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Lithium Air Batteries Get Boost From IBM and DOE
coondoggie writes "The Department of Energy and IBM are serious about developing controversial lithium air batteries capable of powering a car for 500 miles on a single charge – a huge increase over current plug-in batteries that have a range of about 40 to 100 miles, the DOE said. The agency said 24 million hours of supercomputing time out of a total of 1.6 billion available hours at Argonne and Oak Ridge National Laboratories will be used by IBM and a team of researchers from those labs and Vanderbilt University to design new materials required for a lithium air battery."
Current plug-in vehicles? Like, what a Chevy Volt or a hacked Prius? Nonsense. Try a Tesla Roadster, with a single charge range of 250 miles. Lithium-air might double the range then. But a factor of 5? No.
I do have one question though. How are lithium-ion batteries affected by increasing cell size? The Tesla Roadster currently uses a ridiculous number of very small cells in its pack, in a move that looks dictated by ridiculous patent licensing terms limiting cell sizes to those suitable for laptops in an effort to prevent the existence of something like the Roadster. That's what it looks like. But is there a technical reason to limit cell size? There is surprisingly little information available about how the performance of lithium cells change as they get physically larger (or smaller).
Lithium-air is, IMHO, one of the least promising upcoming battery techs. It's really more like a fuel cell, and to be blunt, fuel cells suck. By that, I mean:
* Expensive per watt
* Short lifespans
* Inefficient
There are many, many promising next-gen battery techs other than li-air. Here's just a couple of my favorites.
Lithium-sulfur: This has long been worked on, but only just recently one of its big problems has been worked around. It offers great energy density, but some of the intermediary reaction products -- various lithium polysulfides -- are rather soluble. They'd migrate across the membrane and precipitate out on the other side, being rendered permanently useless to the reaction and thus aging the cells very quickly. Older solutions to try to prevent this caused dramatically lower energy density. The latest technique involves wicking the sulfur into the pores of mesoporous carbon and then functionalizing the outside of the carbon with polyethylene glycol to keep the hydrophobic polysulfides inside when they form. The longevity improvements were amazing, without sacrificing energy density. We're talking that when they deliberately chose a worst-case solvent, one that's really good at dissolving polysulfides, the traditional Li-S cell lost 96% of its sulfur in 30 cycles while theirs only lost 25%.
Nickel-lithium: It is, quite literally, a hybrid NiMH/li-ion battery -- a traditional NiMH cathode that can hold a tremendous amount of lithium, and a lithium metal anode (almost obscene anode energy density). That's normally impossible, since you want to run a NiMH battery with an aqueous electrolyte and your various lithium-based cells with an organic electrolyte. They do both -- they use a new tech called a LISICON membrane to keep the two different electrolytes apart but allow lithium ions across. An additional problem with li metal anodes is that dendrites tend to form that rupture the membrane -- but LISICON membranes are a rigid ceramic that resists dendrite damage.
Digital quantum battery: This is my favorite, because it comes straight out of left field. It's really a type of capacitor. Now, capacitors normally hold a lot less energy than batteries; if the voltage gets too high, you get dielectric breakdown, it arcs across, and your energy is lost. But at very tiny scales, current must move as quanta. So if instead of a single big capacitor, you lithographically print an array of nanoscale capacitors, all of the sudden you can make it so that you essentially can't get dielectric breakdown. In fact, you can store so much energy that the stresses become so great that it's best to use a carbon nanotube for one of the electrodes in each nano-capacitor. :)
And even ignoring next-gen battery techs, there is still *huge* range for improvement in li-ion. In particular, for the cathodes, my favorites are layered manganese cathodes which alternate long-life forms and high energy density forms of magnanese oxides to get both properties; and fluorinated metal cathodes. For the anodes, there's many kinds of tin and particularly silicon anodes out there that store nearly an order of magnitude more lithium than conventional graphite anodes. Silicon anode li-ion cells are just this month starting to hit the market. The tech has finally matured to the point where their longevity is sufficient.
Noone ever goes walrus!
But how are you going to distribute the power? My house gets 100A at 250V so thats 25000 watts. I doubt the cable in the street can supply that to each house at the same time (car charging time) when the electric stoves are cooking dinner as well. For 100kw we need four times that so at best we need to double the diameter of every cable running along every street and push back higher peak current requirements into the distribution system as well.
I think we are going to need to charge more for high current delivery on top of high energy delivery to encourage slow overnight charging, otherwise the networks and generators won't be able to cope with the demand.
http://michaelsmith.id.au
Not even close. For example, beryllium blows it away in both volumetric and gravimetric energy density (and hydrogen blows beryllium out of the water in gravimetric comparisons, but sucks at volumetric).
Hydrogen was included in TFA comparison.
No, it isn't. Nor is beryllium. Energy doesn't even have to be stored in chemical bonds (see, for example, digital quantum batteries).
Energy is still stored in the electrical field in matter. A quantum battery needs a lot of infrastructure to handle the forces, so at least 50% of the weight will be wasted. (compare to the weight of a clamp holding a spring.)
Try 4x in typical driving conditions.
No, A small VW diesel has up to 40% efficiency. An elelctric car may have 90%, but you can only use 60% of the battery without damaging it in a few cycles, so overall, 2x is conservative.
It doesn't need to. A motor the size of a watermelon propels the Tesla Roadster from 0-60 in under 4 seconds. In gasoline cars, the fuel is light and the engine is heavy. In EVs, the motor is light and the "fuel" (the battery pack) is heavy. It's a reversed paradigm. You have to compare the mass and volume of the engine + fuel to the mass and volume of motor + fuel. And with current battery tech, you'll find that EVs are about 1/4 to 1/3 of the way to matching gasoline cars. But batteries have increased nearly 5-fold in energy density the past 21 years, and show no signs of stopping.
You are partially correct. A brushless electric motor can have very high intermittent power density. maybe 10x of a gas engine. It is only limited by cooling. For continous power its power density is the same as a gas engine. Maybe a hybrid combination can beat either. It is actually quite complicated to cool an electric motor. Think 100kW power, and 10kW heat. That means liquid cooling with pumps. radiators, and a much bigger motor to accommodate water cooling. Find an electric motor that had higher energy density than a gas engine for continous output, and I will stand corrected, and learn something new.
Here is a 220kg gas engine rated for 200kW continuous and 330kW peak: http://en.wikipedia.org/wiki/Porsche_993#Turbo_S
don't cut it off www.mgmbill.org