Redox-Flow batteries to power 2,000 households

Above is a schematic of a redox-flow cell detailing the technology.

The energy storage units operate in conjunction with an electrolyte tank for each of the two electrodes.

The liquid electrolytes (e.g., vanadium) contain metal ions that flow through electrodes made of porous graphite fleece, separated by a membrane which is proton-permeable.

During this exchange of charge a current flows over the electrodes which can be utilised.

The battery can provide unlimited capacity simply by using larger and larger storage tanks, and it can be left completely discharged for long periods with no ill effects. And because both electrolytes contain the same materials they do not contaminate the cells and the tanks if the electrolytes become mixed. They only need to differ in terms of ion charge or oxidation stage.

“This makes it possible to build very robust and durable batteries – a decisive advantage of this battery technology,” emphasizes Fraunhofer’s Dr. Tom Smolinka.

On the downside, redox flow battery technology has relatively poor energy-to-volume ratio, and the system is more complex than standard storage batteries. For instance, insuring that the vanadium fluid flows smoothly through the large membranes and past the felt-like carbon electrodes in the cells themselves is a challenge, according to the researchers.

Fraunhofer researchers are convinced that the advantages of redox flow batteries will drive development, and in the next five years larger demo systems will be built and quickly followed by commercial redox-flow batteries.

Eventually, the focus will move on to the development of redox-flow batteries as a feasible technology for electric cars.


Giant futuristic batteries to power 2,000 households | ZDNet