Slashdot Log In
World's First Battery Fueled By Air
Posted by
CmdrTaco
on Thu May 21, 2009 08:26 AM
from the i-produce-tons-of-hot-air dept.
from the i-produce-tons-of-hot-air dept.
Hugh Pickens writes "The Telegraph reports on the revolutionary 'STAIR' (St Andrews Air) battery could now pave the way for a new generation of electric cars, laptops and mobile phones. The cells are charged in a traditional way but as power is used an open mesh section of battery draws in oxygen from the surrounding air that reacts with a porous carbon component inside the battery, which creates more energy and helps to continually 'charge' the cell as it is being discharged. The battery has a greater storage capacity than other similar-sized cells and can emit power up to 10 times longer. 'The key is to use oxygen in the air as a re-agent, rather than carry the necessary chemicals around inside the battery,' says Professor Peter Bruce of the Chemistry Department at the University of St Andrews. 'Our target is to get a five to ten fold increase in storage capacity, which is beyond the horizon of current lithium batteries.'"
Related Stories
This discussion has been archived.
No new comments can be posted.
The Fine Print: The following comments are owned by whoever posted them. We are not responsible for them in any way.
Full
Abbreviated
Hidden
Loading... please wait.
Question (Score:5, Interesting)
Would there be any danger of using this in a confined space? Any clue on how much oxygen this thing is churning through?
Re:Question (Score:5, Funny)
Would there be any danger of using this in a confined space?
Only if you had beans for dinner.
Parent
Re:Question (Score:5, Funny)
At least, that is unless you had some kind of highly complex extraction [bizfriendmarketing.com] device [toolstation.com] to remove the oxygen build up.
Parent
Re:Question (Score:5, Interesting)
Ummmmm... I am more referring to its consuming oxygen that might otherwise be used for breathing.
Parent
Re:Question (Score:4, Funny)
THE WALLS ARE CLOSING IN, MAN!
Parent
Re:Question (Score:5, Informative)
I don't think it's that awesome. Air batteries (which are nothing new, BTW), tend to suffer from poor cycle lifes, poor power density, and very low efficiency. Often these "breakthroughs" aren't as impressive as they at first sound.
Now, that said, the other recent battery breakthrough -- on the Li-S front -- really does look as impressive as it sounds. I read through the paper on the research the other day as "light reading" at the dentist's office ;) Li-S's big problem has long been its really atrocious cycle life. It has great energy density, good power density, and very good efficiency, but the cycle life is a killer. And the variants they tried to improve cycle life really shot the energy density.
The reason it has these cycle life problems is because of how it works: you have sulfur in a carbon matrix (needs a conductive matrix because sulfur is an insulator) on one side of a separator film and metallic lithium on the other. The lithium ions migrate across the membrane and bond with the (insoluble) sulfur cathode to form (insoluble) Li2S; then, when running the cell in the other direction, the Li2S is split and the ions migrate back to the metallic anode. But there are intermediary reaction products -- various lithium polysulfides -- and these *do* tend to be very soluble. So, some of the polysulfides dissolve into the electrolyte, migrate across the membrane, and precipitate out on the other side and are rendered useless.
The new technique is pretty clever. They start by making a form of mesoporous carbon. This is made kind of like aerogel, via nanocasting, and it's covered in really deep pits. They then mill and then heat together the sulfur and carbon. The sulfur, having low surface tension, wicks into all of the pore space, with only a small amount of room left over to account for expansion. They then bake the composite at 155C, which boils all of the sulfur off the surface, leaving it only in the pits. So when the polysulfides form, they have a lot of trouble migrating out of the carbon.
That alone is a big improvement, but they took it a step further. The polysulfides are hydrophobic, so they bonded polyethylene glycol to the exposed surface of the carbon to make it repel the polysulfides. So now they have even more trouble migrating out of the pore space. To show how well they have them trapped, they took a traditional Li-S cathode and used a worst-case electrolyte -- something that loves to dissolve polysulfides. After 30 cycles, 96% of the sulfur was gone. With their cathode in the same worst-case situation, only 26% was lost.
In normal coin cells, their tests showed an initial capacity of around 80% of the theoretical maximum, falling about 15% in the first few cycles and then plateauing, nice and stable. The theoretical maximum for Li-S, if you discount everything but the sulfur, is 2,500Wh/kg (the best li-ion batteries on the market are 200Wh/kg). Now, obviously, you can't discount everything but the sulfur. The sulfur:carbon:lithium ratio, by weight, works out to something like 7:3:2. So, excluding the electrolyte, separator, and casing (which should be small components on large-format prismatic cells), they should get about 950Wh/kg. I imagine in a large format cell, they could probably get 800-850 -- over 4x the best current li-ion. Also, it's quite convenient that all of the raw materials are cheap and have low toxicities.
Parent
Re:Question (Score:5, Funny)
Mods must be having a bad day, or just not reading TFA. Oh yeah, this is SlashDot. Par for the course.
Parent
Re: (Score:3, Insightful)
What do you expect, with all the new users that came over from 4chan now getting into to "eligible for moderation" zone?
Just look at the amount of 4chan memes that pop up around here.
Re: (Score:3, Informative)
Yes, it would be extremely dangerous to use this near any source of ignition. At least, that is unless you had some kind of highly complex extraction [bizfriendmarketing.com] device [toolstation.com] to remove the oxygen build up.
Sigh. I had this serious reply written up explaining how you had it backwards - it removes the oxygen from the air etc etc ...
Then I clicked the links. Good thing, I would've earned a "whoosh" otherwise...
Re:Question (Score:5, Funny)
Who knows, but it certainly gives new meaning to vaporware.
Parent
Re:Question (Score:5, Insightful)
According to the article the lithium is oxidized to Li2O2, so 1 mole of lithium takes half a mole of molecular oxygen during discharge. If the battery contains 100g of lithium (a large laptop battery might contain this amount), a total discharge would need
100 g / 6.941 g/mol * 0.5 * 22.4 dm3/mol * (100%/20%) = 806.8 l
of air, or less that one cubic metre. The second figure is the atomic mass of lithium, the third is the ratio of the stoichiometric coefficients of oxygen and lithium in thhe reaction, the fourth is the molar volume of ideal gas, and the last is the factor from oxygen concentration.
So unless you are in a coffin this is not a risk.
Parent
Re:Question (Score:5, Informative)
Addendum: the same amount of oxygen would be liberated when charging. It could be a problem if you decided to charge it in an air-tight box, but under normal conditions it won't be a problem.
Parent
Re: (Score:3, Informative)
They consume carbon dioxide and release oxygen.
CO2 + 2 H2O + energy becomes CH2O + H2O + O2
Powered by Air? (Score:5, Funny)
Re:Powered by Air? (Score:5, Insightful)
Nice headline Taco.
This is "fueled by air" in the same way an internal combustion engine is.
This is a Lithium battery. Why isn't Lithium in TFS?
Parent
Re: (Score:3, Insightful)
This is much more than an ordinary lithium battery, and the headline is quite appropriate. Internal combustion engines are in a very real sense "fueled by air", as are our own bodies, and using the same principle to extend the life of batteries without increasing weight or volume is a very good idea. It's not totally unprecedented, either, as zinc-air batteries do this; the innovation is making them rechargeable.
Re:Powered by Air? (Score:5, Informative)
Agreed. It's not even the first battery powered by air in this manner. As Taco ever heard of zinc-air batteries [wikipedia.org]? These are commonly used in, among other things, hearing aids.
Parent
Re: (Score:3, Informative)
You're trying to be funny.
The Carbon's there only to help hold the catalyst in place along with allowing oxygen from the air into the system to react.
Li-Ion batteries are fueled by oxides (Lithium Cobalt Oxide...) in the battery. If I'm understanding this correct, the battery consumes ambient oxygen while it's discharging and produces it when it's being recharged.
So it is Carbon neutral as it doesn't put CO2 into the environment.
Re:Powered by Air? (Score:5, Funny)
Parent
Re:Powered by Air? (Score:4, Informative)
Well, it's a lithium battery, that also includes an in-situ carbon fuel cell to replenish itself.
No, it is not. The carbon is only an adsorbent/catalyst matrix. Otherwise it would not be rechargeable. The first article contains misleading wording. Read the second one, or this one: http://www.theregister.co.uk/2009/05/19/lithium_oxygen_stair_battery/ [theregister.co.uk]
Parent
Re:Powered by Air? (Score:5, Funny)
Thank you, thank you... Try the duck, the veal is off tonight.
Parent
Any side-effects or drawbacks? (Score:5, Interesting)
Sometimes things sound too good to be true. Risk-free money smuggling from Nigeria. Enormous genitals from a few pills. Whiter teeth using only household chemicals. Articulate and clean presidential candidate who seems like he can fix anything.
Extending the life of batteries using the air sounds like a great thing. But what is the hidden problem that we are overlooking here? Will the chemical reaction of the battery and oxygen deplete the batteries faster than standard LIon? Are the batteries heavier? Output less power? Require usage patterns that aren't typical for normal users?
It just sounds too good to be true.
Re: (Score:3, Interesting)
Re: (Score:3, Insightful)
Not necessarily -- the carbon could act as a catalyst or component that is cycled throughout the charge-discharge process.
Re:Any side-effects or drawbacks? (Score:5, Informative)
Parent
Re: (Score:3, Informative)
Presumably the oxygen is going to released again when you recharge the battery. That's what recharging is, reversing the chemical reactions that took place during the discharge.
Re: (Score:3, Informative)
IANAC (chemist), but it sounds like what they are doing is take a reagent for the electrical reaction from the surrounding environment so they don't have to store it on board the battery -- thus freeing up additional weight/volume for the "charge" itself.
This might imply a problem with scale since you would need the infrastructure within the battery for safely extracting the reagent and, upon a recharge cycle, releasing it.
I wouldn't be surprised to see something like "DO NOT RECHARGE NEAR AN OPEN FLAME" wr
Re:Any side-effects or drawbacks? (Score:5, Insightful)
Those are the potential problems I can see:
1. The batteries will degrade over time, because the porous carbon used as the catalyst will slowly oxidize away.
2. Moisture sensitivity might be a problem. Graphite-lithium intercalate used in the negative electrode is, as far as I know, not resistant to water. Li2O2 also doesn't look stable (Na2O2, a close analogue, decomposes when subjected to moisture)
3. Total life might be additionally shortened in cities with smog. Smog contains highly oxidative species like nitrogen oxides and free radicals, which would accelerate the degradation of the carbon catalyst.
4. Obviously it won't be suitable for waterproof equipment.
5. Maximum power output might decrease with altitude (lower oxygen partial pressure).
The main problem is that you can't control the quality of air around the device, so I predict that preventing the battery from degrading when the air is not 100% clean and moisture free is going to be a challenge.
Parent
Wow. (Score:3, Interesting)
Re:Wow. (Score:5, Insightful)
This might be an exception (hopefully), but until you can get one off NewEgg people stay cool and cautious.
Parent
Is it rechargable? (Score:5, Interesting)
We have zinc-air elements for decades now, but they are not rechargeable.
Re: (Score:3, Interesting)
The second link in the article says yes, it is rechargeable.
Re:Is it rechargable? (Score:4, Informative)
Well, given the summary (and the article it plagiarizes from) explicitly says:
Okay, sure, that's a little vague. 'course, if one were to actually go through the trouble of RTFA, you'd see this quote from the second article:
So, I would guess that, yes, it's rechargeable.
Parent
Re: (Score:3, Insightful)
These elements, according to the coverage at The Register, are lithium-oxygen. The porous carbon storage matrix is just that, and plays more a mechanical role than a chemical one. I do so wish /. stories would link to articles that report science with at least the simplest facts right.
Re:Is it rechargable? (Score:5, Informative)
Rechargeable zinc-air battery, 4 years ago:
http://www.eetimes.com/news/semi/showArticle.jhtml?articleID=164903727 [eetimes.com]
I wonder whether they managed to take it anywhere. rechargeable zinc-air would be cool, because there's much more zinc than lithium on Earth.
Parent
Almost there (Score:5, Funny)
Re:Almost there (Score:5, Funny)
You are in luck [wikipedia.org].
(I love having to wait five minutes between posts)
Parent
Hearing aids and Zinc-air batteries (Score:5, Interesting)
Questions (Score:3, Interesting)
1) Energy density - including ventilation
2) Physical expansion during charge/discharge.
3) Degradation with each cycle - i.e. how many recharges before capacity is reduced xx%.
4) Performance over temperature range (-20C to say 60C)
5) Durability of the material.
The list goes on and on. It sounds like a nice lab experiment at this time.
Re: (Score:3, Informative)
So yeah, a lab experiment is all it really is at this point.
What's the output? (Score:3, Interesting)
If it's sucking in O2, what's the output?
Considering there's carbon in there my guess will be something along the lines of CO2 or CO.
Will this be better than burning fuel?
Then again, maybe it's not meant to be an environmental friendly solution, but more of an awesome-battery solution.
Re:What's the output? (Score:5, Informative)
Ok, second time I've had to do this; but, clearly the articles are pooorly written and do not describe the technology well, if at all.
It's a lithium-air battery in a carbon matrix. One electrode is lithium metal, one electrode is carbon. The oxygen, supplied by air and entering through the porous carbon electrode, reacts with the lithium to create lithium oxide. When the battery is recharged, the oxygen is liberated, returned to the atmosphere, and the lithium ions are returned to (plated on) the lithium metal electrode.
No CO2.
The output is electricity during discharge and oxygen during charging.
Parent
billions of years ago (Score:5, Funny)
for billions of years, for billions of generations, strange archaic anaerobacteria and primitive algae slaved their entire lives, heck, their entire species, to make your atmosphere one fifth oxygen
all so you could one day watch the family guy on hulu.com at a starbucks in pasadena
doesn't seem just
Re:billions of years ago (Score:5, Funny)
Slaved? Slaved? Oxygen is their poop!!! We're finally just recycling the damn stuff. And yes I think that watching Family Guy on Hulu at a Starbucks is a fine use for archaic anaerobacteria poop... it's strangely fitting in fact.
Parent
Lithium-oxygen, not carbon-oxygen (Score:4, Informative)
This coverage at The Register [theregister.co.uk] says they are lithium-oxygen batteries. The porous carbon matrix is for containing the chemicals and allowing the oxygen in during running and out during recharging.
smells like hot air (Score:3, Informative)
creates more energy
Two problems here:
1. you can't create energy
2. reacting oxygen with some carbon substance is called combustion and while it does indeed burn, it doesn't make a battery
Re: (Score:3, Informative)
Thankfully, the Telegraph and Slashdot both being what they are, it's not a carbon-oxygen battery at all. It's lithium-oxygen with a porous carbon matrix storing the lithium but allowing the oxygen to flow into and out of the chamber.
The air flowing in is actually what causes the usable energy to be released, as it is released by the oxidation of the lithium. It is recharged in a cycle of de-oxidizing the lithium.
Not the first (Score:5, Interesting)
More informative article (Score:5, Informative)
There is next to no information in the first article... this one is much more informative:
http://www.theregister.co.uk/2009/05/19/lithium_oxygen_stair_battery/ [theregister.co.uk]
The concept (taking one of the reagents from air) is not new. There were zinc-air batteries for decades, and they are widely used. They have one of the highest energy densities of all types of commercially available batteries.
http://en.wikipedia.org/wiki/Zinc-air_battery [wikipedia.org]
Seems like four years ago somebody even figured out how to make them electrically rechargeable (before that, the usual method of recharge was to replace the zinc plates and remove oxide waste, which was facilitated by cell design).
http://www.eetimes.com/news/semi/showArticle.jhtml?articleID=164903727 [eetimes.com]
However, if those new batteries use carbon instead of zinc, they might have a higher theoretical upper bound on energy density. It looks like they're using graphite-lithium intercalate for the negative electrode (a standard thing), and the positive electrode is essentially a combined catalyst/adsorbent for Li2O2 which forms during electricity generation.
CnLi ---> Li+ + Cn + e
2Li+ + 2e + O2 --cat.-> Li2O2
Note that the first article is rather bogus: O2 does not "recharge" the battery, it is only a reagent.
I'm not familiar with the cost breakdown for the components of Li-ion batteries, but lithium seems like a major contributor, so this might not be much cheaper than the traditional Li-ion.
Re:Wake me in 2014 (Score:4, Funny)
Seems like every new thing is going to be commercially available in 5 years. Why can't we have the future now? Do I have to move to Japan?
No, you had to move to Japan 5 years ago :P
Parent