Battery binder: This microscopy image shows a silicon electrode before charging (left) and after 32 cycles. A new binder keeps the particles close together. Lawrence Berkeley National Laboratory
Posted on 09/30/2011 8:51:17 AM PDT by Red Badger
A stretchy binder material that's compatible with existing factories could help electric cars and portable electronics go 30 percent longer.
A stretchy binder material that's compatible with existing factories could help electric cars and portable electronics go 30 percent longer.
One approach to the problem is to structure these anodes in a totally different way, for example growing shaggy arrays of silicon nanowires that can bend, swell, and move around as lithium enters and exits. This approach is being commercialized by Amprius, a startup in Palo Alto, California. But growing nanowires requires new processes that aren't normally used in battery manufacturing.
Today's anodes are made by painting a solvent-based slurry of graphite particles held together with a binder, a simple process that keeps costs low. The Berkeley researchers believe the key to making new battery materials like silicon work is to stick with this manufacturing process. That meant coming up with a rubbery binder that would stick to silicon particles, remain highly conductive in the harsh environment of the anode, and stretch and contract as the anode swells and deflates.
Battery binder: This microscopy image shows a silicon electrode before charging (left) and after 32 cycles. A new binder keeps the particles close together. Lawrence Berkeley National Laboratory
THE REST OF THE ARTICLE:
Most work on advanced batteries has focused on the active materials, but “we have pushed these materials to the limit,” says Yury Gogotsi, professor of materials science and engineering at Drexel University. “Now what’s limiting us are the binders.”
Reading through papers on silicon battery binders, Liu noticed that researchers were making “fatal mistakes”—choosing polymers that lose their conductivity in the kinds of conditions found in an anode, for example. He worked with theoretical chemists to come up with a list of polymers with the right electrical properties for the job. Once they found one, they altered it to make it much stickier. Once they developed and characterized this new material, they were able to make silicon anodes using conventional processes, and test them in batteries.
The Berkeley group’s anodes have been tested in over 650 charging cycles. They maintain a storage capacity of 1,400 milliamp hours per gram—much greater than the 300 or so stored by conventional anodes. Full batteries incorporating the anodes store about 30 percent more total energy than a commercial lithium-ion battery. Typically, battery capacity increases by about 5 percent a year, Liu notes. He says they’ve tested the binder in other battery anodes, including those made of tin, that have similar potential and problems, and that it should work for any such materials.
The storage capacity of these batteries is nearly as good as those made from pure silicon nanowires with no binders, says Yi Cui, professor of materials science and engineering at Stanford and one of the founders of Amprius. That’s impressive, he says, considering that the binder doesn’t store any lithium.
Liu’s group is now collaborating with researchers at 3M on the anode research. 3M is scaling up production of silicon-based battery materials designed to not expand quite so much during charging, says Kevin Eberman, who is developing battery materials products at 3M Electronics in St. Paul, Minnesota. But to make them work, a good binder is key. The company is providing the Berkeley group with materials to test. Liu says the Berkeley group has patented the binders, and is in talks with a few companies about ways to commercialize them.
Incremental advances are always welcome, but are not the breakthrough necessary to make electric cars practical.
FINALLY!
A use for all those shaggy arrays of silicon nano-wires growing in the back of my refrigerator...
...
...
...
No...
Wait...
I think that might be mold...
Well, now, instead of 40 miles on a charge, you can go 52 miles.......;^)
“Opportunities multiply as they are seized” - Sun Tzu
Incremental advances lead to break throughs.
The electric car will never be practical other than in niche applications. Regardless of that, the huge push in battery technology has broad benefits.
So I can go 170 miles instead of 150 miles?
“Well, now, instead of 40 miles on a charge, you can go 52 miles.......;^)”
If the car is as cheap as a gas vehicle to buy, that makes it viable to get me to work and back (36 miles in New Hampshire) and probably run the heater too.
WOW instead of going 50 miles between charges they will be able to go 65 miles. Makes all the difference.
So what? You still have to burn the BTUs to charge it.
I’m more excited by what this means for my mobile phone, laptop and tablet!!!!!
Who cares about electric cars?!
So what? You still have to burn the BTUs to charge it.
Power companies generate electricity/power more efficiently than running a gasoline powered car.
He was being sarcastic but I’ve got to say, there is a huge difference between burning domestic coal or gas BTU’s and burning BTU’s imported from some third world dictator.
Disclaimer: Opinions posted on Free Republic are those of the individual posters and do not necessarily represent the opinion of Free Republic or its management. All materials posted herein are protected by copyright law and the exemption for fair use of copyrighted works.