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Cellphone Battery Boost? Fool's Gold Dots Boost Performance

Nov 17, 2015 04:49 PM EST

Could fool's gold be a valuable commodity after all? Researchers at Vanderbilt University believe that iron pyrite, as it's also known, could be used to make better batteries. In fact, after making quantum dots -- super-tiny semiconductors -- out of fool's gold, researchers discovered they could create lithium batteries that charge quickly and can last for more recharge cycles, according to a news release.

Fool's gold is commonly mistaken as precious gold for its similar metallic luster. However, the two minerals actually have very different tones of yellow: Gold is golden to silvery yellow, while pyrite is more of a pale yellow. Additionally, gold is often found in nuggets, small flakes or sheets, and pyrite is cubic and octahedral.

Researchers were initially interested in iron pyrite because of its abundance on Earth -- it is actually one of the most abundant minerals because it is produced as a byproduct of coal production, meaning it is also cheap to use in single-use lithium batteries.

Previous research has failed to successfully use nanoparticles to improve battery performance, because when the particles are shrunk to a certain size, they chemically react with electrolytes of batteries enough to limit the number of charge cycles they can endure. Therefore, the new study aimed at combining millions of iron pyrite with quantum dots of different sizes to overcome this challenge. (Scroll to read more...)

(Photo : John Russell, Vanderbilt University)
Vanderbilt graduate student holding one of the batteries modified by adding millions of quantum dots made from fool's gold.

When researchers added the newly designed quantum dots to standard lithium batteries, they discovered they could substantially improve both the batteries' cycling and rate capabilities. This is because iron pyrite has a unique way of changing form to store energy, the release noted.

"This is a different mechanism from how commercial lithium-ion batteries store charge, where lithium inserts into a material during charging and is extracted while discharging -- all the while leaving the material that stores the lithium mostly unchanged," Anna Douglas, a Vanderbilt graduate student, explained in the release. "Instead of just inserting lithium or sodium ions in or out of the nanoparticles, storage in iron pyrite requires the diffusion of iron atoms as well. Unfortunately, iron diffuses slowly, requiring that the size be smaller than the iron diffusion length -- something that is only possible with ultra-small nanoparticles."

This study provides a better understanding of chemical storage mechanisms and how they depend on nanoscale dimensions, which could ultimately lead to the development of more efficient batteries.

Their findings were recently published in the journal ACS Nano.

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