Why do lithium batteries swell ?

[cosmicray]

My mom and I both own older Apple laptops, which have removable batteries. Both laptops, and a total of 4 batteries (one each factory original and 3rd party replacement) have all swelled up to make them not possible (or very difficult) to insert in the laptop. One laptop, and one or two batteries, I might understand, but all of them ?

I understand there is some danger here of the batteries combusting, but is this worthy of a tear-down to see what is actually happening inside ? I have since retired my laptop, but I still have it here. Moms is about to be retired.

First picture has an original pack on the left, and a replacement on the right. Second pic has the original on top.

Edit: the battery types are Lithium Ion, Apple part A1185, 10.8V, 55 Wh

[German_EE]

DO NOT open up a Lithium battery pack that has started to swell, you risk things like fire and/or chemical burns if things go wrong (and they could go wrong very quickly). Either return the batteries to Apple or take them to your local council waste disposal facility then buy new battery packs.

[Fraser]

As stated, do not puncture the pack, the gas is really dangerous if inhaled.

[Terabyte2007]

Lithium Ion batteries will swell due to excessive heat, over-charging and etc. When the battery is in a swollen state they are exceptionally dangerous or hazardous. Quickly dispose of the battery properly by taking it to a recycling center. To prevent future swells, charge according to manufacturers recommendations, avoid excessive heat on the underside of the laptop and unplug the charger once fully charged. These are a few items that can help manage this condition.

A teardown would not be advisable.

[codeboy2k]

Overheating, over-charging generally causes the expansion you see. It could also be caused by high-current draw.

The reason for the expansion is the cathode.  The cathode of a Li-ion  battery like you have there is made of LiCoO₂ I think.. , Lithium-Cobalt-Oxygen.  During charging and during high current discharge, lithium atoms move in and out of the cathode. When lithium atoms migrate out of the cathode, the cathode undergoes expansion.  Also, the oxygen bond to cobalt is weak, so the O₂ is breaking away from the cobalt.  So you have cathode expansion and increasing oxygen. This causes the battery package to balloon up.  Now you have free (unbound) lithium ions and free oxygen ions and probably some O₂ molecules there too, which is why you are being advised to NOT open it up and do a teardown, ever.  Just watch a youtube video of lithium/oxygen reactions to know why.  It has the potential to literally explode in your hands .

The other battery technology that is popular, LiFePO₄, Lithium Iron Phospate, is far safer because the cathode, being made of LiFePO₄, does not expand as lithium migrates out, and it does not release oxygen as easily as LiCoO₂ cathodes do.   

If we haven't already, we should really move completely over to LiFePO₄ batteries for consumer use.

[n45048]

A normal Lithium Ion pack from a reputable manufacturer should never swell. Swelling indicates a fault or problem with a pack, more commonly seen with cheap Asian after-market batteries (although there are well known cases of some big brands suffering issues).

Dispose of your faulty batteries in accordance with your local dangerous goods disposal guidelines and order new ones.

[cosmicray]

A normal Lithium Ion pack from a reputable manufacturer should never swell. Swelling indicates a fault or problem with a pack, more commonly seen with cheap Asian after-market batteries (although there are well known cases of some big brands suffering issues).

Dispose of your faulty batteries in accordance with your local dangerous goods disposal guidelines and order new ones.

As I said, one laptop is retired, and the other about to be retired. Battery replacement will not be happening. The various packs will be disposed of properly.

The Apple one was constructed is such a way to allow some room for the battery to expand (2nd picture shows this). The 3rd party pack is glued shut, all the way around, and is likely more dangerous for this reason. It still seems odd that all 4 packs had the same behavior.

[IanB]

I think what Halon said, that swelling of lithium battery packs is a symptom of poor quality control in manufacturing, or a manufacturing defect.

That said, I have read that such swelling tends to occur as batteries become discharged (or over discharged). The same sources say that fully charging such batteries will cause the swelling to reverse.

I do recall that Apple had issues with swelling batteries at one point and they had to recall and replace the affected products.

[CatalinaWOW]

In the RC world these swollen batteries are referred to as "puffed".  As stated the causes include poor initial quality, overcharging, over current on discharge and heat.  In my experience they all do it eventually.  It is an end of life phenomena for this technology, though the time to that end varies widely.

I would also put the hazard from these batteries in perspective.  Although the contents are not good for you, and the potential for a violent combustion event is there, they are not more hazardous than many other things we deal with.  I have punctured many with no particular response.  Think of it as more like a container of gasoline than like a container of nitroglycerin.  There is real hazard there, but with proper care a very low likelihood of having a problem. 

[Fraser]

If the posting on the candlepower forum is to be believed, the gas from a failed Lithium battery is anything but safe. Battery Chemistry may influence the gas produced but I wouldn't care to find out the hard way !

http://www.candlepowerforums.com/vb/showthread.php?141137-Inhaled-vapors-from-battery

and

http://www.rcgroups.com/forums/showthread.php?t=1142861

Aurora

[CatalinaWOW]

I am not saying they are not dangerous.  Perhaps you are under rating the danger of a container of gasoline.

The point is that they do have hazards, and those hazards can be controlled.  Respect is called for, not fear.  One good thing about this technology is that it is relatively unfamiliar, and people are more conscious of evaluating the hazard.  Gasoline (or petrol) has been in wide and common use for so long that many treat it with little regard for the potential hazard. 

In one sense, the application in laptop batteries is one of the most hazardous uses of the Li-Ion technology.  It causes a very high number of people to be exposed, and more importantly, most of the group is mostly unaware of the hazard and of appropriate precautions.  These batteries are much easier to puncture than the traditional styles as they are merely a foil pouch.  The warning against puncture is in relatively small print molded into the outer package.  Not easy to read or obvious.  I suspect many of these are crushed or punctured when they are tossed into the local refuse bin for disposal.

[cosmicray]

Of the two packs I have here, both show no charge (on the built-in indicator lights). There may be other hazards, but from a charge perspective they are inert.

[helius]

LiCoO2 cells can be abused a lot without exploding. The smoke is coming from the electrolyte, which is flammable and toxic. But fears of spontaneous combustion are overdone.