Researchers at the Fraunhofer Institute for Chemical Technology (ICT) have developed an innovative battery circulating redox ( “redox-flow“). This type of battery has the following advantage: when it is discharged, the electrolyte fluid from which it operates can be simply exchanged against an electrolyte nine, which requires as much time as filling a gas tank.
To meet the challenge to move one million units by 2020 in Germany, one of the problems that remain to be addressed is that of energy storage. One possible solution is to use lithium-ion batteries, however they currently charge lasts a few hours, which represents a significant time for drivers. Batteries circulating redox represent a possible alternative. “These batteries are based on liquid electrolytes. It is therefore possible to recharge in minutes at a station: the electrolyte is discharged evacuated and replaced by an electrolyte charge,” said Jens Noack, an engineer at ICT. The electrolyte was unloaded at the station could be recharged, for example via a wind or solar.
The principle of these batteries is not new: two liquid electrolytes containing metal ions, separated by a membrane that lets the protons flow through electrodes made of porous graphite sheets. During this exchange of charges, electricity flows through the electrodes.
So far, batteries circulating redox presented a drawback: the amount of energy they could store was much smaller than that stored in the lithium-ion batteries. The autonomy of the vehicle and was about 25 km, a quarter of the vehicles powered by lithium-ion batteries, which multiplied the frequency of recharging 4. “We were able to increase autonomy by four or five, so we approached the range of vehicles powered by lithium-ion batteries,” continues Jens Noack. The prototype of a cell already exists, and now German scientists want to assemble different cells in a battery, then optimize.
This development is carried out jointly with researchers from the University of Applied Sciences Ostfalia and Brunswick in Wolfenbuttel. Electric motors and storage means are tested on vehicles scale models 1 / 10 (or a size of one tenth of the usual vehicle). A battery of redox flow has already been integrated into a vehicle and model will be presented from 13 to 15 October 2009 at the show eCarTech in Munich. In the coming years, researchers have ICT integrated the new battery with greater capacity in a vehicle.