Batteries: Charged with potential

    Battery technology can boast one success after another. Ranges are getting longer, charging times shorter, and the price more affordable.

    Battery technology can boast one success after another. Ranges are getting longer, charging times shorter, and the price more affordable.

    Searching for the super battery

    Traction batteries for electric cars still have potential: charging times will be shorter, ranges will be greater, and service life will be longer. Researchers are working on the future of the cells and thus on electromobility as a whole.

    The success of electric cars stands and falls with battery technology. Basically, the way a battery works is that chemical energy is converted into electrical energy. The process is reversible: you add electrical energy and return the chemical to its initial state. "The beauty of it is: you can design it to be high-energy, highly reversible and highly efficient. This has also made rechargeable batteries interesting for powering cars," says Prof. Martin Winter, head of the Meet Battery Research Center at the University of Münster and director of the Helmholtz Institute Münster.

    What comes after lithium-ion technology?

    Currently, lithium-ion technology is unrivaled in electric car applications. "Quality, performance, service life and cost: no other battery technology satisfies these factors equally," says Andreas Docter, Head of Battery Development at Daimler AG. "The further development of lithium-ion technology has already brought ranges of around 500 kilometers within reach, and charging times can be reduced enormously in perspective - thanks to fast-charging technology." 
    He sees the size of the batteries as one of the biggest challenges with a view to the coming generations of vehicles. But here too, in terms of energy density per volume, lithium-ion technology is currently way ahead.

    Do not confuse feasibility with suitability for series production

    On the path to the super battery of the future, new important milestones keep emerging - one such milestone was recently found by a team of researchers from the University of Texas led by scientist John Goodenough, who is considered one of the fathers of lithium-ion technology. His approach: to replace the liquid electrolyte that transports the ions between the positive and negative poles with a solid, in this case glass. This would make the battery, in which lithium is replaced by the more common sodium, cheaper in price, more durable, and offer higher energy density and safety - because the potential fire hazard of modern e-cars comes primarily from the liquid electrolyte.
    However, technical feasibility should not be confused with suitability for series production. "It takes years to get from the lab to the road," Prof. Winter points out. Other technologies, such as magnesium batteries, promise further advantages, but like metal-air technologies, they are still at the basic research stage.

    Hope lithium metal technology

    To advance lithium-ion technology, experiments are currently being conducted with silicon as an electrode material. This semimetal can significantly increase the capacity of the electricity storage unit and thus the range of electric cars. The disadvantage is durability: With silicon, the volume of the negative electrode increases greatly during charging and shrinks again upon discharging. "In the long term, this leads to damage and cracks in the electrode," says Prof. Ulrich Schubert, a battery expert at the Center for Energy and Environmental Chemistry in Jena.

    Lithium metal technology, which uses metallic instead of ionic lithium, is also promising. The biggest advantage is the higher energy density. If the technology is combined with a solid electrolyte, it is also possible to reduce the risk of fire. However, according to Prof. Schubert, lithium-sulfur batteries will not be ready for series production in electromobility for another 15 to 20 years.

    If we get this right, the future is clearly in favor of the ecological superiority of battery drives.

    Prof. Martin Winterdirector of the Münster Helmholtz Institute

    Great future for the battery

    The degree to which traction batteries improve will make electric cars more suitable for mass use due to optimized practical benefits. "Customer acceptance is decisive for the breakthrough and success of electromobility," says Daimler's Docter. In addition to cost, the eco aspect also plays a key role. "Battery production emits 150 to 200 kg of carbon dioxide per kWh," says Prof. Schubert. Compared with a gasoline-powered car, an electric car will only be in the green zone after around 70,000 to 90,000 kilometers - depending on the current state of the art and the electricity mix.
    His colleague Winter is nevertheless convinced of the future of the battery car - in view of a growing share of regeneratively generated electricity, good recycling possibilities and so-called "second-life options," i.e., a second use, for example, as cellar storage batteries for photovoltaics, as well as the optimization of the battery technology itself: "If we get it right, the future clearly speaks for the ecological superiority of the battery drive.

    Contact person

    Dr. Jakob Seiler

    Head of Coordination Unit for powertrains of the future and Electric Mobility

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