Rechargeable Zinc-Air Batteries

Electricity has a lot of attractions as a power source.  It can be generated in a wide variety of ways, including “green” methods like hydropower, solar power, and wind.  One of the sticking points with electric power, though, has always been how to store it.  The storage technology has come a long way, both with improved batteries and other devices, like ultra-capacitors.  Yet anyone who routinely lugs around a laptop computer, cellphone, and other electronic gadgets knows that lighter, smaller energy storage devices would be welcome.

Back in June, I wrote a note about new developments in lithium-air battery technology, in which I mentioned the use of disposable zinc-air batteries for devices like hearing aids.  Now Technology Review is reporting that a Swiss company, ReVolt Technology, is developing rechargeable zinc-air batteries.  Its first products will be small “button” batteries, similar in size and capacity to the disposable zinc-air batteries now on the market, but it has bigger plans:

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.

As with lithium-air batteries, the advantage of using air as one of the reactants is that it need not be stored within the battery itself, since it can be readily obtained from the environment (at least for terrestrial applications).  This leads to higher energy density: more power per unit of weight.  Compared to lithium-based batteries, zinc-air chemistry is attractive because there is much less risk of overheating and fire.  The problem to date has always been that it was not possible to get more than a few charge / discharge cycles from a zinc-air battery, because of degradation of the electrodes.

The company  claims that, by using a modified catalyst together with gelling and binding agents, it has produced prototype cells that last more than 100 charge / discharge cycles, and hopes to increase that to 300-500 cycles, which might make these zinc-air cells very competitive for cell phones, for example.  The company is also working on a new battery design for use in electric vehicles, but it will be a few years before these are ready for real-world trials.



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