Phinergy is testing out a retrofitted Citroen C1 that has a lithium-ion battery in the trunk as well as one of Phinergy's 55-pound batteries serving as a range extender. The battery, reports Bloomberg (and translated from science lingo into something more digestible by Green Car Reports), contains aluminum plates that serve as an anode to the air's cathode, letting the driver fill the battery with water every two-hundred miles or so to create a recharge. Each plate provides about 20 miles worth of driving (they would have to be replaced and Phinergy hasn't gotten into what that entails).
The major advancement by Phinergy, which gets funding from Israel's Ministry of Energy and Water Resources, is that its technology prevents carbon dioxide from hindering the aluminum-air cells. The product may be commercially available by 2017.
The upshot is that the battery can serve as a 1,000-mile range-extender to the li-ion battery's 100-mile range, which would make for a pretty nice West Coast road trip a few short years from now. Maybe.
Check out the Bloomberg video below.