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Hybrid anode quadruples the lifespan of lithium-sulfur batteries


February 20, 2014

A shield around the anode made from graphite, a material that is used in lithium-ion anodes, contains unwanted polysulfides and improves the lifespan of the battery by a factor of four

A shield around the anode made from graphite, a material that is used in lithium-ion anodes, contains unwanted polysulfides and improves the lifespan of the battery by a factor of four

Increasing the range of electric vehicles and improving the storage of renewable energy systems are two examples of the benefits offered by lithium-sulfur batteries. Though they can hold four times the energy per mass of the lithium-ion batteries used today, their considerably shorter lifespan has proven something of a roadblock. Researchers from the Pacific Northwest National Laboratory (PNNL) have now designed a lithium-sulfur battery with four times the longevity, bringing the technology that little bit closer to maturity.

The team's research looked to solve a problem posed by a chemical reaction between the batteries two electrodes, where the sulfur-containing cathode corrodes the lithium-containing anode, substantially shortening the battery's life.

Over time, the anode disintegrates, with the sulfur dissolving into molecules called polysulfides which pass into the battery's electrolyte solution. As this liquid works as a highway for ions to move from one electrode to the other, the polysulfides follow suit and ultimately cause a thin film to form on the anode's surface. This film grows thicker until the battery is entirely inoperable, in effect shortening its life dramatically.

Rather than looking at ways to minimize the leakage, as previous research has explored, the team devised a way to protect the anode from the damaging molecules of the sulfur-containing cathode. Building a shield around the anode made from graphite, a material that is used in lithium-ion anodes, the team were able to contain the troublesome polysulfides and improve the lifespan of the battery by a factor of four.

"Sulfur is still dissolved in a lithium-sulfur battery that uses our hybrid anode, but that doesn't really matter," says PNNL Laboratory Fellow and one of the study's authors Jun Liu. "Tests showed a battery with a hybrid anode can successfully be charged repeatedly at a high rate for more 400 cycles, and with just an 11-percent decrease in the battery's energy storage capacity."

The team's research was published in the journal Nature Communications.

Source: PNNL

About the Author
Nick Lavars Nick was born outside of Melbourne, Australia, with a general curiosity that has drawn him to some distant (and very cold) places. Somewhere between enduring a winter in the Canadian Rockies and trekking through Chilean Patagonia, he graduated from university and pursued a career in journalism. Having worked for publications such as The Santiago Times and The Conversation, he now writes for Gizmag from Melbourne, excited by tech and all forms of innovation, the city's bizarre weather and curried egg sandwiches. All articles by Nick Lavars

400 cycles with ONLY an 11 per cent reduction in storage capacity ? Is that supposed to be good ? If this battery was in an electric car that was put on charge, after being used for the day, then the batteries would be about 10 per cent wrecked in the first year. Compare that to a diesel or petrol engine that would show no drop in performance at all in this time.......



Read the article again. The technology has matured for a bit, but it still isn't there yet. This research has made more success towards realizing the ever more important goal of more energy dense batteries, in regards to considerable improving the performance of its charge cycles than other research teams.

It is too early to put this technology in anybody's car, so don't put it in that context (yet). Just imagine that same bulky battery in an electrical car, being eventually replaced with one 1/4 the weight. It is only a matter of time.

Fretting Freddy the Ferret pressing the Fret

Some things are counter-intuitive. A battery that loses 11% of its capacity after "only" 400 cycles seems like it would not be a commercially competitive product. But consider this:

These lithium sulfur batteries have about 2-4x the energy density of current lithium ion batteries. A Tesla Model S gets 265 miles on a charge.

Even when using the lower density number, 2x, a Model S would get 530 miles of range per charge. After putting 212,00 miles on the odometer, it would still work, but only get about 470 miles of range per charge.

That's after 17 years of use at an average of 12,000 miles per year.

During which you would have saved about $31,800 in fuel costs.

I'll take one of these lithium sulfur batteries now, pleeze.
There are so many breakthroughs in battery technology that investors may be a bit frightened as dedicating money to build factories that just might be obsolete before the first battery rolls of the line is a real issue. The other guys battery is likley to be even better. Jim Sadler

Good point Jim, but what about your computer? I know its an order of magnitude cheaper (or two) than a car, but still, they fly off the shelves just as obsolete as can be...


It will be interesting to see if Tesla is interested . . . PNNL - 'transform the world through courageous discovery and innovation'

Jeffrey Edwards
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