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New all-solid Li-S battery from ORNL shows approximately 4x energy density of current Li-ion batteries

6 June 2013

Researchers at Oak Ridge National Laboratory (ORNL) have designed and tested an all-solid lithium-sulfur battery with approximately four times the energy density of conventional lithium-ion technologies. The ORNL battery design also addresses flammability concerns experienced by other chemistries.

Despite the theoretical promise of high energy density in rechargeable Li-sulfur batteries, commercialization has been retarded by the reduced cycle life enabled by the liquid electrolytes. While the liquid helped conduct ions through the battery by allowing lithium polysulfide compounds to dissolve, the same dissolution process caused the battery to break down prematurely. (e.g., Earlier post.)

The ORNL team overcame these barriers by first synthesizing a new class of sulfur-rich materials—lithium polysulfidophosphates (LPSPs)—that conduct ions as well as the lithium metal oxides conventionally used in the battery’s cathode.

LPSPs have ionic conductivities of 3.0×10−5 S cm−1 at 25 °C, which is 8 orders of magnitude higher than that of Li2S (lithium sulfide). The high lithium ion conductivity imparts excellent cycling performance, the researchers noted.

The researchers then combined the new sulfur-rich cathode and a lithium anode with a solid electrolyte material, also developed at ORNL, to create an energy-dense, all-solid battery.

A paper on their work is published in the journal Angewandte Chemie International Edition.

Our approach is a complete change from the current battery concept of two electrodes joined by a liquid electrolyte, which has been used over the last 150 to 200 years. This game-changing shift from liquid to solid electrolytes eliminates the problem of sulfur dissolution and enables us to deliver on the promise of lithium-sulfur batteries. Our battery design has real potential to reduce cost, increase energy density and improve safety compared with existing lithium-ion technologies

—Chengdu Liang, lead author

The new ionically-conductive cathode enabled the ORNL battery to maintain a capacity of 1,200 mAh/ g after 300 charge-discharge cycles at 60 °C. By comparison, a conventional lithium-ion battery cathode has an average capacity between 140-170 mAh/g. Because lithium-sulfur batteries deliver about half the voltage of lithium-ion versions, this eight-fold increase in capacity demonstrated in the ORNL battery cathode translates into four times the gravimetric energy density of lithium-ion technologies, explained Liang.

The team’s all-solid design also increases battery safety by eliminating flammable liquid electrolytes that can react with lithium metal. Chief among the ORNL battery’s other advantages is its use of elemental sulfur, a plentiful industrial byproduct of petroleum processing.

Although the team's new battery is still in the demonstration stage, Liang and his colleagues hope to see their research move quickly from the laboratory into commercial applications. A patent on the team’s design is pending.

In addition to Liang, coauthors are ORNL’s Zhan Lin, Zengcai Liu, Wujun Fu and Nancy Dudney. The research was sponsored by the US Department of Energy, through the Office of Energy Efficiency and Renewable Energy's Vehicle Technologies Office. The investigation of the ionic conductivity of the new compounds was supported by the Department's Office of Science.

The synthesis and characterization was conducted at the Center for Nanophase Materials Sciences at ORNL. CNMS is one of the five DOE Nanoscale Science Research Centers (NSRCs) supported by the DOE Office of Science, premier national user facilities for interdisciplinary research at the nanoscale.

Together the NSRCs comprise a suite of complementary facilities that provide researchers with advanced capabilities to fabricate, process, characterize and model nanoscale materials, and constitute the largest infrastructure investment of the National Nanotechnology Initiative.

The NSRCs are located at DOE’s Argonne, Brookhaven, Lawrence Berkeley, Oak Ridge and Sandia and Los Alamos national laboratories.

Resources

  • Lin, Z., Liu, Z., Fu, W., Dudney, N. J. and Liang, C. (2013), Lithium Polysulfidophosphates: A Family of Lithium-Conducting Sulfur-Rich Compounds for Lithium-Sulfur Batteries . Angew. Chem. Int. Ed. doi: 10.1002/anie.201300680

June 6, 2013 in Batteries | Permalink | Comments (9) | TrackBack (0)

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The various sulphide batteries do have high energy densities. These energy densities will not ever be able to surpass those of methanol even, whilst using air. The NGK sulphur batteries have shown the ability to burn, but this can be controlled and limited and such are very suitable for rapid charging stations so that the local grid is not overloaded. The NOAX chiron free piston engine could be developed to give a very high efficiency range extender for any electric vehicle, but might give better service at lower cost in a hydraulic hybrid. ..HG..

Very interesting indeed. However the paper does mention a relatively low energy efficiency : 83% at 60°C and only 60% at room temperature (25°C). This is not really good news regarding practical range for an electric vehicle, nor electric consumption from the grid. Does anyone know if it can be improved ?

@aha:
Thanks for passing on the info on low efficiency.
That is the sort of thing which doesn't get mentioned in write-ups, so we are all left wondering:
'Whatever happened to.....?'

@ HG:
Considering the improvements that have been achieved in catalytic designs (ref. to):
http://www.greencarcongress.com/2013/06/lanl-20130605.html
that'll surely benefit future battery and FCs design.
I'd personally prefer FCs as range extenders instead of fossil fuel burning contraptions.

It seems everyone assumes that Li should be the anode for a sulfur based cathode. I don't get it. Also, why did they use a solid electrolyte? Wasn't the purpose of the new sulfur compound supposed to be the elimination of polysulfides and if not why did they do it at all. Higher conductivity? That's not really why sulfur has problems.

Most of the inefficiency is from the solid electrolyte, energy lost to heat from the high impedence. Thus, as you warm the cell the impedence drops and the efficiency gets better.

It's an interesting cathode, maybe someone who actually wants to achieve success will adapt it to better cell, or in other words a better electrolyte and anode.

This battery technology could be the win-win-win unit that electrified vehicles have been waiting for.

The potential 600+ Wh/Kg energy density, increased safety and lower cost could make future extended range EVs safe and affordable?

The lower efficiency (80% versus 90%) is not a real problem because e-energy is much cheaper, cleaner and sustainable than liquid fuels. Overnight charging cost 1/5 or less than gasoline in many places.

Overloading the grid is a scare than many posters are falsely promoting. Producing more clean electricity and re-enforcing the grid is something we have known how to do for many decades. Proven technologies are all there to do it. It is not a real challenge.

Let's stop taking others for a ride?

@brotherkenny:
You apparently can't understand the rationale for using a solid electrolyte:

'Despite the theoretical promise of high energy density in rechargeable Li-sulfur batteries, commercialization has been retarded by the reduced cycle life enabled by the liquid electrolytes. While the liquid helped conduct ions through the battery by allowing lithium polysulfide compounds to dissolve, the same dissolution process caused the battery to break down prematurely.'

So you resort to some half-baked conspiracy theory that they are not really trying to make batteries work.

"The cathode shows an initial discharge capacity of 1272 mAh/g (based on the incorporated sulfur content) or 599 mAh/g (based on the compound ; Figure 3 a)." In the Li-S research world, it's common practice to normalize cathode capacity according to the active cathode mass and ignore the inactive mass. However, to calculate total cell energy density, one must consider the entire electrode mass, including both the active and inactive mass. Perhaps the inactive mass in Li-S cathodes can be reduced over time, but today, Li-S cathodes have a much higher inactive mass (~50%) than Li-ion cathodes (~15%).

Davemart,

No, no half baked conspiracy theory, just a fully baked theory that the researchers are twits. If they are making these for cars they are worse than twits. If they are making these for solar or wind then they should lower there rate where the losses are way less. No, no conspiracy, just twits.

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