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First zinc-air batteries will hit next year in small form factors

Rechargeable batteries are used in so many different products that we use today – everything from our computers and mobile phones to our cars have batteries inside. One of the major areas of research is in new battery technologies that will increase the run time of electrical devices and make safer batteries.

Lithium-ion rechargeable batteries have been on the market for a long time and are prone to problems. The batteries, for instance, were the cause of massive recall several years ago after they were overheating in notebooks which in turn caused fires. One of the more promising new battery technologies being researched are zinc-air batteries.

These batteries are cheaper and have a significantly larger capacity for storing energy than existing lithium-ion batteries. Physorg reports that the average lithium-ion battery stores only a third of the energy that zinc-air batteries are capable of storing and cost about twice as much as the zinc-air counterpart.

A Swiss company called ReVolt plans to release a zinc-air battery next year. At first, the batteries will be small units that will be used in hearing aids. Later the batteries will come in larger forms for mobile phones and much later, the zinc-air battery will find its way into electric vehicles.

The zinc-air battery was developed by a firm called SINTEF in Norway and ReVolt was formed to market the battery. In a zinc-air battery, oxygen from room air is used to generate current. The air is used as an electrode and the battery contains an electrolyte and a zinc electrode in a casing that is porous and allows air inside. The zinc-air battery is much safer than lithium-ion batteries because there are no volatile materials inside the battery that could possibly catch fire.

The zinc-air battery produces electricity when the air electrode is discharged with the help of catalysts producing hydroxyl ions in the aqueous electrode. The zinc electrode then gets oxidized and releases electrons to form an electric current. When the battery is recharged, the process happens in reverse and oxygen is released into the air electrode.

The challenge for the researchers was to devise a method where the air electrolyte wasn’t deactivated in the recharging cycle to the point where the oxidation reaction slowed or stopped. The slowing or stopping of the oxidation reaction reduced the number of times that the zinc-air battery could be recharged.

Physorg reports that prototypes of the zinc-air battery have been tested through more than a hundred charge and discharge cycles. ReVolt hopes to increase the number of charge and discharge cycles to the 300 to 500 range. That number would make the batteries useful for cell phones and other electronic items that are recharged frequently.

The zinc-air batteries ReVolt is working on are also being developed for future use in electric vehicles. Before that point can be reached the batteries have to reach the point of being able to withstand up to 10,000 charge cycles.

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By CZroe on 10/31/2009 9:53:23 AM , Rating: 2
I'm still hoping for a huge breakthrough in ultra-capacitors. Why? In a fuel-burning car, you run out of fuel and it only takes minutes to top back up and continue on to your destination. In an electrical vehicle, unless recharge times are significantly shortened, your destination better be within that range because your range effectively ENDS unless you plan to spend time recharging high-capacity battery packs. Even within range, your destination has to have the capacity to recharge and get you home or else your range is further halved. If you spend 8hrs at work, that may be plenty of time to charge for the trip back, but what if you were picking the kids up from school or only spending half an hour in the grocery store?

Keep in mind, while the range problem halving if your destination has no recharge capacity may not be a problem in the future, recharge time to extend your range still may be. Think about it... there may be a "hydrogen highway" for refueling hydrogen powered vehicles to cross the state of CA, but anything like that for straight EVs would still either require many multi-hour pit stops for recharging or swapping an expended cell for a pre-charged one.

Ultra-capacitors, on the other hand, may charge faster than a typical vehicle even could refuel.

By mindless1 on 10/31/2009 6:31:52 PM , Rating: 2
There won't be a huge breakthrough with ultracapacitors very soon, and the problem with charging them as quickly as you'd like is that the infrastructure to supply such massive amounts of current won't be cheap, in both delivery to the (automobile) and it's supportive recharge/safety circuitry.

If it weren't for these factors, today's electric cars would already be recharging much faster than they do. Consider that generally speaking given good sensing and protection circuitry, you can recharge as fast as you can discharge minus a few percent, meaning if your car can drain the battery in 2 hours or less (consider highway driving at 70MPH, that's already 140 miles), the battery is theoretically capable of recharge in little more than that but is actually capable of even faster recharge as the discharge limit wasn't the battery it was the motor and speed limit.

By CZroe on 10/31/2009 6:48:56 PM , Rating: 2
Who wants to spend a "little more than two hours" refueling their car every two hours in a cross-country trip? That'll turn a two-day trip into a week!

Anyway, an slowly charged ultracapacitor could quickly charge another ultracapacitor. The massive discahge could be handled with a massive connection or made up of many connections to many smaller ultracapacitor cells. It could also be regulated. Just because it's possible to charge all at once but unsafe doesn't mean that you have to find a safe way to do it all at once... you don't try to dump 10 gallons in your car simultaneously. Also, the fill-up isn't instant, but it is fast (compared to charging a battery). Charging an ultracapacitor, similarly, just needs to be somewhat more comparable to filling up vs charging. That means it could take, say, 10 mins instead of a 5min fill up or two hour+ charge.


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