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."

Comments

Same old story...

[abigsmurf]

"it expects these batteries to be on the market within a few years"

Just like those ultra efficient, cheap, solar panels we've been promised 'next year' each year for the last decade.

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.

Re:Same old story...

[Daimanta]

Don't be silly! Functionalizing is a perfectly cromulent word.

Re:Same old story...

[berend botje]

I stand corrected. You and OP used a perfectly normal word. You are right in your assertion I should have looked it up before posting.

Thanks for expanding my vocabulary.

Re:Same old story...

[Rei]

Come now, mods, that wasn't a troll. It's hard for people to admit mistakes in a discussion (I myself fall into that same trap from time to time). Don't discourage it by calling them trolls for doing so.

Got a hammer?

[tomhudson]

I'm no battery scientist, but I wonder if these batteries will be more or less safe compared to the lithium-ion batteries. I guess I could go read the article but...

Anything that breaks the membrane and allows moisture to come into contact with the anode will start a nice fire. Or you can microwave them. Or blend them.

First they came for boxcutters, but I wasn't a terr'rist, so I didn't say anything.
Then they came for hammers, but I wasn't a terr'rist, so I didn't say anything.
Then they came for screwdrivers, but I wasn't a terr'rist, so I didn't say anything.
Then they came for microwaves, but I wasn't a terr'rist, so I didn't say anything.
Then they came for blenders, but I wasn't a terr'rist, so I didn't say anything.
Then they came for can-openers, but I wasn't a terr'rist, so I didn't say anything.
So here I sit starving, unable to open this frigging can of food, and even if I could, I'd have to eat it cold because I can't nuke it and without tools I can't fix the furnace. Now if only I could find a rock and a lithium battery, I'd be able to cook it!

Re:Explosions

[MyLongNickName]

Or if you even looked at the article, you would see a demo of it running underwater.

Re:Double edged sword

[evilviper]

Energy density is a double edged sword.

No, it isn't.

But there are inherent dangers. The current Lithium-Ion batteries are pretty dangerous when they are mistreated.

Lithium-Ion batteries are dangerous because of very low internal resistance. ie. They can dump a large amount of current in a very short time. This is completely independent of energy density, and future designs could well have higher energy density with less danger of thermal runaway.

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:Explosions

[Locklin]

Diesel fuel has a very high energy density and very little explosive potential. The danger comes not from the contained energy, but how fast that energy can be released.

Energy Density Fears

[Burning1]

A lot of people are raising concerns about the risk associated with increasing the energy density of the battery.

I would like to point out that it's difficult to directly compare the risks of two fuel sources without knowing how quickly the energy can be released, and under what conditions it can happen.

For instance, I enjoy working with motorcycles, which typically carry 2 major energy sources: A battery, which supplies starting and auxiliary power, and gasoline, which supplies primary power (including the power required to charge the battery.)

The gasoline in the tank has a far greater energy density and far higher energy potential than the battery, but of the two, the battery poses the greatest risk of injury and explosion.

The gasoline can certainly burn, but will only explode under very specific conditions. The conditions required to set it burning are also very easily removed. In fact, I'm far more concerned about the chemical damaged caused by exposing fuel to skin than I am about the risk of fire or explosion.

On the other hand, I work around the battery with wrenches that are typically grounded against the frame while in use. Even with a disconnected battery, I've had cases (while working on a car) where the wrench contacts the positive terminal of the disconnected battery, creating very heavy gauge short circuit between the terminals. The resulting release of energy will cut through metal and cause severe burns. Likewise, if overdrawn, the battery can release hydrogen which can either vent and ignite, or build internal pressure causing the battery to explode.

An interesting example of a substance that is explosive, has a high energy density, and is safe is C4, which can actually be used to cook food if burned, but will not explode without a blasting cap.

So... Are these batteries a risk? Perhaps. We should look into that. But it's best not to cry about the sky falling without first investigating the matter.

Re:Explosions

[Anonymous Coward]

I believe the summary is the first time I've ever seen "sensitivity" used as a synonym for "tendency to explode violently."

My former girlfriend was a very sensitive person.

It never occurred to me before, but now that you mention it, I think this is exactly what she meant by the term.

Re:Lithium, a limited natural resource?

[trybywrench]

It's Bolivia that has all the Lithium. They are already freaking out about corporations raping their country for profit. IIRC Bolivia has started working on putting policy in place to keep from getting screwed over by large mining firms.

"Like many other producers of crude oil, Bolivia finds itself in a frustrating situation regarding its processing and the refining of its raw materials. It finds company in the history of the incumbent automobile fuel source, petroleum. There is a great deal that the Bolivians could learn from the Saudis regarding what they should do with its lithium reserves and how to extract them. To achieve this, Bolivia will want to strive to find the answer to a number of questions with which the Saudis have dealt over the years, and continues to deal with, such as how wealth will be distributed if the commodity is nationalized, how to maintain a balance between maximum production and environmental stability, and what will stabilize the economy once the commodity is exhausted."

http://www.coha.org/2009/02/lucky-bolivia-and-the-future-of-lithium-in-the-world-economy/

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.

Re:I'm so happy 'cause today I found my friends

[Rei]

However, the big catch is that we can't really produce enough Lithium to make all those batteries.

God, that myth just won't die, will it?

But there's probably no practical way to extract it.

Of course there is. There are dozens of ways. Here's one -- $22-$32/kg. Given that 1kWh of automotive li-ion batteries takes 1-2kg of lithium carbonate and costs about $500, that's a pretty minor cost. More expensive than the surface-mined stuff, mind you (which runs $5-8/kg), but eminently affordable.

Re:Explosions

[Rei]

If you put aluminum in a dust form and then aerosol it, it'll be much worse;

Irrelevant. That *block of aluminum* has more energy density than TNT. *So does aerosolized aluminum*, but so does the block. And it has more energy than gasoline per kilogram, too.

Just because something has high energy density does *not* mean it has a realistic way to release that energy rapidly. And the amount of energy contained within the chemicals that make up a battery (releasable by burning) are often way more than the amount of electrical energy stored in the battery, so saying that because the electricity stored went up 10fold means somehow that the chemical energy that would be released in a fire went up 10fold is just wrong.

If I added a resistor to the inside of a battery so as to waste most of the power of the battery, causing the energy density of the cell to decrease tenfold, would it somehow suddenly become ten times less flammable? If I took the resistor away, would it suddenly become ten times more flammable? Don't act like that's far-fetched, because that's very similar to how a lot of battery improvements work -- lowering the internal resistance, making sure that more of the material within can take part in the desired electricity-storage reactions, and so forth.

There are some incredibly flammable low-energy density batteries, and incredibly fire-resistant high energy density batteries out there. Heck, the Zebra battery has almost the energy density of the lower-end li-ions, and it operates at temperatures of hundreds of degrees in *typical usage*. The amount of electricity stored is simply not inherently correlated with the energy density.

Re:Free and "Fun" Experiment

[Smidge204]

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

All batteries have internal resistance which naturally limits the amount of current, and therefore power, they can put out. They are unlikely to "explode" in the same way a firecracker explodes... at least from the chemistry alone.

What can happen, though, is the high power draw form shorting a battery will cause a LOT of heat generation. The stuff inside the battery expands with this heat, maybe even vaporizes, and if the battery casing is relatively inflexible it could burst. Bursting is not *quite* the same as exploding.

BUT! Lithium is nasty stuff. If a lithium battery bursts, exposing the lithium directly to the air, then you might get some real pyrotechnics going.
=Smidge=

Don't use these Batteries in Space!!!!

[jameskojiro]

I needed some batteries for the life support systems on my spacesuit, so i went and bought some of these new fangled Lithium-Air Batteries and they don't work worth a crap. They worked fine in the airlock but as soon as I stepped out on my space walk I was gasping for air as my life support system inexplicably shutdown.
.
These Batteries are Horrible, just Horrible!!!! I have to trust my life to batteries for supplying me with Oxygen and keeping my temperature constant.
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Two space gloved thumbs down!
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