By Jeff St. John
Financial terms of the deal weren't announced, but BASF said it would put its engineers on the task, as well as provide materials and subsystems to "help BASF to assess today's and future potential of this technology."
Metal-air batteries generate power by exposing metal and an electrolyte to oxygen, oxidizing the metal and releasing energy (see Electricity From Air and Zinc? A Growing Chorus Says Yes).
They can offer many multiples the energy density of lithium-ion batteries, but recharging them is a challenge, as the chemical process they use to generate power is hard to reverse. That's limited their commercial appeal to single-use purposes such as hearing aid batteries.
ReVolt says it solves the recharging problem with a bi-functional air electrode that can reform the oxygen and metal used to power the first reaction in a more energy-efficient way. It also doesn't degrade the materials involved, it says, resulting in a rechargeable battery with about three times the energy storage of its lithium-ion contenders.
ReVolt raised €10 million ($14 million) in a January second round of funding, adding to a 2005 €7 million round and a €1.5 million seed round of funding.
It isn't alone in the quest for the rechargeable metal-air battery. Lawrence Berkeley National Laboratory spinout PowerAir has what it calls zinc-air fuel cells, given that they are "recharged" by removing spent materials and adding fresh ones, as a fuel cell does. It's looking at ways to use the leftover zinc oxide as well.
Lithium-air batteries could offer even greater energy densities, researchers say. Berkeley-based startup PolyPlus is working on lithium air batteries, along with ones using seawater or sulfur as electrolytes, something it says is made possible by its "protected" lithium electrodes that don't chemically mix with the electrolyte. According to CNET, it is developing lithium-air batteries with Quallion, a lithium-ion battery manufacturer with medical device and military customers now seeking to expand into powering idling trucks (see Quallion Seeks DOE Grants For 'Anti-Idling' Batteries).
IBM also is researching lithium-air batteries, looking at ways filters it has developed for water purification at its Almaden Research Center in San Jose, Calif.,could be applied to the recharging challenge (see IBM Delves Into Lithium-Air Batteries, Water-Cooled Supercomputers).
ReVolt will be one of 25 European and Israeli green technology startups presenting at the European Tech Tour Cleantech Summit next week (see Green Light post). Perhaps more details on its commercialization plans will emerge then.