That’s been going on for more than 10 years, scientists are trying to improve lithium-based battery, replacing the graphite is one of the terminals on the silicon, allowing you to store 10 times more energy. But the problem was that after a few charge / discharge cycles, the silicon structure begins to crack and crumble, and the battery is destroyed.
The team, led by Yi Kyuy material science from Stanford, was able to find a solution: cleverly designed double-walled nanostructure allows the new battery to maintain their properties for more than 6000 cycles, which far exceeds the needs of the industry electric cars and mobile electronics. When charging times daily life is 16 years.
"This is a very positive development on the way to our goal, which is to create a more compact, lightweight and long-lasting batteries," - said Kyuy. The results were published in the journal Nature Nanotechnology.
Lithium-ion batteries are widely used as power source for portable electric and electronics, stored as a relatively large amount of energy and relatively compact. Operation of the battery based on the overflow of the lithium ions through the liquid electrolyte between the two terminals called an anode and a cathode.
Scientists have long been trying to create a battery in which the anode is made of silicon. The advantage of this solution is how the lithium ions are bound to the silicon during charging. Up to 4 lithium ions attached to the silicon atom of each anode - for comparison, only one lithium atom binds to six carbon atoms as used today graphite anode. This is due to an increase in battery capacity.
However, this leads to an increase of the anode to four times its original volume. Moreover, some electrolyte react with silicon, covering it and giving produce charging. When lithium flows from the anode during discharge, the anode shrinks to its original size and the coating cracks, exposing fresh silicon for electrolytes.
Just a few cycles, an extension and contraction in conjunction with electrolytes attack destroys the anode in a process called "decrepitation."
During the previous five years, the group gradually increased durability Kyuy silicon anodes by making them out of nanowires and then hollow silicon nanoparticles. Their new sample consists of dvustenochnoy silicon nanotubes coated with a thin layer of silicon oxide - a very strong ceramic material.
This strong outer layer keeps the outer wall of the nanotube from expanding, so that it remains intact. Instead of expanding outward, silicon successfully fills the interior of the hollow between the two walls, the sizes are too small to qualify for electrolyte molecules. After 6000 cycles, it retains 85 percent of its original capacity.
Kyuy said that further studies will be aimed at simplifying the process of creating a double-walled silicon nanotubes. Part of his group is working to develop new high-cathode, which will be a couple of new anode in the form of a battery, the capacity of which is five times larger than the modern models of lithium-ion batteries.
In 2008 Kyuy founded Amprius, which owns the rights to patents developed at Stanford they silicon nanowire anodes.