Stable "superoxide" opens the door to a new class of batteries

January 13, 2016 by Jared Sagoff
A team of Argonne researchers (from left, Khalil Amine, Jun Lu, Larry Curtiss, Zonghai Chen, Kah Chun Lau, and Hsien-Hau Wang) have developed a way to create stable lithium superoxide in a lithium-air battery system.

While lithium-ion batteries have transformed our everyday lives, researchers are currently trying to find new chemistries that could offer even better energy possibilities. One of these chemistries, lithium-air, could promise greater energy density but has certain drawbacks as well.

Now, thanks to research at the U.S. Department of Energy's (DOE's) Argonne National Laboratory, one of those drawbacks may have been overcome.

All previous work on -air batteries showed the same phenomenon: the formation of (Li2O2), a solid precipitate that clogged the pores of the electrode.

In a recent experiment, however, Argonne battery scientists Jun Lu, Larry Curtiss and Khalil Amine, along with American and Korean collaborators, were able to produce stable crystallized lithium superoxide (LiO2) instead of lithium peroxide during battery discharging. Unlike lithium peroxide, lithium superoxide can easily dissociate into lithium and oxygen, leading to high efficiency and good cycle life.

"This discovery really opens a pathway for the potential development of a new kind of battery," Curtiss said. "Although a lot more research is needed, the cycle life of the battery is what we were looking for."

The major advantage of a battery based on lithium superoxide, Curtiss and Amine explained, is that it allows, at least in theory, for the creation of a lithium-air battery that consists of what chemists call a "closed system." Open systems require the consistent intake of extra oxygen from the environment, while closed systems do not—making them safer and more efficient.

The lattice match between LiO2 and Ir3Li may be responsible for the LiO2 discharge product found for the Ir-rGO cathode material. Credit: Argonne/Larry Curtiss

"The stabilization of the superoxide phase could lead to developing a new closed system based on lithium superoxide, which has the potential of offering truly five times the energy density of ," Amine said.

Curtiss and Lu attributed the growth of the lithium superoxide to the spacing of iridium atoms in the electrode used in the experiment. "It looks like iridium will serve as a good template for the growth of superoxide," Curtiss said.

"However, this is just an intermediate step," Lu added. "We have to learn how to design catalysts to understand exactly what's involved in ."

Explore further: New battery technologies take on lithium-ion

More information: Jun Lu et al. A lithium–oxygen battery based on lithium superoxide, Nature (2016). DOI: 10.1038/nature16484

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1.3 / 5 (3) Jan 13, 2016
Open systems require the consistent intake of extra oxygen from the environment, while closed systems do not—making them safer and more efficient.

That's like saying that carbon and salt peter are safer stored together than separated, nevermind the fact that combined they form gunpowder.

The lithium-air batteries are safer (and lighter) because the oxygen remains stored in the atmosphere rather than in the battery, where it would be readily available to react violently when the cell gets damaged. When both the oxidizer and the material to be oxidized are enclosed in the same battery, you're literally sitting on a powder keg.

5 / 5 (2) Jan 13, 2016
Hi Eikka,

You make a good analogy, but every battery has energy in it, just as every bomb does. The only difference is how fast it will expend that energy. It's not clear from the article that this design would instantly discharge in destruction anymore than any other lithium battery. And don't get me wrong, lithium batteries are known to catch fire and can be hazardous, but I don't see a 5x energy density as being 5x more life threatening.

My short google search, shows Lithium-ion AA batteries at 11050 joules and 24g, and Black powder when burned typically releases 3 Megajoules per kilogram of energy.

Powder would then be 3 kilojoules per gram, current Lithium at 240 kj/g, at 5x improvement, it would put these new batteries with in an order of magnitude of gun powder, but still short by about 50%. It's a great improvement in density!
5 / 5 (2) Jan 14, 2016
'...for the creation of a lithium-air battery that consists of what chemists call a "closed system."' I'm sure they just weren't thinking when they said this... Sadly, it still hurts to read it.

Anyways, getting past grammar policing...

From this article here: http://jes.ecsdl....full.pdf
Their theoretical battery only a little more than halves in density to 5,200 Wh/kg
from 11,140 Wh/kg if made as a closed system that includes the oxygen.

It seems any realization of Li-O battery tech would be an incredible leap forward in density, even as a closed system.

I hope this super oxide tech turns out to be safe and cheaply mass manufacturer-able. :)
5 / 5 (1) Jan 16, 2016
I think they need to rethink the materials, since to me my knowledge Iridium is a rare. And as so it means expensive. Maybe they can find other material with similar lattice structure.
2 / 5 (2) Jan 17, 2016
It's not clear from the article that this design would instantly discharge in destruction

But that is beside the point.

I was merely pointing out that their reasoning as to why a "closed system" is safer doesn't make any sense.

And modern lithium batteries do burn very much in the same fashion as gunpowder. The difference is that gunpowder - when not tightly enclosed or finely dispersed - doesn't actually burn very vigorously. If however you were to put either in a tightly sealed canister able to withstand some pressure, and light them, both will turn into a bomb.

That's why all lithium battery cells are built with a pressure relief. There's enough energy in them, and they do react rapidly enough to make an explosion hazard, and with a higher energy density it's just going to get worse and worse. At some point you'll be able to put a blasting cap between two pouch cells and get them to detonate.

That's why the "closed system" is not safer.

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