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All-solid lithium-sulfur battery stores four times the energy of lithium-ions

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June 7, 2013

Researchers are building an all-solid Li-S battery that is cheap, safe, durable, and store...

Researchers are building an all-solid Li-S battery that is cheap, safe, durable, and stores four times the charge of conventional lithium-ion batteries (Photo: ORNL)

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Researchers at the Oak Ridge National Laboratory (ORNL) have come up with a promising design for a lithium-sulfur rechargeable battery that is considerably cheaper and energy-dense than standard lithium-ions. Using a solid electrolyte rather than a liquid one, the battery is also testing much safer and more durable than previous designs.

Lithium-sulfur batteries are seen by some as the successors of lithium-ions because they are extremely light (they are often used for solar-powered flight), they can reach an impressive energy density, and they are cheaper to produce.

But the technology isn't quite mature yet, and as it turns out, the two major limitations with Li-S batteries have to do with the electrolyte. An electrolyte is a substance that, when mixed with a solvent, releases ions, making it electrically conductive. In batteries, electrolytes transport charge between the two electrodes, converting chemical energy into electrical energy.

In previous Li-S battery designs, the electrolyte used was liquid in nature. This proved a double-edged sword: the liquid electrolyte is an excellent conductor because of how it dissolves the lithium compounds, but this dissolution also causes the battery to break down prematurely. The liquid electrolyte is also flammable, posing serious safety concerns.

But now, researchers may have found a way around these problems.

"Our technology overcomes the capacity fade and safety issues of Li-S technology," Dr. Chengdu Liang, lead author of a paper on the research, told Gizmag. "The battery still performs well after a few hundred cycles, and the volumetric density could be slightly better than Li-ion batteries."

The new Li-S battery design overcomes the problems with previous attempts (Photo: ORNL)

The researchers overcame these barriers by building a solid electrolyte made of lithium polysulfidophosphates (a new class of sulfur-rich materials with good electrical conductivity) to create an energy-dense, all-solid battery that is showing a lot of promise.

Even after 300 charge-discharge cycles at 60°C (140ºF), the battery retained a capacity of 1200 mAh/g (milliampere-hours per gram), compared to the 140-170 mAh/g of a traditional lithium-ion battery (lithium-sulfur batteries, however, only deliver about half the voltage of lithium-ions, so this 8-fold increase actually translates into a 4-fold increase in energy density).

The battery uses elemental sulfur, which is a byproduct of industrial petroleum processing. In other words, the battery could also provide a way to recycle industrial waste into a useful – perhaps even superior – technology.

"The main limitation is the relatively low ionic conductivity of the solid electrolyte," said Liang. "So the power density is lower than Li-ion batteries, but it can be improved with a better solid electrolyte. Moreover, the ceramic structure is brittle, and much optimization is needed."

The technology is still in the early stages of development, but Liang and colleagues are working on ironing out these issue and have filed a patent application for their battery design.

The paper detailing the study was recently published in the journal Angewandte Chemie.

Update 06.10.13: Gizmag wrote back to Dr. Chengdu Liang for more details of the battery's charging and discharging behavior. Here is his response:

"We did not observe self-discharge. A charged cell was put on shelf for over a week, and it still delivered the same capacity. The essence of our all-solid battery design is to eliminate the self-discharge through the all-solid configuration.

"This battery charges slower than Li-ion battery at the current status for a simple reason; the ionic conductivity of both the solid electrolyte and cathode are not high energy to have high current density. Much better performance at elevated temperatures such as 60 degrees C or higher."

Source: ORNL

About the Author
Dario Borghino Dario studied software engineering at the Polytechnic University of Turin. When he isn't writing for Gizmag he is usually traveling the world on a whim, working on an AI-guided automated trading system, or chasing his dream to become the next European thumbwrestling champion.   All articles by Dario Borghino
17 Comments

This sounds really good. So.. whats the catch? xD

If this becomes a reallity just imagine..

asdf
7th June, 2013 @ 12:38 pm PDT

It means I can fly my rc planes 20+ minutes instead of 10 mins/charge. That's a good thing.

JimD
7th June, 2013 @ 02:01 pm PDT

My Quadrocopter will go from 7 minutes to 28mins =) Sweet!

Fredrik Johannes Haugen
8th June, 2013 @ 03:37 pm PDT

What is its self discharge rate?

How long does it take to charge?

Slowburn
8th June, 2013 @ 10:28 pm PDT

If there is to be a last longer battery, the gadget constructors will also make more powerful gadgets, (phones, tablets, laptops etc) and thus making them more power hungry. We will still struggle with 6 hours phones on a single charge.

Incra Mant
9th June, 2013 @ 03:43 am PDT

It must be coming the replacement for the LI-ON.

With 70 odd million tonnes of Sulphur being produced a year this would be a handy use for it, if only Lithium poured out of petroleum as well!

Also ^ Slowburns question + 1

Craig Jennings
9th June, 2013 @ 02:47 pm PDT

Quite surprised carbon nanotubes did not pop up in this article - curious to know if they looked at nanotube networks coated with the lithium sulphur technology. Guess this may of put it into the box where it looks great but have we actually seen any of it come to fruition.

myale
10th June, 2013 @ 02:28 am PDT

Well, if I understand the article right, the bottleneck is the max. current that can be drawn out of these. Offering a higher capacity, they seem suited to applications that do not drain them too fast, so it's probably not R/C planes, as these are notorious for high discharge rates.

Instead, my electric car could run a lot longer with tech like this, as cars do discharge at a relatively low rate, surprisingly, for many. For comparison: An R/C plane drains a battery in minutes, an electric car in hours. I'll follow this.

martinkopplow
10th June, 2013 @ 03:45 am PDT

Slowburn's question +2 now

Foiled
10th June, 2013 @ 04:32 am PDT

An electric car with such a battery would have a 300 miles range and would hopefully cost 20000$ rather than 40000$.

Anyway, about current drain, I know e-scooter drain 40-80 Ampere (for 2000-5000W range, 48-72V range).

Don't know about cars.

jumpjack
10th June, 2013 @ 07:30 am PDT

Hey, GREAT! Just throw in a little aluminum dust with the sulfur electrolytes, and bingo! LOL! Seriously, the day is coming when we WILL have the best battery for particular uses. They have said for decades that the "battery technology" was the weakest point... but now it is becoming so important that the "solutions" will be found....

Observer101
10th June, 2013 @ 09:33 am PDT

Use this for EVs? awesome.

Stephen N Russell
10th June, 2013 @ 09:35 am PDT

I don't get it: the thing's got 4X the energy density, but the researcher says only that "the volumetric density could be slightly better than Li-ion batteries": Is he saying that it's only slightly lighter for a given volume?

mookins
10th June, 2013 @ 10:25 am PDT

re; mookins

Energy density can be measured by weight or volume. By weight Hydrogen is a very high energy density fuel but by volume Hydrogen is a very low energy density fuel.

Slowburn
10th June, 2013 @ 11:26 pm PDT

Seems like they are constantly finding new materials that are better then the old ones, and while batteries today are quite abit better then 5 years ago, like most technologies its frusterating how long it takes from the time of discovery until its commercial feasible.

Likely by the time this technology is being produced commercially it will have already been far surpassed by new discoveries. Its just a shame these couldn't be made useful alot quicker is all. I see this alot specifically with solar cell technology, there is a ton of technology far more efficient and supposedly cheaper then what is on the market today and it seems like every couple months some new break through is achieved.

I'm not 100% sure what slows it down from coming to market, but i can't help but suspect that a big part of it is regulations of some sort, red tape when it comes to patents, bureaucracy etc etc.

I think if improvements were made to the whole system that manages how new technology is brought to market, scientific advancement would be greatly accelerated and it could have a compounding effect over the years.

Atleast thats how it appears to me, admittedly no expert, just an amateur observer.

Nathaneal Blemings
13th June, 2013 @ 09:39 pm PDT

"curious to know if they looked at nanotube networks coated with the lithium sulphur technology."

Dammit, myale, that was MY idea !

Graphene plates layered with Li-S electrolyte, stacked a thousand layers deep.

Or maybe dope the Li-S electrolyte with fullerenes as charge carriers?

Up to a critical point, adding fullerenes should boost the conductivity. Too much, and you might have a negative effect.

We need cells robust enough to handle the high temperatures we'd see in cars; small enough to robotically swap them out at Charge Stations, and easy to recycle when they hit the 2,000 cycle mark.

This brings back the "leasing batteries" plan; you don't own the batteries, you own the car.

You LEASE the batteries, and the provider creates a network of Charge Stations where the batteries are periodically swapped, charged, tested, and leased out again.

When the batteries drop below the 70% threshold, they can be sold for home backup cells, or ground up to recover the Lithium.

Carbon and Sulfur, we have plenty of.

William Carr
14th June, 2013 @ 10:30 am PDT

I bet I'll find a way to drain it in a tenth of the time it takes to charge it.

Nitrozzy Seven
15th June, 2013 @ 10:37 am PDT
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