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Batteries pnnl lithium sulfur battery

Published on April 17th, 2014 | by Tina Casey

18

“Unique Powdery Nanomaterial” Could Blow Up EV Range Anxiety

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April 17th, 2014 by  

When it comes to soothing EV range anxiety, the lithium-sulfur combo offers a lot of promise, but until now there’s been a catch (there’s always a catch). Li-S batteries have a much shorter life cycle than the gold standard, lithium-ion, which makes them a poor bet for the mass market. However, researchers at Pacific Northwest National Laboratory (PNNL) may be on to a solution.

If the research leaps the Valley of Death from the lab to the market, that could spell the end of the gasmobile as we know it. According to PNNL, an Li-S battery could store up to four times more energy per mass than an Li-ion battery.

pnnl lithium sulfur battery

Metal organic framework courtesy of PNNL.

The Sulfur Cure For EV Range Anxiety

As noted above, Li-S offers far greater energy storage potential than Li-ion, but as of right now if you had an Li-S battery in your EV, you would have range anxiety on an epic scale.

The problem is the sulfur cathode (the positively charged electrode). The cathode sits in an electrolyte bath and researchers have been stuck on how to get the sulfur to stop disintegrating into the bath.

Since the disintegration is not reversible, the cathode quickly loses sulfur and there goes your Li-S battery.

A Better Sulfur Battery

Last spring, researchers at Oak Ridge National Laboratory announced one pathway to solving the life cycle problem last spring, based on a solid electrolyte in combination with a sulfur-enriched cathode and a lithium anode (the negatively charged electrode).

The new PNNL solution focuses in on a “unique, powdery nanomaterial” that can ensnare polysulfides in the cathode. Called a metal organic framework, it is a crystalline compound of metal clusters linked by organic molecules, which self-assemble into a porous structure.

If that sounds familiar, you may be thinking of gas-trapping technology based on metal organic frameworks. Their use in EV batteries represents a new field.

Think of a metal organic framework as a high tech, nanoscale sponge and you’re on the right track. Since nickel interacts strongly with sulfur, the heart of the PNNL “sponge” is a positively charged nickel center.

So far, the research team has been able to get their Li-S battery to retain 89 percent of its initial capacity after 100 charging cycles. The next step is to improve the storage capacity of the cathode and scale the whole thing up.

EV Supply Chain Anxiety

One of the concerns about transitioning to a full-on global EV market is the availability of specialty materials that go into EV batteries.

That opens up a whole new can of worms in terms of supply chain geopolitics.

In that context, sulfur does not open up a new can of worms. It is a common material (“practically free,” enthuses one enthusiastic Oak Ridge scientist), and vast quantities are produced as a byproduct of fossil fuel refining. Researchers at the University of Arizona are already finding that waste sulfur from fossil fuel refining can be used in Li-S batteries (it can also be converted to plastic, for that matter).

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About the Author

Tina Casey specializes in military and corporate sustainability, advanced technology, emerging materials, biofuels, and water and wastewater issues. Tina’s articles are reposted frequently on Reuters, Scientific American, and many other sites. Views expressed are her own. Follow her on Twitter @TinaMCasey and Google+.



  • Otis11

    This completely overlooks the main issue causing range anxiety – we don’t need more energy/kg, we need more energy/$! We have plenty of room and can handle heavier cars (though it’s not prefered as there are trade-offs). As Tesla has shown, we can easily get a 250+ mile range out of existing technology if we’re willing to pay for it – and still have room to spare! The problem: that big of a battery is currently expensive!

    We should be discussing Kwh/$…

    And the rarity thing – there’s more than enough currently known and economically extractable materials to make enough Li-ion batteries to power the developed world. This has been covered in previous comment discussions (though I forget who went through all of the math…).

    • Bob_Wallace

      Tesla and BYD both prove that we can build longer range EVs.

      The BYD e6 is rated 300 km (186 mi). Same for the BYD-Daimler Denza.
      The extra weight obviously hurts range, but it isn’t a deal killer.

      • Otis11

        Right – so while better energy/kg is absolutely a welcome improvement, isn’t it energy/$ that is our most limiting constraint currently? Why do we not talk about that more?

        (Sorry, I typed that first comment up in a rush last night and came off a little more negative than I intended.)

        • Bob_Wallace

          Energy/$ is the limiter. If batteries were more affordable we could build a 200 mile range EV for $25 or less.

          According to Musk there is less than $100 worth of materials in a kWh of lithium-ion batteries. Get the battery price to ~$100 and a 48 kWh pack wouldn’t be much different in price than an ICE with all its support systems.

          Will Musk build the gigawatt factory? How fast will that pull down prices? We know Musk is a bright enough and careful enough person to have pulled some excellent brains together to work through all this.

          It’s going to be very interesting.

          • Otis11

            Looking forward to see it happen

            And if he needs money – Why not open up more stock? Instead of relying on outside companies to partner, create more stock and own the gigafactory outright. (I understand creating more stock will water down the value of current stock, but if balanced so that the amount of stock sold is offset by the value the gigafactory brings to the company, it should be a wash. Factor in the fact that it makes the public more invested in Tesla’s success as a company and it’s a win…)

  • Varun A Shah
  • Larry

    If it ever goes commercial, maybe it could use all the Nickel from those old NiCd batteries

  • Steve Grinwis

    So, they’ve gone from: cathode dissolves if you try to use it, to 100 cycles…. Not bad! Refine the technology a bit more, and it’ll be a serious contender.

  • andereandre

    I really hate this type of headlines.
    What is wrong with “Promising progress in Li-S battery technology” or something like that?

    • Russell

      Yes its a bit annoying to put things in perspective when there’s always headlines like that. I would also like every article referenced to a chart with all the latest tech and existing tech so people can see how it compares. No other news outlet does that, so it would be an effective point of difference.
      E.g. for batteries it is W/l W/kg (similar) $ per KWh, number of recharge cycles, round trip efficiency and the capability to scale up production. For a battery to be a breakthrough there needs to be a process to make 1 billion electric cars from it.
      It would be some effort to make the page with this info, but if each time you showed how the new potential tech *could* change things it would really help.
      You could also of course keep track of such stories over time so people can see how they played out. Li-ion was once speculative tech but it worked.

  • Will E

    the train is electric
    energy comes from energy lines above
    car is electric
    put an energy cable in the highway
    induction charging while driving.
    and a battery base load range of 200 km is suficient.
    to go anywhere.

  • JamesWimberley

    “89% of its initial charging capacity after 100 charging cycles” suggests the new technology is a serious contender, but it’s still some way from commercial readiness. EV lithium-ion batteries are supposed to be good for 300-500 deep discharge cycles before the capacity drops to 70%, but go much longer with partial discharges and top-ups. Any replacement technology has to be as least as good as the incumbent one, which is itself improving, and benefits from economies of scale and experience. That’s why plain vanilla polycrystalline pv trudges on and on, leaving challengers by the wayside.

  • MarTams

    This reeks of EESTOR!!! Are these the same group of people behind this new hype?

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