Technology Review has an article on new rechargeable zinc-air batteries - High-Energy Batteries Coming to Market.
A Swiss company says it has developed rechargeable zinc-air batteries that can store three times the energy of lithium ion batteries, by volume, while costing only half as much. ReVolt, of Staefa, Switzerland, plans to sell small "button cell" batteries for hearing aids starting next year and to incorporate its technology into ever larger batteries, introducing cell-phone and electric bicycle batteries in the next few years. It is also starting to develop large-format batteries for electric vehicles.
The battery design is based on technology developed at SINTEF, a research institute in Trondheim, Norway. ReVolt was founded to bring it to market and so far has raised 24 million euros in investment. James McDougall, the company's CEO, says that the technology overcomes the main problem with zinc-air rechargeable batteries--that they typically stop working after relatively few charges. If the technology can be scaled up, zinc-air batteries could make electric vehicles more practical by lowering their costs and increasing their range.
Unlike conventional batteries, which contain all the reactants needed to generate electricity, zinc-air batteries rely on oxygen from the atmosphere to generate current. In the late 1980s they were considered one of the most promising battery technologies because of their high theoretical energy-storage capacity, says Gary Henriksen, manager of the electrochemical energy storage department at Argonne National Laboratory in Illinois. The battery chemistry is also relatively safe because it doesn't require volatile materials, so zinc-air batteries are not prone to catching fire like lithium-ion batteries.