Freezing Lithium-ion -- calling all chemists

[widman]

My question isn't the typical "will this work?" I've done it and it does. My question is:
What does freezing lithium ion batteries do to cause them to refresh or begin working again after they are deader the proverbial doorknob?

By the time I was able to get and install the new plug in my Dell notebook, my 5 year old battery would not charge at all, while a second one did. I threw he dead one in the freezer for a week, wrapped in plastic. Thawed it for a day and charged it. I now have 45 min per charge. Not fantastic, but not bad.

The question is why?

 

[XS650]

I'm clueless, but thanks for the tip.

 

[HTSS_TR]

Originally Posted By: widman
My question isn't the typical "will this work?" I've done it and it does. My question is:
What does freezing lithium ion batteries do to cause them to refresh or begin working again after they are deader the proverbial doorknob?

By the time I was able to get and install the new plug in my Dell notebook, my 5 year old battery would not charge at all, while a second one did. I threw the dead one in the freezer for a week, wrapped in plastic. Thawed it for a day and charged it. I now have 45 min per charge. Not fantastic, but not bad.

The question is why?


I have no idea why, thanks for the tip. I'm going to try it since I have a dead battery too.

 

[440Magnum]

I don't actually know the process, but here's a SWAG:

Rechargeable batteries usually get to the point where they won't take or hold a charge because an inert byproduct builds up on the interface between plates and electrolyte (in the case of lead-acid batteries, its sulphates). My wild guess is that freezing the battery forms ice crystals in at least some component of the electrolyte, and that in turn cracks or pierces whatever inert material is killing the battery, exposing fresh plate material to electrolyte. It may not even be freezing- it may just be that the cold deforms the internal parts of the battery enough that cracks form in the inert buildup.

Or it may be something else entirely.

 

[Y_K]

You could also try this with hard drive. Long cable and don't freeze it as long. Temporarily corrects thermal deviation, a lot of times enough to get the valuable data off of it into back-up. As for the battery, it has a deep-cycle/reset effect forcing the changes of physical state in both directions, in short. As a matter of fact, if you have a spare one and don't use it you will prolong its life if you put in a fridge at around 0 C. No freezer in the case of good battery!

 

[Y_K]

Originally Posted By: 440Magnum
Rechargeable batteries usually get to the point where they won't take or hold a charge because an inert byproduct builds up on the interface between plates and electrolyte (in the case of lead-acid batteries, its sulphates).
Yes, it's a deposit build up in the electrolyte that inhibits intercalation. Different electrode material makes electrochemistry a little different.
In any event, freezers go to -18C while electrolyte freezes at around -40C due to cryoscopic effect. So, you won't [probably] totally freeze the battery. And sometimes you can revive it for only few minutes, so be quick.

 

[widman]

I wonder if it would have been better if I had a chest freezer? I just have the one in the refrigerator, but it worked. I had read opinions on the internet about times and whether or not it would work. I figured that since it was totally dead, I had nothing to lose.

I've done the hard drive trick successfully a couple of times, and unsuccessfully a couple. I figure that reduces the clearance in the bearings enough to get it going. Once it was a freeze and a twist on the noisy startup.

 

[JHZR2]

Originally Posted By: Y_K
Yes, it's a deposit build up in the electrolyte that inhibits intercalation. Different electrode material makes electrochemistry a little different.
In any event, freezers go to -18C while electrolyte freezes at around -40C due to cryoscopic effect. So, you won't [probably] totally freeze the battery. And sometimes you can revive it for only few minutes, so be quick.


Agree, the so-called "SEI" layer.

Note that Li-ion batteries of standard graphite anode chemistry will not accept a charge below approximately freezing.

 

[Colt45ws]

Im testing this on a Asus EeePC. Last full capacity is listed as 8100mAh. Design capacity is 8700mAh. I drained it to about 25% and froze it. We'll see what it comes back up to...

 

[JHZR2]

just be careful, charging frozen batteries can plate lithium, cause an internal short, and start a fire.

 

[Colt45ws]

I let it warm on top of my tower before I charged it.
It didnt make a difference, though. Might be too smart and 'remember' that it only can take 8100 mAh so it stops there like a gas pump.
Ill note this though for when its on its death bed.

 

[brianl703]

Originally Posted By: JHZR2

Note that Li-ion batteries of standard graphite anode chemistry will not accept a charge below approximately freezing.


No they will not, and when I was using my laptop in the car last winter and I plugged it in (and turned it on), the charge indicator light was blinking until the laptop warmed up enough for the battery to take a charge. I believe there is a temperature sensor in the battery and that is how it knew it could not charge.

 

[widman]

My only low temperature problems in various computers have been frozen dots on the screen. In real cold weather the screen starts out looking like a map of the world with splotches. As it warms up enough the splotches change to dots and eventually go away if it gets warm enough.

 

[FalconFour]

I'm no chemist, but I'm a pretty big electronics and EV (electric vehicle) geek. Since lithium batteries are the big boom in the industry today (eh... and yeah, I realize the site I'm on

), it's of particular interest to get a bump and some new information. This topic came up for two separate Google searches regarding lithium battery freezing effects, so it seems to be a popular thread for this subject. Most other results are people asking if it'll hurt their phone/laptop. >.< Not exactly...

So, here's what I've got. I work in PC repair, and the electronics side of computers often ends up in my work - like the Sony VGN-NR240E I inherited after an upgrade to new hardware. The user had *NEVER* used the laptop on battery - it sat on a desk fully charged for its whole life. Terrible for a lithium battery to stay fully charged forever - and it showed. The laptop had about 10 seconds of battery life before crashing off. Under the hood, I'm sure at least one cell pair is super-weak and buckled under the 3.0V level immediately.

So we've got a severe case of capacity lock. The battery is charged, but it's so weak, it could only release it in tiny, tiny amounts. I'd wager a guess that the separator material between anode and cathode (a somewhat hot area of innovation in today's lithium batteries) became clogged with decayed material over the time it's sat at full charge.

After stumbling across this concept of freezing a laptop battery, I tried it out. I put my phone in the freezer with GSAM Battery Monitor showing me instant current and delayed voltage levels. Playing with this setup showed me that low temps dramatically slow the battery, but seems to improve the battery's performance once it warms back up. Voltage at low temps would be very low even with no load - so it seems to affect the resting state of the cell.

The results with the laptop battery have been even more dramatic. I've frozen/thawed that battery about 3 times now, and ran it in a cycle of discharges/recharges - running it until it shut itself off, then immediately plugging it in and watching the wattage (using a Kill-A-Watt) until the charge rate dropped below 10W. Most of the charging was being done in the 5W-2W range. It'd spike to 21W for a few seconds at first, then fall through 18... 14... 12... and when it hit 9.9W, I unplugged it and immediately turned it back on. After roughly 20 of these cycles (each lasting about 1-3 minutes), after a thaw, it jumped by a huge leap - with the computer in a customized low power mode, it ran for almost 20 minutes, with the previous cycle only lasting about 4. The following charge stuck around 21W for almost 5 minutes, then over 20 more minutes above 15 watts.

My guess is that though the electrolyte itself doesn't freeze until -40C, other components in the cell change composition - hence, the significant voltage and performance drop while cold. Like cold syrup becoming thick, the flow of ions through the thickened chemistry probably started "cleaning" the collected gunk off the layers they were being forced through. Whether or not the "cleaning" ended up taking useful parts with it (hence, this "improvement" is only remporary)... that's what I'm still finding out. And like I said, not a chemist, just a good idea of lithium battery construction and performance - though I'm not sure if anything about viscosity and "cleaning" is correct.

At any rate, there's definitely something about freezing these things that they seem to like - at least, as a maintenance routine. Seems like I should drive my LEAF out to the snow some day to give the battery a good chill