Nanowires Boost Laptop Battery Life to 20 Hours 238
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."
4277mA hours per gram (Score:5, Informative)
Re:Promising (Score:5, Informative)
Wrong. (Score:4, Informative)
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:Promising (Score:3, Informative)
Re:patent (Score:5, Informative)
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 (Score:5, Informative)
Because of the Bayh-Dole Act [wikipedia.org], which commercialized federally-funded research.
Re:Any work on the flip side? (Score:4, Informative)
You mean like this one? [laptop.org]
Re:Promising (Score:3, Informative)
Wow, you have no familiarity with the concept of long-term investments do you? No, solar isn't an economical investment in most places. But if you expect your investments to return your expenditures in one year, I'd hate to see what your retirement plan looks like.
For anyone interested in seeing how the economics of solar power works out where they live, check out this handy-dandy photovoltaics economics calculator [daughtersoftiresias.org].
Re:Sony Nanowire Batteries (Score:5, Informative)
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:Promising (Score:3, Informative)
Re:Recharge Cycles (Score:3, Informative)
Re:patent (Score:3, Informative)
"The Employee hereby assigns and transfers to the Company without further consideration his entire right, title and interest in and to all Inventions developed while in the employ of the Company."
Sign on the dotted line or you're not hired! The article mentions the professor may start a company to exploit his discovery. To do so, he will have to license the technology from Stanford, even though the patent is in his name!
Re:Sony Nanowire Batteries (Score:2, Informative)
Dividing by 3600J gives 5 * 10^13 Wh/kilogram
http://www.google.com/search?hl=en&q=(2kg+*+(c%5E2)%2F++3%2C600&btnG=Search [google.com]
Re:Sony Nanowire Batteries (Score:5, Informative)
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:On that note... (Score:3, Informative)