New Lithium-Air Battery Delivers 10 Times the Energy Density

Al writes "A company called PolyPlus has developed lithium metal-air batteries that have 10 times the energy density of regular lithium-ion batteries. The anode is made up entirely of lithium metal, and the surrounding air acts as the cathode, making the batteries incredibly energy dense. Previous efforts to make lithium metal batteries have been stymied by the sensitivity of lithium to water in the air. The new batteries use a sophisticated membrane to protect the lithium anode and PolyPlus has even created a version that works underwater, by drawing oxygen through the membrane. Lithium metal-air batteries could be light-weight power sources for demand for plug-in hybrid vehicles and consumer electronics; IBM also recently announced that it would develop lithium metal-air batteries for the energy grid and for transportation."

Car crash

[tsa]

It would be intersting to see what happens during a car crash in the rain when one of the cars is equiped with those batteries.

Re:Same old story...

[Hadlock]

Exactly. Call me when I can buy AA sized versions of these at WalMart. Or upgrade my Powerbook(Macbook Pro?)'s batteries using this commercially. The budding musician in me wants a long lasting 9v battery that costs less than $4.

Re:Same old story...

[Rei]

Your pessimism is misplaced. Don't you remember cell phones from the early 90s? Those giant bricks? When the then top-of-the-line NiMH battery was introduced in 1989, it boasted 45Wh/kg energy density. Now we have li-ions widely available at 200Wh/kg (4.5x the energy density) and 10x the power density.

For any given tech advance, the odds of it making it to market are low. But there are so many tech advances, many of which you never hear about, that the tech continues to advance at a good clip.

That said, I'm not a really big fan of any X-air batteries. They tend to be inefficient, low power, expensive, and have poor cycle life. There are literally dozens of li-ion advances working toward commercialization that can each 1.5 to 8x the density of either the anode or cathode, so regular li-ion still looks to have a lot of life in it. Also, I'm particularly interested in the recent advancements in lithium-sulfur. Practical lithium sulfur cells are 3-4x the energy density of current li-ion and are efficient and with reasonable power (excepting the unimpressive "stabilized" ones), but they tend to have very short cycle lifes. The University of Waterloo came up with a really interesting approach of wicking the sulfur into the pores of mesoporous carbon, baking it off the outside, and then functionalizing the carbon surface with PEG to repel the hydrophobic sulfur and keep it trapped in the pores so it can't migrate across the membrane and precipitate useless lithium polysulfates (the normal means of capacity loss in LiS). Their results were pretty astounding. In one experiment, they deliberately used an electrolyte known for dissolving polysulfates, thus facilitating capacity loss -- and compared their electrode with a traditional one. In a couple dozen cycles, the traditional electrode lost something like 96% of its capacity. Theirs lost only about a quarter of its capacity.

Rechargeables in "early development"

[michael_cain]

Both articles pointed to by the original post note that rechargeable lithium-air batteries are in "early development". It may be worth noting that zinc-air batteries (fuel cells, more accurately, as these lithium devices are currently) have been available for some years now. The problem is the recharging step, ie, making it a battery instead of a fuel cell. Splitting zinc oxide to get relatively pure zinc back, all within the original container, remains an unsolved problem, in practice. These lithium devices will face the same problem: how do you use electricity to efficiently split lithium oxides to get lithium and oxygen again? If they have indeed solved that problem, and can apply it to other metals, zinc may be a better solution overall, even with somewhat lower energy density. The global mineral reserves are much larger and the problem with water goes away.

Re:Double edged sword

[LordKaT]

My laptop constantly overheats, I mistreak the battery to hell, and still it keeps working.

And millions upon millions of other people have had the same results.

I've only got one piece of advice for you: stop being such a pussy. You're slowing the rest of us down.

Lithium, a limited natural resource?

[mwilliamson]

It seems like this is the holy grail for electric vehicles, and we can finally stop burning dinosaur juice in our little bitty engines and realize the economies of scale of burning dinosaur farts in really big and efficient prime movers. This is all well and good, but how plentiful is lithium, and can it be recycled easily (I suspect yes)? -Michael

Free and "Fun" Experiment

[reporter]

To test the use of the new lithium batteries as bombs, we could just connect the anode to the cathode. Then, we physically observe the explosive force.

I was warned that car batteries can explode if you short-circuit them in this way.

Re:Double edged sword

[need4mospd]

If you think about it, single edged swords are also double edged swords. I mean, it cuts on one side, but not the other....

I think I just blew my own mind.

Why would you bother with Lithium?

[Colin Smith]

Use Sodium instead. There's even more of it in seawater. Sure it's a bit heavier, a bit bigger but a tiny fraction of the cost, and cost is a huge problem with batteries.

 

Re:Explosions

[Rei]

That's simply not true. TNT is less energy dense than aluminum. Which one would you rather be standing next to when a blasting cap is fired on them?

In this case, the energy density of the lithium has nothing to do with how fast it can react. The rate the lithium can burn is exactly the same as the rate in which it can burn in much less energy dense lithium primary cells. And furthermore, while this may be a fundamental problem in "small" devices like cell phones and laptops, large devices, such as electric car battery packs, have ample room for fire prevention, isolation, suppression, and venting systems.

Almost 1/2 the energy density of gas

[flipmac]

This thing 'theoretically' has more than 5kW-hr/kg, which is a big deal considering gasoline has an energy density of 46.9Mj/kg or 12.9kW-hr/kg. Coupling this new battery, when it exists, to a decent brushless DC motors, which are upto 90% efficient, then you'll have a purely electric car that can rival a gasoline powered cars in terms of power and range since IC engines are only 40% efficient (minus more energy that is absorbed in the transmission, etc). And I have a hunch that lithium is more abundant than crude oil. Downside is obviously with the higher energy density, the potential for fire/explosion is bigger. I don't know about you guys, but watching a shorted lithium polymer battery pack is very entertaining and dangerous.

I'll Believe It...

[rally2xs]

When I can buy one. Same sort of "good news" 2 years ago from Stanford when the "nanowire battery" was announced to be capable of 10X a regular lithium cell due to the nanowire construction of the anode. No mention that they also needed a cathode breakthru to achieve the 10X. Without a cathode breakthru, you get 3X. Big whoop. Good, but no cigar. An electric car needs the whole 10X. But guess what - where is that battery now? It's being "developed" by the researchers in question not at Stanford but at a university in Saudi Arabia. Does Saudi Arabia have an interest in bringing to market a device that would preclude the need for their chief export? Not hardly. I wouldn't be either of those guys for all the tea in China. They're likely as not to have a beheading "accident" before this research is done, with the very least that could happen being a sabotaging of the product. We'll see how this new battery goes - or if it goes to Saudi Arabia too.

Air pollution?

[w3woody]

Any time chemicals interact with air, it strikes me there is the potential for air pollution.

Is that the case here? I mean, in theory the chemistry may not result in pollution, but in the real world it only takes a fraction of a percent of the chemistry to take an alternate reactive path to result in unexpected or unwanted impurities...

Underwater use?

[Locke2005]

Is energy density really a top requirement for submarine use? It seems to me most submersibles contain thousands of pounds of ballast anyway -- might as well carry heavy batteries. Plus "reacts violently to any contact with water" doesn't really sound like a property I would want in my submersible battery. Unless these are significantly cheaper or more reliable than li-ion, they don't sound like a win underwater. In cell phones and laptops, however, weight and volume are king, and any technology that stores more energy in less weight or volume will be an economic success.

Re:Air pollution?

[reginaldo]

I don't think so, solely based on the fact that the lithium oxide crystals that are created would stay within the battery. However, here is a good read about the toxicity of lithium compounds. Sounds like if lithium compunds are released, we would have a lot of very mellow people who have to pee a lot.

The toxicity of lithium compounds is a function of their solubility in water. Lithium ion has central nervous system toxicity. The initial effects of lithium exposure are tremors of the hands, nausea, micturition, slurred speech, sluggishness, sleepiness, vertigo, thirst, and increased urine volume. Effects from continued exposure are apathy, anorexia, fatigue, lethargy, muscular weakness, and changes in ECG. Long-term exposure leads to hypothyroidism, leukocytosis, edema, weight gain, polydipsia/polyuria (increased water intake leading to increased urinary output), memory impairment, seizures, kidney damage, shock, hypotension, cardiac arrhythmias, coma, death. (Sax, Dangerous Properties of Industrial Materials, eighth edition)

Re:Free and "Fun" Experiment

[Khyber]

Nope. Not unless you have a Class-D extinguisher made for putting out metal-based fires like magnesium, lithium, sodium, etc.