Redox flow batteries offer an effective way to balance out fluctuations in the supply of renewable energy and thus guarantee its constant availability.
Researchers all over the world are working towards finding alternate sources of generating electricity such as solar and wind energy. It is important to have powerful electric energy storage devices to level out corresponding irregularities in the power supply. Fraunhofer scientists have recently made an important breakthrough with their development of a redox flow battery that reaches stack power up to 25 kW, with a cell size of 0.5 square meters. This is eight times larger than the previous A4-sized systems. The new battery will be presented for the first time at the Hannover Messe trade show from April 8–12.
Redox flow batteries 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.
Scientists at the Fraunhofer Institute for Environmental, Safety and Energy Technology UMSICHT in Oberhausen, Germany, 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. Scientists will showcase this battery at the Energy Alliance’s Fraunhofer booth at Hannover Messe (Hall 13, booth C10). The prototype has an efficiency of up to 80 percent, and can take a load of up to 500 amps of current.
So how have the experts managed to increase the size and capacity so remarkably? Scientists began by testing new membrane materials and researching battery management and battery design. Flow simulations helped them to optimize the cell structure. A complete redesign of the battery followed which enabled the Fraunhofer team to make their breakthrough. “The biggest challenge we faced for producing batteries with this level of performance was the development of a completely new stack structure andthe scale-up,” explains Dr. Jens Burfeind, Group Manager for Electrochemical Storage Systems at Fraunhofer UMSICHT.
