Posted on 02/22/2015 10:55:50 AM PST by Red Badger
Researchers at the University of California, Riverside's Bourns College of Engineering have developed a novel paper-like material for lithium-ion batteries. It has the potential to boost by several times the specific energy, or amount of energy that can be delivered per unit weight of the battery.
This paper-like material is composed of sponge-like silicon nanofibers more than 100 times thinner than human hair. It could be used in batteries for electric vehicles and personal electronics.
Scanning electron microscope images of (a) SiO2 nanofibers after drying, (b) SiO2 nanofibers under high magnification (c) silicon nanofibers after etching, and (d) silicon nanofibers under high magnification.
The findings were just published in a paper, "Towards Scalable Binderless Electrodes: Carbon Coated Silicon Nanofiber Paper via Mg Reduction of Electrospun SiO2 Nanofibers," in the journal Nature Scientific Reports. The authors were Mihri Ozkan, a professor of electrical and computer engineering, Cengiz S. Ozkan, a professor of mechanical engineering, and six of their graduate students: Zach Favors, Hamed Hosseini Bay, Zafer Mutlu, Kazi Ahmed, Robert Ionescu and Rachel Ye.
The nanofibers were produced using a technique known as electrospinning, whereby 20,000 to 40,000 volts are applied between a rotating drum and a nozzle, which emits a solution composed mainly of tetraethyl orthosilicate (TEOS), a chemical compound frequently used in the semiconductor industry. The nanofibers are then exposed to magnesium vapor to produce the sponge-like silicon fiber structure.
Conventionally produced lithium-ion battery anodes are made using copper foil coated with a mixture of graphite, a conductive additive, and a polymer binder. But, because the performance of graphite has been nearly tapped out, researchers are experimenting with other materials, such as silicon, which has a specific capacity, or electrical charge per unit weight of the battery, nearly 10 times higher than graphite.
(a) Schematic representation of the electrospinning process and subsequent reduction process. Digital photographs of (b) as-spun SiO2 nanofibers paper, (c) etched silicon nanofiber paper, and (d) carbon-coated silicon nanofiber paper as used in the lithium-ion half-cell configuration.
The problem with silicon is that is suffers from significant volume expansion, which can quickly degrade the battery. The silicon nanofiber structure created in the Ozkan's labs circumvents this issue and allows the battery to be cycled hundreds of times without significant degradation.
"Eliminating the need for metal current collectors and inactive polymer binders while switching to an energy dense material such as silicon will significantly boost the range capabilities of electric vehicles," Favors said.
This technology also solves a problem that has plagued free-standing, or binderless, electrodes for years: scalability. Free-standing materials grown using chemical vapor deposition, such as carbon nanotubes or silicon nanowires, can only be produced in very small quantities (micrograms). However, Favors was able to produce several grams of silicon nanofibers at a time even at the lab scale.
The researchers' future work involves implementing the silicon nanofibers into a pouch cell format lithium-ion battery, which is a larger scale battery format that can be used in EVs and portable electronics.
Explore further: Sand-based lithium ion batteries that outperform standard by three times
More information: "Towards Scalable Binderless Electrodes: Carbon Coated Silicon Nanofiber Paper via Mg Reduction of Electrospun SiO2 Nanofibers" Scientific Reports 5, Article number: 8246 DOI: 10.1038/srep08246
Journal reference: Scientific Reports
Provided by University of California - Riverside
Battery Ping!................
That is I would be able to hear you if these new batteries were available for my hearing aids.
Good Report!
Thanks for the post.
100 times thinner
+++
Ah ha! Negative space. Crafty..
But any resultant automobile equipped with this new technology will still ultimately run on coal, and have a larger overall negative environmental impact than a conventional gasoline engine. All of these ‘science’ articles have a greenie-weenie subtext.
Soon the hearing aid will be the battery!..............
Of course. The MSM is green with envy................
Negative or positive?.............
The issue I have with lithium-ion batteries, is not the energy density so much. The caution I have is that if you pack the amount of energy in a container equal to the amount you would have with hydrocarbon fuels, it would be the equivalent to storing both the fuel and the oxidizer in the same tank.
You essentially have a bomb... This doesn’t alleviate this problem, it makes it worse.
How much Toxic Waste is produced making this paper-like material ?
I’m convinced that nanotechnology will bring unseen breakthroughs in battery technology. And you’ll be able to see each and every one ridiculed by the science-class flunkouts right here on FR.
Alternating.
This sounds similar to some MIT research on “solid state” batteries. With electric vehicles in the 35 (Volt) to around 250 (Tesla) range at present, I hope we see a tripling. Not a greenie, but I do not believe West Texas Intermediate will be around $50 per barrel for more than a few years. And I like to drive.
We need to change the name from “ping” to “ZAP” list.
It is my strong opinion that Texas Intermediate Crude will go higher than $80/bbl (inflation adjusted) for NO LONGER than 4 months ever again in the next 100 years. The amount of shale gas&oil available in the USA will place severe limits on what the market will bear. The average monthly price will be at or under $65/bbl. Many economic and technological factors will contribute to this. OPEC is now dead as a long-term economic force though of course they can cause short term (major) pain and dislocations any time they wish.
That’s really an interesting take, and I hope it is true. I hear a repeated refrain that fracked oil wells peak and output diminishes quickly after 2 to 4 years. It made sense economically with oil above $110 per barrel, but not at half that. That’s what I hear from one side, and they claim to have the well-life data to back it up.
And Venezuela needs $110 per barrel oil for its government to stay afloat. Persistent costs below that rate and it is coup time. So I really hope you are right.
Viva la Revolucion!
Coal makes up less than 40% of our electricity generation nationwide. The other 60% comes from much cleaner sources like natural gas, nuclear, and hydro. Furthermore, in the states where most EVs are sold, the proportion that comes from coal is far less than 40%.
Only if you live in the heart of coal country is it worse to drive an electric car than a gasmobile.
Besides, we should prefer to drive on American-made electricity, regardless of the source, rather than remain dependent on oil which has so many geopolitical downsides. People forget that even as we have become the world's #1 oil producer, we still have to import 18% of our oil from OPEC.
For now, if the Chinese are successful with Thorium then perhaps we’ll have a way to safely retire coal, or use the much cheaper electricity to transform coal to diesel.
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