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Lengthening the life of high capacity silicon electrodes in rechargeable lithium batteries
(Please note US Federal Laboratory Press Release. Copyright concerns are nil.)
http://www.pnnl.gov/news/release.aspx?id=3169
[font face=Serif][font size=5]Lengthening the life of high capacity silicon electrodes in rechargeable lithium batteries[/font]
[font size=4]Novel rubber-like coating could lead to longer lasting batteries[/font]
December 02, 2014
Mary Beckman, PNNL, (509) 375-3688
[font size=3]RICHLAND, Wash. – A new study will help researchers create longer-lasting, higher-capacity lithium rechargeable batteries, which are commonly used in consumer electronics. In a study published in the journal ACS Nano, researchers showed how a coating that makes high capacity silicon electrodes more durable could lead to a replacement for lower-capacity graphite electrodes.
"Understanding how the coating works gives us an indication of the direction we need to move in to overcome the problems with silicon electrodes," said materials scientist Chongmin Wang of the Department of Energy's Pacific Northwest National Laboratory.
Thanks to its high electrical capacity potential, silicon is one of the hottest things in lithium ion battery development these days. Replacing the graphite electrode in rechargeable lithium batteries with silicon could increase the capacity ten-fold, making them last many hours longer before they run out of juice. The problem? Silicon electrodes aren't very durable — after a few dozen recharges, they can no longer hold electricity.
That's partly due to how silicon takes up lithium — like a sponge. When charging, lithium infiltrates the silicon electrode. The lithium causes the silicon electrode to swell up to three times its original size. Possibly as a result of the swelling or for other unknown reasons, the silicon fractures and breaks down.
Researchers have been using electrodes made up of tiny silicon spheres about 150 nanometers wide — about a thousand times smaller than a human hair — to overcome some of the limitations of silicon as an electrode. The small size lets silicon charge quickly and thoroughly — an improvement over earlier silicon electrodes — but only partly alleviates the fracturing problem.
Last year, materials scientist Chunmei Ban and her colleagues at the National Renewable Energy Laboratory in Golden, Colorado, and the University of Colorado, Boulder found that they could cover silicon nanoparticles with a rubber-like coating made from aluminum glycerol. The coated silicon particles lasted at least five times longer — uncoated particles died by 30 cycles, but the coated ones still carried a charge after 150 cycles.
...[/font][/font]
http://dx.doi.org/10.1021/nn505523c[font size=4]Novel rubber-like coating could lead to longer lasting batteries[/font]
December 02, 2014
Mary Beckman, PNNL, (509) 375-3688
[font size=3]RICHLAND, Wash. – A new study will help researchers create longer-lasting, higher-capacity lithium rechargeable batteries, which are commonly used in consumer electronics. In a study published in the journal ACS Nano, researchers showed how a coating that makes high capacity silicon electrodes more durable could lead to a replacement for lower-capacity graphite electrodes.
"Understanding how the coating works gives us an indication of the direction we need to move in to overcome the problems with silicon electrodes," said materials scientist Chongmin Wang of the Department of Energy's Pacific Northwest National Laboratory.
Thanks to its high electrical capacity potential, silicon is one of the hottest things in lithium ion battery development these days. Replacing the graphite electrode in rechargeable lithium batteries with silicon could increase the capacity ten-fold, making them last many hours longer before they run out of juice. The problem? Silicon electrodes aren't very durable — after a few dozen recharges, they can no longer hold electricity.
That's partly due to how silicon takes up lithium — like a sponge. When charging, lithium infiltrates the silicon electrode. The lithium causes the silicon electrode to swell up to three times its original size. Possibly as a result of the swelling or for other unknown reasons, the silicon fractures and breaks down.
Researchers have been using electrodes made up of tiny silicon spheres about 150 nanometers wide — about a thousand times smaller than a human hair — to overcome some of the limitations of silicon as an electrode. The small size lets silicon charge quickly and thoroughly — an improvement over earlier silicon electrodes — but only partly alleviates the fracturing problem.
Last year, materials scientist Chunmei Ban and her colleagues at the National Renewable Energy Laboratory in Golden, Colorado, and the University of Colorado, Boulder found that they could cover silicon nanoparticles with a rubber-like coating made from aluminum glycerol. The coated silicon particles lasted at least five times longer — uncoated particles died by 30 cycles, but the coated ones still carried a charge after 150 cycles.
...[/font][/font]