperature”, says Clauß. “This is why we are working at dissipating heat throughout the cells and using the heat capacity of the vehicle platform.”

Together with Daimler’s advance engineering team, the IAV experts are also looking at how the battery is connected to the battery management system. They use a virtual vehicle fitted with EMBATT for detailed development of the concept. The prime target that the engineers are working towards consists of achieving 80 percent volumetric efficiency as the basis for a range of up to 1,000 kilometers with one battery charge.

Embatt Logo

With EMBATT, the partners, Fraunhofer IKTS, IAV and thyssenkrupp System Engineering are realizing the implementation of an innovative design principle for large-area, planar bipolar batteries that can be integrated directly into the chassis of an electric vehicle.

In addition to technical issues, IAV is also dealing with the battery’s ecological footprint, as well as the subsequent costs. “Up to now, the samples that we have set up have shown that the technology works”, says Clauß. “Besides battery volume and weight, the costs will play a crucial role in whether it will be successful on the market. We want to show that EMBATT offers both volume and cost advantages.”

Looking for potential partners for a pilot plant

The “EMBATT goes FAB” project will run through to the end of 2020. But Clauß is already thinking about what comes afterwards. “We are looking for potential partners interested in setting up a pilot production line for manufacturing the larger cells which can be integrated in real vehicles for testing the technology under practical conditions.” This would be followed by the start of volume production.

The chances are pretty good, as EMBATT meets the current trends for batteries: bigger cells with more energy per cell. That is precisely the objective of the research project. There is also growing interest in solid state electrolytes, made of ceramic, sulfides or polymers. EMBATT is ideal here, too. “We’re not just optimizing individual components: ours is a radical, disruptive approach”, summarizes Clauß. “Our work is attracting interest from many OEMs and tier-1 suppliers”. And others besides: the manufacturers of solar batteries or rechargeable phone batteries are also interested in the new technology.

The article was published in automotion 02/2019, the automotive engineering magazine of IAV. Here you can order the autmotion free of charge.