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Making Safer Lithium-Ion Batteries 77

Posted by timothy
from the for-some-values-of-safe dept.
itwbennett writes "Exploding iPhones may be a thing of the past. Researchers at Taiwan's Industrial Technology Research Institute have developed a new polymer, STOBA (that's self-terminated oligomers with hyper-branched architecture to you and me), that is added to the cathode material inside a lithium-ion battery to keep them from overheating. 'Fires or explosions in these batteries are caused by short circuits,' said Wu Hung-chun, a researcher at ITRI, explaining that even minor mishandling such as dropping the handset could result in damage causing a short circuit. 'The technology is ready for lithium-ion batteries used in electronic devices, mobile phones, laptops,' said Wu. And ITRI has started testing STOBA on electric car batteries."
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Making Safer Lithium-Ion Batteries

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  • by Anonymous Coward

    A few years ago, you could crack open the older Lithium batteries and extract a ribbon of pure Lithium, which of course was fun to douse in water and other stuff to make explosions and other shenanigans. I don't necessarily want safe.
    I also want the old liquid mercury thermostats and thermometers... mercury is fun to play with as long as you don't eat it.

    • by thomasdz (178114) on Thursday September 24, 2009 @07:50PM (#29535193)

      From the wikipedia article on "Lithium": . Lithium batteries are not to be confused with lithium-ion batteries, which are high energy-density rechargeable batteries.
      So I'm thinking it was the old non-Lithium-ion batteries that you could get ribbons of Lithium metal from. TFA is discussion the -ion variant battery.

    • by lysergic.acid (845423) on Thursday September 24, 2009 @11:03PM (#29536311) Homepage

      You can buy pure lithium from chemical supply shops. Most people buy batteries to use as batteries. And you can experiment with potentially dangerous compounds and still be safe about it. The danger isn't the fun part. If danger is what you're after then go play Russian Roulette or go streaking across a busy freeway. Having your electronics ruined by a defective battery is neither fun nor entertaining. And the normal risk of it happening is too low to be exciting even if you are looking for danger.

      Also, elemental mercury ingested (or injected intravenously) is normally not that dangerous except in cases of chronic exposure, as only 0.01% is actually absorbed by your gastrointestinal tract. It's inhalation of mercury vapors that is dangerous as even small quantities inhaled can cause acute toxicity. But even without experiencing acute mercury poisoning, its cumulative nature can still cause subtle negative health effects (such as higher chances of having children with birth defects in the case of women).

    • I bet you ate a lot of leaded paint in school too, right?

  • "drop phone watch it overheat" is the latter-day version of the halt and catch fire [wikipedia.org] "instruction" of days gone by.

  • by agorist_apostle (1491899) on Thursday September 24, 2009 @08:07PM (#29535335)
    We looked at using these kinds of batteries for an engineering applicant for a client, so one of our engineers got a sample package of different sizes and shapes of batteries along with a handy CD of what you could and could not do with them. Unfortunately, the application involved possibly putting a battery on the end of an armature to power a light, something the disc explicitly warned against NOT doing -- it came with a nice set of exploding battery clips. Our client saw those and promptly refused to carry a cell phone in any piece of clothing attached to his body from there on it. I think his laptop no longer ever rested on his lap, either...
  • Step 1 (Score:3, Interesting)

    by sexconker (1179573) on Thursday September 24, 2009 @08:12PM (#29535373)

    Step 1: Stop manufacturing them in China

    Nearly all Li-Ion battery failures (going out with a boom, pop, or fizzle) are a result of inferior materials being substituted in the manufacturing process.

    Li-Ion battery cells (the individual cells containing your delicious electrons - millions in a single manufactured cell, several of those in a single packaged battery) are expected to pop.

    Over-charge them? Pop.
    Drain them too fast? Pop.
    Result? Slightly diminished capacity.
    Over time, the capacity gets lower and lower.

    The trick is they're isolated, and you don't get enough of them popping at once to cause a noticeable failure (flame, explosion, etc.).

    But when you have shitty charging circuitry, shitty components measuring and regulating the current and voltage, and shitty material (like fucking paper) inside the thing, yeah, shit's gonna go up in flames.

    Ni-MH is the superior fucking choice. But the self-discharge rate is too high for the plebes to accept. They've got ones that sacrifice capacity for a lower self-discharge rate (such as Sanyo's Eneloop design), but Li-Ion is firmly entrenched, unfortunately.

    • Re:Step 1 (Score:5, Informative)

      by Anonymous Coward on Thursday September 24, 2009 @08:35PM (#29535517)

      it's not just discharge rate. it's pure energy density.

      ni-hm just can't store as much energy compared to lithium ion for the same size. The new hybrid Ni-HM probably has a far lower discharge then lithium-ion but that still doesn't solve the problem of lack of energy capacity. People want things to run long on a single charge (like laptops lasting 2 hours vs laptops lasting 4 hours). Most low drain devices where battery energy discharge would matter generally aren't on the radar for most people since charging within a few weeks span is simple compared to charging every few hours which is annoying and impractical.

    • by cdrguru (88047)

      But if they weren't made in China, they would cost twice as much. That is a non-starter.

      Sorry, but everything has to be as cheap as possible, even if it only lasts a short while. Built-in obsolesence is being replaced by built-in short life.

      • Re: (Score:2, Interesting)

        by Hal_Porter (817932)

        But if they weren't made in China, they would cost twice as much. That is a non-starter.

        That's not true. There are countries that have the Rule of Law and are not much more expensive than China. Taiwan or Malaysia being my favorites.

        Plus a lot of electronics is not labor intensive if you do it right. Most of the labor intensiveness comes from people that make stuff badly so that the failure rate is high and then employ huge numbers of people to screen out the failures. Still if you get it right and source the components from people you can sue or at least not pay if they send you bad component

      • Re: (Score:3, Funny)

        by LordSnooty (853791)

        Built-in obsolesence is being replaced by built-in short life.

        Is that the "short life" of the battery, or the "short life" of the person who had the battery explode in their pocket?

    • Re: (Score:2, Insightful)

      by Anonymous Coward

      But when you have shitty charging circuitry, shitty components measuring and regulating the current and voltage, and shitty material (like fucking paper) inside the thing, yeah, shit's gonna go up in flames.

      Go talk to any real life RC community or online forum and you'll hear stories of li-ion and lipo failures from people who use quality chargers and cells. I know more than a few guys who store/charge/transport their lithium batteries in a box full of sand, just in case.

    • Re:Step 1 (Score:5, Informative)

      by russotto (537200) on Thursday September 24, 2009 @11:17PM (#29536401) Journal

      Ni-MH is the superior fucking choice. But the self-discharge rate is too high for the plebes to accept. They've got ones that sacrifice capacity for a lower self-discharge rate (such as Sanyo's Eneloop design), but Li-Ion is firmly entrenched, unfortunately.

      Yeah, NiMH is way superior to lithium ion. Well, except the memory effect, self discharge rate (near 0 for lithium ion, high for NiMH), the energy density (higher for ordinary LiIon, much higher for LiPo), charging efficiency (~70% for NiMH, ~95% for LiIon), and power density. Except for all that, NiMH is way better than LiIon.

      • Re:Step 1 (Score:5, Interesting)

        by Seakip18 (1106315) on Friday September 25, 2009 @12:26AM (#29536719) Journal

        Actually, you're thinking of NiCad [wikipedia.org], which does suffer from memory effect and actually has a lower ampHr/kg ratio.

        NiMH have no memory effect and can now come in a low-discharge (15% a YEAR) variant. They're pretty nice actually since they are several times cheaper than the equivalent li-ion. The Li-Ion/Li-Poly's come in handy since their ampHr/kg is much higher and therefore can fit in tiny spots when scaled against the larger Ni-MH. Nasty stuff to not charge a liion though.

        • Re: (Score:3, Interesting)

          by LionMage (318500)

          I know there are plenty of sites that claim that NiMH doesn't have a memory effect, but some manufacturers apparently claim otherwise in their data sheets. I found this discussion [electronicspoint.com] initiated by a man who was testing some Sanyo NiMH batteries; the Sanyo data sheet definitely did claim they had a memory effect, and his tests confirmed this. The effect is small but apparently measurable, and apparently also easy to undo with a normal discharge cycle.

      • Re: (Score:2, Insightful)

        by sexconker (1179573)

        You have confused Ni-MH and Ni-Cad.

    • Re: (Score:2, Interesting)

      by mhajicek (1582795)
      Try LiFe-Po batteries. Same energy density as Li-ion, but they survive an order of magnitude more charge cycles.
      • If the charging circuitry and materials are up to snuff.

        New shit is always great.
        Then they outsource to China.
        Then they substitute shitty materials.

        Then the product is barely any better than the last generation.

        There are no "charge cycles" for Lithium based rechargeables. All charging is based on the individual cells, and any "charge cycle" is based on the average of all cells. Cells get irreparably destroyed if completely drained or overcharged, and lose capacity over time. All three of these effects ca

  • by wizardforce (1005805) on Thursday September 24, 2009 @08:13PM (#29535385) Journal

    Apparently the polymer (as far as I can tell) undergoes a cross-linking reaction that acts to slow the movement of Lithium ions following puncture of the battery thus keeping the reaction relatively under control.

    http://www.itri.org.tw/eng/Research/Focus-Area/focus-sub-area-category.asp?RootNodeId=0301&NodeId=03013&FieldCD=03200 [itri.org.tw]

  • by BlueParrot (965239) on Thursday September 24, 2009 @08:28PM (#29535469)

    I'll post this preemptively since usually when battery fires are discussed some people insist this is unavoidable if you want a high energy density, but this is not true. Whether batteries can fail catastrophically or not is mainly down to two things:

    a)Whether the energy released when a cell fails is sufficient to cause nearby fails to fail, thereby causing a cascade of failed cells.

    b)Whether the materials the battery is made of can react violently with materials it is likely to come into contact with when it does fail.

    For traditional Lithium ion batteries the answer to both these questions is yes. The temperature necessary to cause a cell to fail is easily within the range of what is generated when a nearby cell fails. Furthermore the lithium batteries and their electrolyte burn quite well upon contact with air, adding even more energy to the reaction.

    There's however no principal reason why this has to be the case. As an example if the heat capacity and conductivity of the battery is good enough it is possible to design batteries so that the failure of one cell won't heat nearby cells enough to cause them to fail. Different chemistries also have different activation energies, as an example lithium iron phosphate batteries are much safer for this reason. It is also quite plausible that one might be able to create a battery from a chemistry that doesn't react violently with oxygen.

    Many batteries that use a water-based electrolytes qualify for both these criteria. Water has a high heat capacity and doesn't burn in oxygen. Unfortunately such batteries have other drawbacks. In particular while water itself won't burn it is susceptible to electrolysis at typical battery voltages, producing flammable hydrogen.

    • Re: (Score:3, Funny)

      by Tumbleweed (3706)

      I'll post this preemptively since usually when battery fires are discussed some people insist this is unavoidable if you want a high energy density

      Too late. You posted emptively.

  • Ugh, exploding iPhones again... And yet another misunderstanding about what's going on.

    iPhones do not use lithium ion batteries. They use lithium polymer batteries.

  • by Hollovoid (942476) <sean.plantz@gmail.com> on Thursday September 24, 2009 @09:02PM (#29535651)
    The additive is usually in the separator that keeps the lithium and cathode apart (which you want to do). When the battery overheats the separator breaks down and disables the battery, this has been used where I work for over 20+ years, and is in no way new tech. Putting the same thing in the cathode is like putting a guard rail on the very edge of a cliff instead of 15-20 ft from a cliff, it may stop small shorts that slowly develop in the battery, but a major short, or hole in the separator will melt down and become quite dangerous before the cathode is even involved. Plus, how hot before this effect happens? Cathode is heat treated at over 650F, I sure hope it doesnt take that much to trigger this new substance.
  • This problem should be irrelevant soon with the lithium polymer batteries. The explosions are caused by the leaking organic solvents necessary for lithium ion transport. In lithium polymer batters, the ions move along solid ethylene glycol polymers and do not require any solvents. So, basically lithium polymer batteries are the greatest things ever, except we can't manufacture them cheaply yet.
    • by razathorn (151590)

      Unfortunately, they go up like a road flare when damaged, overcharged, or overdischarged (generally they just puff up, but extreme over discharge or charge will cause them to go off). A good short will do it too.

  • by razathorn (151590) on Thursday September 24, 2009 @09:33PM (#29535831)

    In the rc car world, the two major types of batteries in use are lipo (lithium polymer) and nimh. Nimh has less energy density, self discharge, and requires some rest after discharge still to retain full capacity when charged. I run nimh due to reasons I won't go into, but I have my eye on lifepo4, or lithium iron phosphate. They are not only more robust than traditional li cells, they go off in much the same fashion as the batteries mentioned in the article. The disadvantage to them, and why they aren't 'the thing' in rc cars is that they have a voltage disadvantage. Given the strict regulation of motors in spec class racing, a voltage disadvantage is a huge issue. In other applications, where you could pick whatever voltage and number of cells to use, these batteries are awesome. In rc, their voltage makes you pick arranging them in series at a voltage level that is a disadvantage or adding another cell and making yourself have a huge advantage -- ie, their acceptance isn't based on technical merit but existing standards in racing.

    • Can't you step up the voltage with a small transformer for RC use? Wind your own for performance - it's an exercise in designing the right laminated iron core and counting the number of winds in a couple of coils. Bound to be something you can do to get the voltage up. Hmmm... weight...
      • by Big Boss (7354)

        Transformers don't work with DC. He would have to build a full on switching power supply. Those can be made lightly, but it's expensive to build one that can push the kinds of current that a lipo battery can produce.

      • by razathorn (151590)

        Because it's not AC -- it's DC. There's already voltage stepping in the ESC that provides a lower (6 volts) voltage DC to the radio, servo, etc, but at a much lower current requirement. The drive motors operate, at times, at 120 amps @ 7.2 volts or more, especially in the larger classes such as 1/8 electric. We're talking 800 - 2000 watts. Good luck :)

    • Cost and the fact that lipos are entrenched now with chargers everywhere. Classic first to market issues - the first product kind of sucks but gets an install base and the later ones have trouble making it in. Search lithium ion or lithium polymer battery charger IC at Mouser and you'll get a thousand hits. No where near that for lithium iron.

      Oh and you can't step up with the transformer because they're DC until you get to the speed controller and after that they're PWM 'alternating' (kind of) and only w

      • by razathorn (151590)

        Cost and the fact that lipos are entrenched now with chargers everywhere. Classic first to market issues - the first product kind of sucks but gets an install base and the later ones have trouble making it in.

        But that's for RC. What about phones and laptops? The switch from nicd to nimh to li wasn't that hard for them. They make new models all the time with whatever charger and battery they want. It's not like they are focusing on backwards compatibility with laptop batteries or have to contend with people saying "well, I've got 5 of these dell nimh batteries for this old laptop, I won't buy this new laptop with 5 times my old laptop's battery life because I'd be wasting these old nimh batteries" -- every la

    • by cffrost (885375)

      [...] reasons I won't go into [...]

      Nerd cocktease.

  • "And ITRI has started testing STOBA on electric car batteries." Is there such a thing as a NON-electric car battery? :-)

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