Nanowires Boost Laptop Battery Life to 20 Hours

brianmed writes to tell us that Stanford researchers have created a new use for silicon nanowires that promise to reinvent lithium-ion batteries. "The new version, developed through research led by Yi Cui, assistant professor of materials science and engineering, produces 10 times the amount of electricity of existing lithium-ion, known as Li-ion, batteries. A laptop that now runs on battery for two hours could operate for 20 hours, a boon to ocean-hopping business travelers. [...] The lithium is stored in a forest of tiny silicon nanowires, each with a diameter one-thousandth the thickness of a sheet of paper. The nanowires inflate four times their normal size as they soak up lithium. But, unlike other silicon shapes, they do not fracture."

Sony Nanowire Batteries

[Apple Acolyte (517892)]

Now with 10 times the explosive power.

Re:Sony Nanowire Batteries

[mpe (36238)]

Now with 10 times the explosive power.

How long before laptop batteries get classified as "munitions"?

Re:Sony Nanowire Batteries

[GospelHead821 (466923)]

It's sort of funny that you should say that. I work for a company that manufactures some battery-powered instruments. We actually have to ship the batteries separately from the instruments because they classify as a more hazardous material than the rest of the shipment.

Re:Sony Nanowire Batteries

[gweihir (88907)]

Actually energy contents is already higher than some explosives. The current limitation is that you cannot releaste the energy in a short burst.

I'm amped just reading this...

[Akardam (186995)]

The current limitation is that you cannot releaste the energy in a short burst.
Yes, precisely!

Re:Sony Nanowire Batteries

[Hal_Porter (817932)]

How does the power density of these compare to gasoline?

Lousy

http://wiki.xtronics.com/index.php/Energy_density [xtronics.com]

Material Volumetric(Wh/l)Gravimetric (Wh/kg)

Fission of U-235 4.7 x 1012 2.5 x1010
Boron 38,278 16361
JP10 (dicyclopentadiene)10,975 11,694
Diesel 10,942 13,762
Gasoline 9,700 12,200
Black Coal solid =>CO2 9444 6667
LNG 7,216 12,100
Propane (liquid) 7,500 - 6,600 13,900
Black Coal Bulk =>CO2 6278 6667
Ethanol 6,100 7,850
Methanol 4,600 6,400
Liquid H2 2,600 39,000
Secondary LiOn Polymer 300 130 - 1200
Secondary Lithium-Ion 300 110
Nickel Metal Hydride 100 Wh/l 60Wh/kg
Lead Acid Battery 40 25
Propane (Gas - 1 bar) 28.1 13,900
Compressed Air 17 34
Ice to water 9.3 9.3

If this new battery is 10x as efficient it is still 3x worse than gasoline.

Re:Sony Nanowire Batteries

[OwnedByTwoCats (124103)]

Gasoline 9,700 12,200

...
Secondary LiOn Polymer 300 130 - 1200

Do the rest of the math.

300 * 10 is 3000, so gasoline still stores three times as much potential chemical energy as the battery. But converting chemical potential energy into motion through an internal combustion engine is about 30% efficient, while power electronics and electric motors net between 80 and 95% efficient.

• Battery: 3000 * 0.8 = 2400
• Gasoline: 9,700 * 0.3 = 2910

so getting batteries to within 80% of gasoline (i.e. same volumetric energy density as a vehicle fuel as ethanol) really is revolutionary.

If these Li-Ion batteries are on the lighter end of the scale, the energy/weight figures could be extrordinary.

• Battery: 1200 * 10 (improvement from research) * 0.8 (efficiency) = 9600 watt-hours traction per kilogram
• Gasoline: 12200 * 0.3 (efficiency) = 3660 watt-hours traction per kilogram.

This is breakthrough territory.

Re:Sony Nanowire Batteries

[Rei (128717)]

Well, let's go with 200 Wh/kg for conventional li-ion batteries. Thios would be 2000 Wh/kg, i.e., 7.2 MJ/kg. Gasoline has an energy density of about 45 MJ/kg.

Of course, you're comparing the energy density of the stored electricity, not of the chemical energy of the battery as a whole, which isn't really fair.

Anyways, let's look at vehicle range. The gasoline has 6.25 times the energy density, but only burns at 25-30% efficiency in the engine. The charge/discharge of lithium-ion batteries is almost lossless. The motor would be 85-90% efficient. Looks like, kilogram per kilogram, gasoline gets twice the range. On the other hand, there are other practical considerations -- namely, the fact that electric motors are much smaller and lighter than an internal combustion engine. I wouldn't be surprised if you could shave a hundred, hundred fifty kilograms off the engine/motor mass by switching from ICE to electric. If you filled this remaining space with batteries, that'd be ~900MJ, the equivalent of 20 gallons of gasoline, extra for the electric vehicle. Factor in a 12 gallon gas tank that's being replaced by electric (that's what my Saturn has, so that's the number I'm using), that's the equivalent of 26 gallons of range for the electric and 12 gallons of range for the gasoline vehicle. The electric goes over twice as far. But it gets even better, as you'll only get your optimum 25-30% gasoline efficiency at the optimal RPM; they perform poorly at low speeds, for example. Electrics perform well over a wide range. Then you need to factor in that the electric has all of the benefits of hybrid vehicles already there -- regenerative braking, no waste at stop lights, and so forth. All in all, I'd expect around three times more range with an electric using batteries like these than you get in a gasoline vehicle. And to top it all off, given that they're using nanowires, the surface are will be incredible, so the charge time should be very fast -- just a few minutes.

If this is legit, and if there aren't any degradation or safety problems that sneak up on them, when it comes out, gasoline vehicles can be expected to go "extinct" quite quickly. Who *wouldn't* want to be able to drive a thousand, perhaps even two thousand miles on a single charge, at a price of 1-2 cents per mile?

Re:Sony Nanowire Batteries

[Rei (128717)]

. If you use your figure of 900MJ, and charging is 90% efficient

There's your problem right there. Li-ion batteries have a charge efficiency of around 99.9% [batteryuniversity.com]; you're two orders of magnitude off. Even if you go off by an order of magnitude and say 99% efficient, assuming a specific heat of 1J/g*C, with 7.2MJ/kg, that's only a 72 degree rise in temperature over 5 minutes or so (240W of heat), which a cooling system could easily manage (your computer case fan probably dissipates more heat than that). With the actual 99.9% efficiency, it's a 7.2 degree rise in temperature and 24W of heat, respectively.

The other issue is that we (US) have nowhere near the generation capacity to handle a nation full of electric cars.

Another widespread false concern. The fact is that the US has significant surplus generation capacity at night, more than enough to begin the transition (it's not like everyone collectively throws out their vehicles and switches at once). Furthermore, it's much *cheaper* to build new electricity production infrastructure than it is to produce gasoline production infrastructure. And, for gasoline-powered cars, you have to keep producing new gasoline-production infrastructure even when gasoline demand remains constant since oil fields run dry. You're just replacing one type of infrastructure demand with another -- one that's easier to meet to boot.

Re:Sony Nanowire Batteries

[arivanov (12034)]

No boom today. Boom tomorrow. There is always a boom tomorrow. http://www.youtube.com/watch?v=fEsFB2GPy24 [youtube.com]

Re:Sony Nanowire Batteries

[192939495969798999 (58312)]

Not only that, but when it explodes in your lap, you get riddled with nanowire superpowers! And mostly in the very area that your laptop's radiation has probably been eroding your powers.

Re:A bit like shrapnel.

[Pope (17780)]

Are you joking? Batteries have come a LONG way since WW 2! Granted, electronics have become more powerful and energy-efficient as well, but you can't deny the progress made. Look at the life of a current generation set of Lithium AAs.

Smaller lighter batteries

[farnsaw (252018)]

Rather than tripling the life of a current battery, I can see this being used to power a laptop off a battery the size of a current cell phone battery and shrinking cell phone batteries to the size of a nickel. This will drastically reduce the size of several of our common devices such as Bluetooth headsets, cell phones, iPods (and other MP3 players), digital cameras, etc. In many such devices, the battery is still the single largest and heaviest component and being able to shrink this by a factor of 3-5 will drastically affect the size and weight of them.

Re:Smaller lighter batteries

[Xentor (600436)]

Careful, or he'll give ya the 132 salute.

4277mA hours per gram

[TopSpin (753)]

A short but more technical story found here [rsc.org].

Any work on the flip side?

[iamacat (583406)]

It's a shame that enough power to cause a massive explosion can only power a device that, for the most part, just displays text for 3 hours. We really need to rethink what a computer does when someone reads e-mail or browses the web. With an e-paper display, processor, disk and a WiFi radio should just briefly power themselves on when the user goes to a new URL and then completely shut down, yielding weeks of typical use on a single charge. Audio and video playback can be achieved by a dedicated chip and achieve playback times of the latest iPods. If users also want to use the same laptop as a desktop replacement, it can an internal PDA-like subsystem with it's own low power CPU, RAM and flash storage that synchronizes some directories with the main disk. Users can then choose weather they need high performance or long battery life at the moment and control either subsystem from the same display, keyboard and trackpad.

With clever engineering it should be possible to make a laptop exclusively used in low power mode solar powered if it's normally left out when not in use.

Critical questions of how

[Sitnalta (1051230)]

1) How much will they cost
2) How long does it take to charge
3) How many charges can you get in its lifetime.

If any one of those is a major deficiency, the technology will be worthless. Since they didn't immediately bring up use in electric cars, I'm guessing there's currently a fatal flaw that applies to one of those questions.

My money is still on ultra-capacitors.

Re:Critical questions of how

[quickpick (1021471)]

1) How much will they cost
If you have to ask you can't afford it.
2) How long does it take to charge
Not too long, plug it in and wait for the amber light to turn green.
3) How many charges can you get in its lifetime.
If its made by Apple you can charge it as many times as you want, but replacing it will cost about 82% of the original cost of the full price of the original device you bought it for UNLESS you buy an Apple Care Plan for 73% of the full price of the original device you bought it for.

If any one of those is a major deficiency, the technology will be worthless. Since they didn't immediately bring up use in electric cars, I'm guessing there's currently a fatal flaw that applies to one of those questions. They will ALL be deficient to one person or another...therefore the technology will be worthless in some aspect by someone. Why is it that people only want to use it in electric cars? I'm sure all the single and lonely women wouldn't mind having a device that doesn't quit on them before they're TRULY satisfied...which will never happen because women are never satisfied. Thats why its called a ball and chain.

My money is still on ultra-capacitors.
You fool. My money is in Gold because the Fiat System will fail at some point and you can't buy food with ultra-capacitors...

Re:Promising

[explosivejared (1186049)]

I'll say it sounds promising. A major hindrance to using alternative energy (eg solar), which is what most want to move to, to produce electricity is storing the power. The sun and wind, among other things, can't exactly be controlled manually to produce power on a whim. Inefficient storing is a major drawback. Any advance that improves storage capacity (for any platform) by an order of magnitude is promising to say the least. The article barely touched on how important this could be.

Re:Promising

[TheRaven64 (641858)]

It's not exactly a memory effect, but LiIon batteries do degrade over time. Unlike NiCd cells, their life is best preserved by keeping them about around 50% charge. You get a lot of people complaining that their batteries wear out quickly because they still think the things they learned about NiCd cells apply, so they fully discharge and recharge their LiIon cells, which is the absolute worst case for them.

Re:would this be a deserving patent

[MightyYar (622222)]

I'd say that increasing battery performance by 10x is EXACTLY the kind of thing that the patent system is built for. This development can only be good for society, even if we have to wait a few years before it becomes generic.

Re:Thickness of paper?

[1000101 (584896)]

Stack up 4,648,421,052 of these bad boys and you'll have a nano wire Empire State building. Conversely, the length of these are approximately 2.15x10^-7 Empire State Building's long*.

*including tower

Wrong.

[TheMeuge (645043)]

obviously, you're unaware of the natural leakage of rechargeable batteries. even in the "off" position, most rechargeable batteries will discharge in a matter of weeks on the upper end.

That's highly incorrect. Lithium ion batteries have a self-discharge rate of about 5% per month. However, while the battery is connected to a power supply, some energy is always consumed, just like the way desktop PSUs consume power when the computer is off, but when the PSU cutoff switch is not switched off. That's why laptops will not stay charged for months when unused. Take the battery OUT of the laptop, and you will be able to power it on a year after you turn it off.

Low-self-discharge (LSD) NiMH cells (such as Sanyo Eneloop) have discharge rates that are even lower... up to as little as 20% per year.

Re:patent

[Dahamma (304068)]

Universities have patent licensing programs for this, and often support their facultry or students in founding companies based on their research.

I'm sure Stanford has made a killing by licensing to or investing in companies. Here's a list of their startup investments - not necessarily patent related, but I'm sure many were founded by Stanford professors or alumni with patents licensed back from the university...

http://otl.stanford.edu/about/resources/equity.html [stanford.edu]

They probably made over a billion on Google alone...

Because of the Bayh-Dole act

[Animats (122034)]

Because of the Bayh-Dole Act [wikipedia.org], which commercialized federally-funded research.