Chemists one step closer to new generation of electric car battery

January 12, 2015, University of Waterloo

An ultra-thin nanomaterial is at the heart of a major breakthrough by Waterloo scientists who are in a global race to invent a cheaper, lighter and more powerful rechargeable battery for electric vehicles.

Chemistry Professor Linda Nazar and her research team in the Faculty of Science at the University of Waterloo have announced a breakthrough in lithium-sulphur in a recent issue of Nature Communications.

Their discovery of a material that maintains a rechargable sulphur cathode helps to overcome a primary hurdle to building a lithium-sulphur (Li-S) battery. Such a battery can theoretically power an electric car three times further than current lithium-ion batteries for the same weight - at much lower cost.

"This is a major step forward and brings the lithim-sulphur battery one step closer to reality," said Nazar, who also holds the Canada Research Chair in Solid State Energy Materials and was named a Highly Cited Researcher by Thomson Reuters.

Nazar's group is best known for their 2009 Nature Materials paper demonstrating the feasibility of a Li-S battery using nanomaterials. In theory, sulphur can provide a competitive cathode material to lithium cobalt oxide in current lithium-ion cells. Sulphur as a material is extremely abundant, relatively light, and very cheap.

Unfortunately, the sulphur cathode exhausts itself after only a few cycles because the sulphur dissolves into the electrolyte solution as it's reduced by incoming electrons to form polysulphides.

Nazar's group originally thought that porous carbons or graphenes could stabilize the polysulphides by physically trapping them. But in an unexpected twist, they discovered metal oxides could be the key. Their initial work on a metallic titanium oxide was published earlier in August in Nature Communications.

While the researchers found since then that nanosheets of manganese dioxide (MnO2) work even better than titanium oxides, their main goal in this paper was to clarify the mechanism at work.

"You have to focus on the a fundamental understanding of the phenomenon before you can develop new, advanced materials," said Nazar.

They found that the oxygenated surface of the ultrathin MnO2 nanosheet chemically recycles the sulphides in a two-step process involving a surface-bound intermediate, polythiosulfate. The result is a high-performance cathode that can recharge more than 2000 cycles.

The surface reaction is similar to the chemical process behind Wackenroder's Solution discovered in 1845 during a golden age of German sulfur chemistry.

"Very few researchers study or even teach sulphur chemistry anymore," said Nazar. "It's ironic we had to look so far back in the literature to understand something that may so radically change our future."

Postdoctoral research associate Xiao Liang, the lead author, and graduate students Connor Hart and Quan Pang also discovered that graphene oxide seems to work by a similar mechanism. They are currently investigating other oxides to find the best sulphur retaining material.

BASF International Scientific Network for Electrochemistry and Batteries funded the research. The paper's co-authors include Arnd Garsuch and Thomas Weiss of BASF.

Professor Nazar will present on the promise and reality of lithium-sulfur batteries at the American Association for the Advancement of Science (AAAS) Annual Conference on Saturday, February 14, 2015 in room 230B in the San Jose Convention Center.

Explore further: Major breakthrough in lithium battery technology reported

More information: Nature Communications, … full/ncomms6682.html

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1.7 / 5 (14) Jan 12, 2015
Yet another University promising "3 times this" and "many time lighter and cheaper than that" posting failed laboratory work following 1845 theory that has proved always not to work.

Here's hoping for grant money for saying "climate change"
3.7 / 5 (6) Jan 12, 2015
Good work, green. I had to put otto on Ignore for the same negative nonsense. I do not know if it is political or psychological.

With all these recent developments, I wonder if the designers for the new battery factory are nervous about which technology to back?
1 / 5 (3) Jan 12, 2015
After alternative energy and storage kills off nukes and coal, will we get the pro-nukers and coal folk to clean up what they contaminated?
5 / 5 (1) Jan 14, 2015
@gkam: to lump nukes and coal together is disingenuous. The amount of damage coal has done outstrips nukes by several orders of magnitude (using terrawatt/hrs), even including all nuclear accidents AND atom bombs.

Alternative energy and storage will hopefully outcompete coal, but next gen nukes should really be considered part of a smart energy equation for the future.
1 / 5 (2) Jan 14, 2015
The electronegativity between Li and C which is the Lithium Ion battery anode and cathode is almost the same as between Li and S but sulfur weighs 2.5 times more. So how can it be said that Li-S is lighter and holds more energy per kilogram. Somebody in angling for government money and that is all that this is about.
5 / 5 (1) Jan 14, 2015
A useful power and cycle life improvement. It will keep the Lithium battery industry selling "New and Improved" products until Magnesium-Sulphur comes to market:-
Then perhaps 'affordable car' will mean less than $30,000!
5 / 5 (1) Jan 14, 2015
The electronegativity between Li and C which is the Lithium Ion battery anode and cathode is almost the same as between Li and S but sulfur weighs 2.5 times more. So how can it be said that Li-S is lighter and holds more energy per kilogram. Somebody in angling for government money and that is all that this is about.

No, Li-S is lighter than LiNixMnyCozO2.
2.3 / 5 (3) Jan 15, 2015
One more step in a 5,000 mile journey. Enough with the updates every time another step is taken, just let me know when the finish line has been reached.

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