Lithium-air batteries' high energy density could extend range of electric vehicles

Feb 01, 2011 by Lisa Zyga weblog
A lithium-air battery developed at MIT. Image credit: Patrick Gillooly/MIT.

(PhysOrg.com) -- For today's electric vehicles that run on lithium-ion batteries, one of the biggest downsides is the limited range between recharging. Over the past several years, researchers have been working on an alternative battery called a lithium-air battery. These batteries could significantly increase the range of electric vehicles due to their high energy density, which could theoretically be equal to the energy density of gasoline.

At the fall meeting of the Materials Research Society in Boston, Ming Au, a scientist from the Savannah River National Laboratory in Aiken, S.C., said that no other known battery has as high of an as lithium-air batteries. Researchers estimate that these batteries could hold 5-10 times the energy of lithium-ion batteries of the same weight, and twice the energy for the same volume.

Lithium-air batteries have an made of lithium and an “air cathode” made of a porous material that draws in oxygen from the surrounding air. When the lithium combines with the oxygen, it forms lithium oxide and releases energy. Since the oxygen doesn’t need to be stored in the battery, the cathode is much lighter than that of a lithium-ion battery, which gives lithium-air batteries their high energy density.

At the meeting, Au said that his research group has demonstrated a coin-sized rechargeable lithium-air battery with a current density of 600 mAh/g, which is much higher than the current densities of 100 to 150 mAh/g of lithium-ion batteries.

But one of the biggest challenges facing lithium-air batteries is their limited number of charge/discharge cycles. Whereas lithium-ion batteries can be recharged more than 100,000 times, Au’s lithium-air battery can be recharged only about 50 times. Although single-use lithium-air batteries are already being used, for example to power hearing aids, require batteries that can be recharged thousands of times.

The biggest problem with recharging lithium-air batteries is that it’s very difficult to convert the lithium oxide back into lithium. Currently, researchers can do this only by using catalysts, and even then some of the lithium oxide cannot be converted because it builds up in the . Researchers also face challenges in speeding up the recharging process and in keeping water vapor out of the oxygen, since lithium reacts violently with water.

At the meeting, Au said that rechargeable lithium-air batteries would probably not be commercially available for several years, noting that lithium-ion batteries were first proposed in the 1970s but not commercialized until 1997. (Lithium-air batteries were first demonstrated in the mid-‘90s.) Au added that a “big investment from the government or some corporation” would have to be secured for developing a commercial product.

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More information: via: IEEE Spectrum

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User comments : 8

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wealthychef
3.4 / 5 (5) Feb 01, 2011
So what's this article about anyway? "This battery could be great if it could be recharged more. But it can't. But wouldn't it be great if it could?" Sigh.
Edylc
1.5 / 5 (4) Feb 01, 2011
They made batteries that are super amazing way back.. and then GM or somebody bought the patents and shelved em. Watch "Who Killed The Electric Car" ... it's really really annoying the way it works.
Sin_Amos
not rated yet Feb 01, 2011
So what's this article about anyway? "This battery could be great if it could be recharged more. But it can't. But wouldn't it be great if it could?" Sigh.


Double sigh. We have so much potential to fail.
antialias
5 / 5 (4) Feb 02, 2011
That's just how science works. You solve one problem at a time. This reseach solved the problem of energy density for batteries (which is awesome!). NOW they can start working on making it have more recharge cycles.

Before the first step was completed working on the second one would have been pointless. You have to realize that scientists are not miracle workers and don't spit out revolutionary designs with the flick of a wrist like in Hollywood super-hero movies.

Science is a slow, deliberate process in which many small steps lead to advances - not huge leaps and bounds. The time between starting a project and having something commercial come of it is measured in decades for most products. You need to realize this and not slag off great science (like in this article) because it doesn't provide all the abilities you wish for in the first prototype.
Bob_Kob
not rated yet Feb 02, 2011
Well thats the problem, if they havn't found a solution then stop flirting with us like a bimbo that doesn't put out.
msadesign
5 / 5 (2) Feb 02, 2011
Well. Personally I like watching me some bimbo, whilst contemplating the quickest path to getting a bit closer to said bimbo…sorta like science.
antialias
5 / 5 (2) Feb 02, 2011
Well thats the problem, if they havn't found a solution then stop flirting with us like a bimbo that doesn't put out.

You are not being flirted with. You are not the target audience for the (original science) article.

It was published in a scientific paper/journal for the benefit of other scientists working on the same subject or in closely related fields.

It's important to publish every small step, so that others might build on it (or catch up more quickly if they haven't gotten to the point you're at). The benefit is that many scientists in different institutions can work on stuff and be more or less on the same level of knowledge at all times. There's also the effect of 'cross pollinating' your ideas with stuff you read.

This increases the chance of getting the entire field advanced more quickly (and helps those who might be stuck with a particular problem to join in again).

Physorg just collects these papers and presents them in layman friendly terms.
SteveL
5 / 5 (2) Feb 03, 2011
Some team may come along and discover how to make a lithium alloy or treated foam, to increase to surface area and power desity. Another may come along and discover that a particular light or electronic frequency helps to restore the lithium oxide back to its initial form, while still another group might suggest they apply a microfilter to the air source that allows oxygen through to the battery but not the water vapor or other contaminants. Discovery is often a three steps forward - two steps back process. Just by getting the news out providing information on the advances made can invite assistance from other skill sets.

In order to be really good people often focus on a particular skill set, and tend to be somewhat less capable in others. By getting the progress published others who may have highly developed skill sets in another field may be able to contribute.

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