Renewable energy sources do not always deliver the same amount of electricity, so the energy has to be stored temporarily in batteries. Efficient battery systems are also required for technologies such as electric mobility. The mains electricity network is not designed for 350kW quick charging stations, for example, nor is there a mains network at all the locations where stations of that sort would be useful. Lithium ion batteries are only suitable for storage up to a point because of their low cycle stability: if they are charged and discharged two to three times a day, they will only last two to three years. Redox flow batteries, on the other hand, offer high cycle stability, do not catch fire and are recyclable; their capacity and output can be adapted easily. They are therefore particularly suitable for applications in which heavy demands are made on the battery.

Scientists at the Fraunhofer Institute for Environmental, Safety, and Energy Technology (UMSICHT) in Oberhausen have now been able to cut the manufacturing costs of what until now have been expensive systems. The innovative redox flow batteries are being produced and marketed by the Fraunhofer spin-off Volterion in Dortmund.