• Mar 15th 2010 at 9:03AM
  • 9

It was more than two years ago that we first heard of a potential battery breakthrough developed by Stanford University professor Yi Cui using carbon nanowires. The bundles of nanowires that comprise the battery anode have more room to swell while absorbing lithium ions without cracking, enhancing the energy storage capacity and lifespan of the battery.

Since 2007, Cui and other researchers at Stanford have been working on new cathode materials that can help to take advantage of the properties of the nanowire anode. They have now developed a lithium sulfide electrode that, in combination with the anode, increases the energy density of the battery by a factor of four.

The new lithium sulfide material also resists the safety issues associated with high-capacity lithium ion batteries. Metallic lithium grows crystal structures during charge and discharge cycles that can pierce the separator materials between the electrodes, which can cause shorts and the thermal incidents (aka fires) that we have seen in some consumer electronics devices. The non-metallic lithium sulfide compound doesn't have this characteristic, making the new batteries safer.

The team now has to find away to make the battery last more then 40-50 charge cycles by stopping the production of poly-sulfides during charge-discharge. It will likely be quite some time before we see these types of batteries commercialized.

[Source: Nano Letters via Technology Review]

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    • 1 Second Ago
      • 5 Years Ago
      We don't have to worry, Eestor is on the way. By the way, I haven't heard much from them lately.
        • 5 Years Ago
        You're joking about Eestor, right? - But I wouldn't compare this battery with the mythical Eestor -since Stanford is quite a bit more reputable than the private speculators developing competing systems - Dr Cui's unit could be developed commercially in less than five years, if GM, Ford and the US Dept of Energy made the extra-effort to commercialize this system - kind of like the Manhattan Project, only with battery systems. And it has FOUR TIMES the capacity of present-day batteries? Awesome! This means the Tesla would go from 200 mile range to 800 mile range - if effect, making it - and all electric cars - competitive with petrol and diesel fueled vehicles (the furthest I've ever driven in one day is 732 miles - most folks would drive considerable less than that).
      • 5 Years Ago
      For those saying that most techs don't make it to market, true! However, while the odds of any one making it to market are low, when you have literally dozens, the odds of *all* of them failing are virtually nil.

      As for this -- I follow Cui's work (he's done a lot of amazing stuff), but I'm confused by his results here. Sounds like he's using a slightly modified version of the University of Waterloo cathode... but the University of Waterloo cathode was famous for having minimal polysulfide formation (at least in the short term). That's what was special about it. So I can only assume that Cui's modifications ruined it or that he built it wrong.

      The U of Waterloo approach was really clever. The cathode was based around mesoporous carbon -- carbon full of deep pits. They heated it with sulfur, causing the sulfur to wick into the pores. They then treated it with polyethylene glycol to make its outer surface hydrophobic. Polysulfides (an intermediary reaction product that is soluble and hence tends to escape) are hydrophobic as well, so they tend to stay away from the outside of the electrode and stay confined to the pits, where they can complete their reaction.

      Anyway, one thing to keep in mind with any high density battery tech: as long as the internal resistance doesn't rise too high, it's fine to lose lots of capacity early on. Let's say you get 4x energy density and you lose 20% capacity in 40-50 cycles, and it plateaus at a 50% capacity loss before stabilizing. Well, even your plateau would be twice as good as current cells. Also, 40-50 cycles of 4x density cells is as much distance traveled as 160-200 cycles of 1x density cells.
        • 5 Years Ago
        +1 meme, very well said "while the odds of any one making it to market are low, when you have literally dozens, the odds of *all* of them failing are virtually nil."

        I've said several times on this board, I don't care HOW we get off foreign oil. Let's just all do our part. Here's what you can do.
        ... Drive an electric car, or
        ... Drive a series hybrid such as the Volt, Fisker Karma, Raser Fleet Truck, etc., or
        ... Drive a flex fuel ICE - and fill up with E85 as often as you can (82% of the time to completely remove foreign oil from your fuel consumption), or
        ... Ride an electric motorcycle or bicycle 70% of the time, or
        ... Take public transportation almost all of the time

        Did I leave any out?
      • 5 Years Ago
      While this is clearly nice to see, and encouraging to read about, until developments like these show they are 100% commercializable it's not worth getting excited about.

      This development has a long way to go, with several hurdles to overcome, and then years in testing with battery firms before it ever makes it into a EV or PHEV.

      Charge cycle degradation would be the first hurdle to overcome..mass production issues would be the second.
        • 5 Years Ago
        watt-hours (wh) NOT kilowatt-hours (kwh)
        • 5 Years Ago
        Just because you won't be able to buy it next year does not mean that we shouldn't be excited about it. This is VERY exciting, as are innumerable other research topics that are still making the jump from the white-board to the bench-top.
        • 5 Years Ago
        This represents one of the possible upcoming advancements of automotive batteries predicted within 5 years from now. 2015 will bring 4x (~800 kwh/kg) with lithium sulphide and 2020 could bring 10x (~2000 kwh/kg) with lithium air.

        This IS exciting because there are many predictions that range and costs will keep BEVs down (below 10% new car sales) well past 2020.

        This IS exciting because automakers make decisions about today based on where battery technology will be in the future. This new technology proves there is still a lot of room to advance. And not some obscure challenge that is way beyond reach.
        • 5 Years Ago

        Do you know how many developments never make it to the markets? Don't mean to be skeptical, just realistic. Believe me I'd love to have a magic button to make this work today.
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