back to article Brit boffins blow up Li-On batteries and film the melting copper

UK boffins have taken a close-up of what happens with Li-ion batteries when they get hot under the collar, and it's not pretty. As Lenovo, Boeing, Tesla, Sony and others will attest, Li-ion battery fire-safety is worth researching. However, the University College London boffins say most analysis of battery fires has focussed …

  1. Fihart

    Not in my pocket, thank you !

    ......... “we tried to simulate a range of abuse conditions, from moderate temperatures up to trying to simulate a fire. And who wouldn't love to have the chance to try and reproduce that experiment"........?

  2. Conundrum1885

    Cool

    This is really fascinating, in a "Seconds from Disaster" documentary sort of way.

    But I always wondered what happens when a LiPo decides to go into full on Chernoshima meltdown, having had one do that while charging before.

    I did have a theory a while back that some Li-ion fires are actually caused by microscopic Li-Al dendrites from the current collectors formed over hundreds of charge cycles, the early Li metal cells were prone to Li dendrites but switching to a ion only system has mitigated the threat substantially.

    It has also been linked to tin pest as the mechanisms are remarkably similar and in fact tin contamination of the Al collector might be a possible cause of spontaneous runaway.

    Incidentally this is why Li-MnO2 and Li-FeS2 can't be recharged because this happens even if the cell is recharged at 0 celsius.

    It might work once for a slightly depleted cell but you are playing with fire here and it simply isn't worth it for something that only costs £2.25 a cell in the first place.

    1. ilmari

      Re: Cool

      When overcharged or overdischarged, the li-ion cell starts dissolving its copper, and producing metallic lithium. When the dissolved copper precipitates again, there's no telling where it ends up. If a shunt forms, it might cause localized heating and set off thermal runaway. As for metallic lithium, needless to say, it's highly volatile. The damage is accumulating.

      RC Hobby people get relatively frequent battery fires, a consequence of running batteries without protection circuitry, and running batteries hard, making their base temperature already high, before builtin or evolved defects come into play.

      1. Destroy All Monsters Silver badge
        Holmes

        Re: Cool

        Don't these batteries contain small amounts of Cobalt? Is it a good idea to vaporize that stuff?

  3. Tromos
    Joke

    Could be useful.

    I'm filing a patent for a high-speed battery operated pizza oven.

  4. Conundrum1885

    Re. Could be useful

    LMAO!

    One thing I did notice is that small <300mAh LiPo cells which are questionable often exhibit a "two step" discharge profile which suggests an intermittent internal connection.

    Upon storing for a while they invariably puff up so it might be worth checking this for the folks using LiPo on models.

    I did wonder if the problem on some of these is the same as the crimp FAIL on Li-FePO4 cells made by A123, perhaps the machine they used has the same problem?

    Its a pressure crimp so if the die was slightly off centre smaller cells would be more prone to this and in fact a "partially good" cell might later fail due to electromigration of aluminium in the interconnects.

    Its also worth mentioning that I've taken apart a fair number of cells and noticed this for myself, especially on the model heli packs.

    Sometimes the crimp fails before the cell is fully open, actually falls off the Al leaving a divot in its place like a bad spot weld.

  5. A Non e-mouse Silver badge
    Happy

    And who said science was dull?

    1. This post has been deleted by its author

      1. Kevin Johnston

        or to quote Mythbusters...."it's all fun and games until someone loses an eyebrow - then it's science"

    2. Ilmarinen
      Meh

      RE: And who said science was dull?

      Well, I thought this video was very dull. No bangs, no flames; just a couple of spotty youths saying that maybe by studying batteries they could "make them safer". Yawn.

      1. Anonymous Coward
        Anonymous Coward

        Re: RE: And who said science was dull?

        > Well, I thought this video was very dull. No bangs, no flames; just a couple of spotty youths saying that maybe by studying batteries they could "make them safer". Yawn.

        Yes, surprisingly lacking in anything informative.

        So what were their conclusions exactly?

        1. Destroy All Monsters Silver badge
          Trollface

          Re: RE: And who said science was dull?

          But the random shots of passerbys to dramatic "end of the world/dioxin blowout/nuclear meltdown soon, and these people don't know it yet" music were pretty cool.

          1. Pookietoo
            Headmaster

            Re: RE: And who said science was dull?

            "passersby"

  6. Snivelling Wretch

    They're obviously worried enough about Li-ion batteries to wear safety glasses when talking to the camera.

    1. YetAnotherLocksmith Silver badge

      Yeah, there's some guy not 4 feet in front of them brandishing a lithium ion battery and video camera arrangement!

      Got to be safe.

      1. This post has been deleted by its author

        1. 2460 Something
          Thumb Up

          Love the whistle at the end :)

        2. Groaning Ninny

          Love this, particularly as youtube refuses to go any further than 1:04 for me. It's like it's scared...

  7. Anonymous Coward
    Anonymous Coward

    Hmm

    how much do I trust the word of two 14 year old kids in a white smock.....

  8. b166er

    I wonder what's in Musk's battery tomorrow?

    1. Destroy All Monsters Silver badge

      Liquid Iron Man?

  9. Conundrum1885

    It looks a bit like

    The videos of the "Hot Cat" running away.

    I wonder if the physics of the E-Cat melting are similar, nickel + hydrogen + some magic catalyst = very VERY exothermic reaction.

  10. cortland

    More energy

    More energy = more danger. I learned that *years ago* when a "dead" alkaline PP3 was short circuited by coins in my pocket. Didn't quite blister but it certainly energized ME.

    http://en.wikipedia.org/wiki/Nine-volt_battery

    The power density of batteries is slowly catching up on gunpowder. When I built (ca 1956) an electromagnetic ball-bearing launcher, this 12 year old's version of a not yet invented "railgun", in my bedroom, I could have sent them THROUGH the wall -- if I'd used a (not invented yet) LiFePO battery instead of a Lionel train transformer.

  11. beep54
    Joke

    Rick Moranis

    So this is why we haven't seen him in a while. He's been working in a lab instead!

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