40,000 Cycles — Nanotechnology Catapults Battery Technology Forward, Once Again

November 24th, 2011 by Nicholas Brown

Yi Cui, a Stanford University professor of materials science and engineering, has led researchers to yet another breakthrough in battery technology, but this time, it is not lithium-ion.

For those that don’t already know, electric vehicles need batteries with a low cost and a long lifespan, and solar and wind power plants can benefit significantly from batteries like that as well. Storing solar and wind power for later use not only facilitates selling it at any time of day with no backup generators, but it eliminates reliability issues and fluctuations in electricity generation.

Stanford University researchers have demonstrated a battery technology that is able to retain 83% of it’s charge after 40,000 cycles. (1 cycle is 1 charge and 1 discharge.) Lead acid batteries only last a few hundred cycles, and lithium-ion 1,000.

Please note that the cycle life of batteries is not the same as their shelf life. Some batteries, such as li-ion self-degrade even when not being used. Lithium-ion batteries would last 19 years if they did not self-degrade, due to the fact that they have a cycle life of 1,000 cycles, assuming that they are cycled once per week.

This new battery technology is similar to lithium-ion batteries but can use either sodium or potassium ions instead of lithium ions. Sodium and potassium are much more abundant and cheaper than lithium.

What the researchers did was start with a pigment called “Prussian Blue,” which is a compound of iron and cyanide, and they replaced half of the iron with copper, then they manufactured crystalline nanoparticles of the compound. Then they coated it on a cloth resembling carbon substrate. Then, finally, they submerge it in an electrolyte solution called potassium nitrate.

The electrodes exhibited 99% efficiency. “You want the voltage you put in during charging and the voltage you take out during discharge to be same,” Cui says. “Compared to any other battery material, this is absolutely the best.”

This does have a drawback for weight-sensitive applications such as electric vehicles, though: this has an energy density of only 60 mAh per gram. Apart from that, this is definitely a technology I want to keep an eye on. Power plants are not weight-sensitive.

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h/t Technology Review | photo via Voxphoto









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