Scientists at the Fraunhofer Institute for Environmental, Safety and Energy Technology UMSICHT in Oberhausen, Germany have made an important breakthrough with their development of a redox flow battery.
The scientists have succeeded in significantly increasing the size of the stack and, with it, its capacity. A new design has allowed them to produce stacks up to 0.5 square meters in size.
This is eight times larger than the cells in previous systems, and results in power up to 25 kW. The Fraunhofer prototype has an efficiency of up to 80%, and can take a load of up to 500 amps of current.
Redox flow batteries could offer an effective way to balance out fluctuations in the supply of renewable energy and thus guarantee its constant availability. The batteries store electrical energy in chemical compounds, the liquid electrolytes.
The electrolytes are charged and discharged in small reaction chambers. Several of these cells are lined up in stacks. However, the batteries that are currently available on the market, which are roughly the size of A4 paper (1/16 square meters), can only generate 2.3 kW.
UMSICHT experts are now working together with colleagues from the Fraunhofer Institutes for Chemical Technology ICT and for Solar Energy Systems ISE to conduct intensive research into redox flow batteries as part of a project funded by the Federal Ministry for the Environment, Nature Conservation and Nuclear Safety (BMU).
The research work is carried out at the institute in Oberhausen, home to one of Europe’s largest test laboratories for redox flow batteries. “Successfully redesigning the battery stacks was an important step in developing redox flow batteries that could, for example, supply 2000 households with electricity,” says Dr. Christian Dötsch Division Director Energy at Fraunhofer UMSICHT.
This would require a capacity of around two megawatts, so the next fixed objective is to develop a stack that is two square meters in size and has a capacity of 100 kW.