Nanotube capacitors.

Using nanotube structures, the LEES invention promises a significant increase on the storage capacity of existing commercial ultracapacitors by storing electrical fields at an atomic level. The new LEES ultracapacitors could replace the conventional battery in everything from the smallest MP3 players through to electric automobiles and beyond, yielding batteries with a lifetime equivalent to the product they power and recharging times inside a minute. Most significantly, they promise a much smaller and lighter “battery”, and will be an enabling technology for many new concepts such as electric bicycles with the “burst” peak power of a motorcycle, or electrical trams with the capacity of a train but without the infrastructure. In automotive terms, they raise the possibility of an integrated starter/generator and the capability of ultra-efficient regenerative braking systems.

So, what's the catch? Well, no obvious violations of physics, but unfortunately, the article doesn't describe a time frame for getting them from the lab into your iPod. It seems almost inevitable, though.

the article doesn't describe a time frame for getting them from the lab into your iPod.

The line "The work was presented at the recent 15th International Seminar on Double Layer Capacitors and Hybrid Energy Storage Devices and the LEES “batteries” could reach market within five years." isn't a time frame? Or just not relatable to real-world-usability?

It is--I just missed it.

I didn't see anything about energy density.

Is this a better laptop battery, or something that could make electric cars actually *gasp* practical--say, 400 miles on a battery the size of a fuel tank?

Either way... faster, please; nanostructures are going to change our world more than plastics did.

Only one thing-- if these ultracapacitors can release their energy as fast as they can apparently be charged (a few minutes?), I wouldn't want to be *anywhere* near one should it "let go". Ever see a multi-hundred micro-farad cap charged up to several hundred volts "let go"? It's like a small hand-grenade. Now scale that up by a factor of several thousand, at least.....

*shudder*

It seems these discoveries never make it to become products for some reason. They are either announced at the time the product is introduced or they never surface after the initial report. After 5 years, who pays attention? The only exception I've noted was when Omni magazine annouced Asparteme before it was a product.

What happened to the infinitely rechargeable plastic battery that was going to be made like a fruit rollup and change the world? How's that clear plastic disc the size of a quarter that holds a terabyte coming from that Israeli company? I guess I'd just like to see the world change in my lifetime... for the better. In some ways it has, but mostly it's been a disappointment. 2001 anyone?

Energy density

The article said the new technology would permit storage equal to those of chemical batteries.

It seems these discoveries never make it to become products for some reason.

The reason for this is that to make it to a product, a long series of hurdles have to be passed. Fail at one of them and the you're out. You see this a lot with material science -- miss on just one important property and the material is a lab curiosity, not an useful engineering material.

The announcements tend to be made when a new interesting property is found, but before many of the other hurdles have been passed. Remember high Tc superconductors?

New Ultra Capacitor Energy Density, 60Wh/kg.
Current Lithium Ion Batter Energy Density, 120Wh/kg.

The big improvement is in power density.
New Ultra Capacitor Power Density, 100kW/kg.
Best Battery Power Density, .1kW/kg.

Here's the link:
http://lees.mit.edu/lees/posters/RU13_signorelli.pdf

Ultracapacitors would be most useful in hybrid drivetrains rather than as the sole energy storage system in a vehicle. The high power density would be very helpful here. I suspect they'd also be useful in electromagnetic accelerators.

I recall seeing ultracapacitors being looked at for digital mobile communication systems, where you might have high instantaneous power demands, particularly for space-based systems. The capacitor would smooth over fluctuations with the baseload being supplied by conventional batteries.

Thanks for the density numbers, Robert, but can anyone tell me off the top of their head (i'm too busy/lazy right now to look it up) how much a nano-tube ultracapacitor weighs compared to a LiO battery? That is, how do the energy and power densities compare to current batteries volume-for-volume? I seem to recall that this was one of the barriers to other recent "flexible battery" technologies, in that their densities by volume were less than 1% of current chemical batteries.

John, I think you're thinking of polymer batteries, which have been slower in progress than expected.

Also, those energy and power densities pretty much give you the weight. A laptop battery made of the stuff would have only half the life of a li-ion battery of the same weight (not size, that's another potential issue). However, it sounds like it charges faster.

The big difference is in how fast it can discharge the energy--a thousand times faster. That power density is plenty big enough to power a fully electric car with a relatively small battery pack--for half an hour.

So, it doesn't look like this will lead to electric cars by itself (if you can't get 300 miles between fuelings and have plentiful fueling stations, it ain't gonna work in the general market). It will, however, play well with other technologies to improve their performance. Hybrids will love this--it gives them rapid accelleration with an even tinier engine, and the capacitor has more of a chance to recharge during hard stop-and-go traffic. Also, anything that requires a high discharge rate but doesn't have to run for long between recharges will benefit--think cordless tools and kitchen appliances. Things like phones are the other way around--low-output, long duration--and may be better off with DMFC or (when the tech gets there) polymer batteries.

Hmmm, Plasma Pulse Rifles anyone.

Or space-based lasers?

Hmmm, that's a thought, Rand. Sooner than that, I could see this used in airborne/shipborne solid state lasers. Space based still needs a way to generate power (nuc or big solar array) or you only get a couple of shots.

> Hmmm, that's a thought, Rand. Sooner than that, I could see this used in
> airborne/shipborne solid state lasers. Space based still needs a way to
> generate power (nuc or big solar array) or you only get a couple of shots.

Air/sea-based needs a way to generate power, also. Perhaps not much of a problem for a ship with a big nuclear reactor, but more of a problem for aircraft.

And for cars. The prophets of electric cars keep forgetting that, regardless of the storage system, the energy has to come from somewhere. That means either fossil fuels, which doesn't solve the carbon emission problem the environmentalists are shouting about, or nuclear power, which would solve the emission problem but environmentalists still hate.

This does underline the folly of futurist predictions that assume there will be no unexpected technological developments for decades to come. Now, who said the only way out of the energy problem was to build fuel cells using platinum mined from the Moon, regardless of the cost, using ELVs and Constellation capsules?

The new tech ultra capacitor may only have half the storage compared to lithium ion chemical batteries, but that is still a huge improvement over the older ultra capacitors.

And then, what are the recharge limitations of lithium ion batteries? How quickly do they degrade? At what point do they only have half of their efficiency then when brand new? And how well do lithium ion batteries perform when at non-ideal temperatures?

"A lithium-ion battery provides 300-500 discharge/charge cycles. The battery prefers a partial rather than a full discharge. Frequent full discharges should be avoided when possible. Instead, charge the battery more often or use a larger battery. There is no concern of memory when applying unscheduled charges."

"Aging of lithium-ion is an issue that is often ignored. A lithium-ion battery in use typically lasts between 2-3 years. The capacity loss manifests itself in increased internal resistance caused by oxidation. Eventually, the cell resistance reaches a point where the pack can no longer deliver the stored energy although the battery may still have ample charge. For this reason, an aged battery can be kept longer in applications that draw low current as opposed to a function that demands heavy loads. Increasing internal resistance with cycle life and age is typical for cobalt-based lithium-ion, a system that is used for cell phones, cameras and laptops because of high energy density. The lower energy dense manganese-based lithium-ion, also known as spinel, maintains the internal resistance through its life but loses capacity due to chemical decompositions. Spinel is primarily used for power tools."

Supposedly the ultra capacitors don't suffer from any of these defects. And that is why they may make an electric car practical.

Brad: Energy density is (so far) against any kind of all-electric car. And yes, an electric car still has to have the electricity generated somewhere else--which proponents often omit. Still, *if* batteries can be developed that provide range and performance, it's probably more efficient to generate the electricity in a plant than in a car. It's not a change-the-world tech, but could have some benefits.

Ed: The AF has been planning for a couple of years to take a VTOL JSF, yank the lift fan out, and replace it with a laser cannon. The lift fan drive shaft turns a generator which feeds into a capacitor which feeds into the laser cannon. You could do the same thing with a palletized self-contained turbine in a AC-130 or something.

We're not talking huge amounts of juice here. I've seen numbers like 100kw out at 10% efficiency as being enough to shoot down a plane (or burn through a truck, or probably even the engine deck of a tank). Assuming that's for shots that don't take more than 3-4 seconds of lasing (that's my guess only), we're talking max input of 1 megawatt for 4 seconds per shot... which is, if I'm doing the math right, 1.1 kwh. The stumbling block is making a solid state laser powerful enough and cooling it.

Big D.: note that the lasers they are talking about there would be ideal for a heat-exchanger rocket laser launcher. They'd be ganged incoherently with multiple independent directors. I don't see the need for a capacitor, though; these lasers are continuous wave, not pulsed.

Paul: Details? The only laser launcher that I know of uses pulses against an ablative or reflective lower surface, not continuous. UV lasers are also in Liftport's plan, and I do think that those are continuous (not sure about power or heat issues offhand).

Please note that at 10% efficiency (they're not even to that yet), you still have to deal with 90% heat. The AF is having to deal with lots of cooling issues without even thinking about continuous.

Hey, since nanotubes started this post, does anybody know if there are any laser applications for nanotubes? Can they be used to improve the efficiency of the lasing process in any way, like building the lasing chamber out of them? Are there any opportunities from the thermal and electrical conductivity (or, placed perpendicular, insulation) properties of nanotubes?

For that matter, is anybody working on studies of how nanotube-reinforced composites or polymers could change rocket construction? I would expect mass ratios to improve a bit, at the very least.

Big D. See:

http://www.niac.usra.edu/files/library/meetings/fellows/mar04/897Kare.pdf

Please note that at 10% efficiency (they're not even to that yet),

Actually, no, they're already well past that. Semiconductor diode lasers are around 50% efficient, I think, and diode-pumped fiber lasers convert this to a single beam at 75% demonstrated efficiency. If I vaguely recall correctly, the airborne fighter laser would be a diode-pumped fiber laser.

Googling on diode-pumped lasers reveals all sorts of interesting information.

There's a DARPA program to increase the efficiency of the pump diodes. The program, called SHEDS, has already resulted in laser diodes with efficiency of 73% (at 10 C). The diode makers are finding that this increased efficiency is very desirable, not because it reduces electrical demand, but because the reduction in heating greatly extends the life of the laser diodes. Each 20 C decrease in diode temperature increases the life by a factor of 3.

Optical conversion efficiencies above .75 have been achieved in the fibers. At .8, and with diode efficiency of .73, the overall efficiency would be 58%. Even with other losses, an efficiency of greater than 50% should be achievable.

A leading supplier of these lasers is IPG Photonics (which is unfortunately privately held). They are poised to take market share from makers of the older technology industrial laser makers. As an example of one of their products, here is a page on a line of single mode 1075 nm lasers with powers up to 1.5 kW and wall-plug efficiency in excess of 25%. This is COTS technology.

Laboratory demonstrations of diode-pumped single mode fiber lasers has gone from a few watts in 2001 to 2 kW today, and shows no sign of being at fundamental limits. Kare assumes a power not much beyond this.

This thread is probably too far down now, but why not...

I was rather impressed by IPG. Things have come a long way in the last couple of years. I'm not sure how much I buy the practicality of 1-ton payloads for major construction, but they would be enough for frequent, cheap cargo/fuel runs to LEO.

Has anybody run any numbers on using on-board lasers to efficiently heat (LH2?) reaction mass in a combustionless engine in space? How does this compare to VASIMR in thrust/ISP?

Has anybody run any numbers on using on-board lasers to efficiently heat (LH2?) reaction mass in a combustionless engine in space? How does this compare to VASIMR in thrust/ISP?

I doubt it could compete with RF or arc heating. A pulsed laser ablation system might make a good microthruster.