PowerSource

In general, batteries are good at storing energy and not so good at charging or discharging rapidly. Supercaps, on the other hand, are excellent at fast charging/discharging, but not so good at storing energy over a period of days or months. Ideally, for energy storage and delivery for the next generation of electric vehicles, you need both characteristics. After all, it takes just 5 minutes to gas (or diesel) up a conventional car. The 4 – 10 hours it takes to re-charge today’s batteries is a sticking point for EVs of the future.

The redox battery (which is shorthand for reduction-oxidation flow battery) offers a novel solution to the problem of charging times: Replace the discharged electrolyte with a fully-charged electrolyte much as you’d fill up an empty tank with more gasoline. Here’s the Wikipeida description:

“A flow battery is a form of rechargeable battery in which electrolyte containing one or more dissolved electroactive species flows through an electrochemical cell that converts chemical energy directly to electricity… Flow batteries can be rapidly "recharged" by replacing the electrolyte liquid (in a similar way to refilling fuel tanks for internal combustion engines) while simultaneously recovering the spent material for re-energization.”

The problem with redox batteries is that they can’t store as much energy as, say, a lithium ion battery –only a quarter as much. However, researchers at the Fraunhofer Institute for Chemical Technology ICT have refined the process for a redox cell that allows a four-to five-fold increase in energy storage, making it on par with lithium ion batteries. (No details so far on the exact refinements.)

The German government is aiming for one million electric cars being sold in Germany by the year 2020.