Evisceration of the LiIon

[Vladimir Vassilevsky]

I had a laptop battery which quit working. So, being a firm unbeliever
in the horror stories about LiIon, I opened it. There were 8 cylindrical
cells 18x65mm, hardwired parallel in pairs, 4 pairs in series. There was
also a charge circuit with connections to each pair, and a thermal fuse.
From 8 cells, 5 showed the infinite resistance on the meter. The
remaining 3 cells were live. I approximately charged and discharged
them, and got about 3A/h (rated: 3.6A/h each). So I made a 12V battery
of those cells and used it as the power source for the low noise
measurements.
Today one of the cells came to the infinite resistance in the process of
charging. This happened because of the membrane contact under the /+/
terminal cap. The membrane was popped by the internal pressure,
disconnecting the cell. Once it is popped, it can't be restored.
Although it was still possible to get the contact by soldering wire
directly under the cap, I decided to look what is inside the cell.
So I eviscerated the housing. That was easy to do since the housing was
made of copper (unlike NiMH batteries). Inside there was a roll (looking
similar to what you see in the electrolytic caps), saturated with
electrolyte.
As soon as the roll was exposed, the whole thing started to heat up and
soon reached about 80..90C. The electrolyte leaked out of the roll and
boiled inside the roll. There were few electric sparks between the foil
electrodes. Everything was over in about 10 minutes. No flames, no
explosions, just boiling and bad smell.
Then I unwounded the remains of the roll. The /-/ is copper foil, the
/+/ looks like aluminum, there are 3 teflon (?) layers like separators
in between. The layers are covered with carbon and other stuff.

So, as it was expected, the stories about the LiIon explosiveness are
rather exaggerated.


Vladimir Vassilevsky
DSP and Mixed Signal Design Consultant
http://www.abvolt.com

 

[Vladimir Vassilevsky]

On Sun, 15 Mar 2009 13:05:58 -0500, Vladimir Vassilevsky wrote:


You can smoke a cigarette while pumping gas a thousand times, and only be
engulfed in a ball of flame once.

Have you ever tried to ignite gasoline with a cigarette? It is more
difficult then to ignite a cigarette from the soldering iron.

Does that mean that the stories about gasoline's explosiveness are
exaggerated?

Oh yea. Socially conscious, environmentally friendly, safety first and
that kind of stuff. What happened to the explorer spirit of the heroes
of Jack London and Herman Melville?

Even if they are, does it mean that you shouldn't still be
careful around gasoline?

Well. If SLA or NiMH is shorted, it will boil and pop as well. The main
difference is that the LiIon stuff is flammable.


Vladimir Vassilevsky
DSP and Mixed Signal Design Consultant
http://www.abvolt.com

 

[Clifford Heath]

So, as it was expected, the stories about the LiIon explosiveness are
rather exaggerated.

Interesting, thanks for the report. Of course, once you'd opened
the containment, there was nothing to contain a pressure buildup
so it was to be expected that the oxidation of the Li would be
rather less spectacular than it might be.

 

[TTman]

I had a laptop battery which quit working. So, being a firm unbeliever in
the horror stories about LiIon, I opened it. There were 8 cylindrical
cells 18x65mm, hardwired parallel in pairs, 4 pairs in series. There was
also a charge circuit with connections to each pair, and a thermal fuse.
From 8 cells, 5 showed the infinite resistance on the meter. The remaining
3 cells were live. I approximately charged and discharged them, and got
about 3A/h (rated: 3.6A/h each). So I made a 12V battery of those cells
and used it as the power source for the low noise measurements.
Today one of the cells came to the infinite resistance in the process of
charging. This happened because of the membrane contact under the /+/
terminal cap. The membrane was popped by the internal pressure,
disconnecting the cell. Once it is popped, it can't be restored. Although
it was still possible to get the contact by soldering wire directly under
the cap, I decided to look what is inside the cell.
So I eviscerated the housing. That was easy to do since the housing was
made of copper (unlike NiMH batteries). Inside there was a roll (looking
similar to what you see in the electrolytic caps), saturated with
electrolyte.
As soon as the roll was exposed, the whole thing started to heat up and
soon reached about 80..90C. The electrolyte leaked out of the roll and
boiled inside the roll. There were few electric sparks between the foil
electrodes. Everything was over in about 10 minutes. No flames, no
explosions, just boiling and bad smell.
Then I unwounded the remains of the roll. The /-/ is copper foil, the /+/
looks like aluminum, there are 3 teflon (?) layers like separators in
between. The layers are covered with carbon and other stuff.

So, as it was expected, the stories about the LiIon explosiveness are
rather exaggerated.


Vladimir Vassilevsky
DSP and Mixed Signal Design Consultant
http://www.abvolt.com

Hit a lithium with a hammer and see what happens..... entirely at your OWN
risk of course. Don't blame me if you seriously injure yourself.....

 

[legg]

I had a laptop battery which quit working. So, being a firm unbeliever
in the horror stories about LiIon, I opened it. There were 8 cylindrical
cells 18x65mm, hardwired parallel in pairs, 4 pairs in series. There was
also a charge circuit with connections to each pair, and a thermal fuse.
From 8 cells, 5 showed the infinite resistance on the meter. The
remaining 3 cells were live. I approximately charged and discharged
them, and got about 3A/h (rated: 3.6A/h each). So I made a 12V battery
of those cells and used it as the power source for the low noise
measurements.
Today one of the cells came to the infinite resistance in the process of
charging. This happened because of the membrane contact under the /+/
terminal cap. The membrane was popped by the internal pressure,
disconnecting the cell. Once it is popped, it can't be restored.
Although it was still possible to get the contact by soldering wire
directly under the cap, I decided to look what is inside the cell.
So I eviscerated the housing. That was easy to do since the housing was
made of copper (unlike NiMH batteries). Inside there was a roll (looking
similar to what you see in the electrolytic caps), saturated with
electrolyte.
As soon as the roll was exposed, the whole thing started to heat up and
soon reached about 80..90C. The electrolyte leaked out of the roll and
boiled inside the roll. There were few electric sparks between the foil
electrodes. Everything was over in about 10 minutes. No flames, no
explosions, just boiling and bad smell.
Then I unwounded the remains of the roll. The /-/ is copper foil, the
/+/ looks like aluminum, there are 3 teflon (?) layers like separators
in between. The layers are covered with carbon and other stuff.

So, as it was expected, the stories about the LiIon explosiveness are
rather exaggerated.


Vladimir Vassilevsky
DSP and Mixed Signal Design Consultant
http://www.abvolt.com

There are different constructions of LiIon.

Have been recovering the paste-former perforated metal from early
prismatic cells, at various times for varied re-use. This paste will
glow red hot and burn on exposure to air in exothermic energy release,
so disassembly is best performed under water, where decomposition
still occurs, but in a less dramatic manner. Opened cells are likely
to retain their pre-fusing charge.

I store old cells, individually isolated, in a fire-proof, air-tight
metal container.

By the way, you don't want to be accidentally getting too much free
Lithium into your system, as it may have serious side-effects
......though some posters might benefit from a more controlled version
of this kind of therapy.

RL

 

[Dirk Bruere at NeoPax]

Have you ever tried to ignite gasoline with a cigarette? It is more
difficult then to ignite a cigarette from the soldering iron.


Oh yea. Socially conscious, environmentally friendly, safety first and
that kind of stuff. What happened to the explorer spirit of the heroes
of Jack London and Herman Melville?


Well. If SLA or NiMH is shorted, it will boil and pop as well. The main
difference is that the LiIon stuff is flammable.

And the burn products corrosive eg LiOH.
Don't breath it in.

--
Dirk

http://www.transcendence.me.uk/ - Transcendence UK
http://www.theconsensus.org/ - A UK political party
http://www.onetribe.me.uk/wordpress/?cat=5 - Our podcasts on weird stuff

 

[Nemo]

That's really interesting, I've never deliberately tried to dissect one
of those cells. Here's some ancillary info which may help explain why
you should be wary of Li-ions.

(1) There are different Li-ion chemistries. Some, like the Ovonics one,
are safer. In general the battery manufacturers are in an arms race to
get the best energy density though, and high energy density generally
means high short circuit current and high temperatures when shorted! I
have seen solder melt when shorting Li-ion cells (we were interested in
minimising the short circuit temperature and had a sensor attached by a
loop of soldered wire).

(2) You know all those tight charging conditions? And about Li-ion
safety IC's? (Buried in the end of Li-ion cells is a tiny PCB with a
window comparator and a dual FET, which will isolate the cell if its
voltage falls below about 2.7V or goes above about 4.2V.) If the battery
goes too far out of the 2.7 to 4.2V range, metallic lithium separates
out. Consider: if the lithium is bound to something else, and is exposed
to water, it ain't too much of a problem. To burn, it has to first be
stripped out of whatever it's in, so the reaction isn't *too*
exothermic. But if it's metallic, AND the battery gets punctured, well
now you've got problems.

(3) Battery manufacturers consider 1 million cells a day to be a small
manufacturing run. Some cells WILL get punctured. For example I've seen
one that got smashed open down a mine, when a train ran over it. So the
reputable battery manufacturers WILL NOT sell the cells without the
safety circuits.

(4) Some dodgy manufacturers save 20 cents by missing out the safety
circuit. (I recall being approached by a Chinese outfit I'd never heard
of who guaranteed to undercut our supplier. "What about the safety
circuit?" I asked. They referred back to their factory... no one even
there knew what I meant.) Now, bear in mind the stories you heard 3-4
years ago about Nokia phones exploding when charged, and Nokia
investigating and saying "these were not Nokia batteries, the users
tried to use cheap ones"... of course Nokia still got the blame in the
media.

(5) The laptop batteries that smoked in an exhibition a year or 2 ago
were a different problem. Something about pushing the energy density too
far for the state of the art, ended up with microscopic shorts between
electrodes, across small particles inside the battery.

 

[[email protected]]

I bought a used laptop about 1 year ago and bought a new spare Li-Ion
pack to go with it. The application for the laptop faded out and it
sat for 1 year. I recently found a new use for the laptop and found
that both the batteries were flat and would not take a charge.

Being a EE I thought I would try to learn something about these
batteries, so I read all I could find on line and found 1 vague
reference that recovering these flat batteries was "difficult".
Several of the references I read said they were completely
unrecoverable.

Since the built-in protect circuit prevents re-charging them when they
are flat, I painstakingly opened the plastic case the 8 18650 type
cells were in. (I don't recommend any non-EE try this). I then
attached a few short leads to the actual battery pack itself so I
could hook up a an external variable DC power source. I verified the
pack voltage was about 1 volt or less. I set my external power supply
to 1 volt and attached it to the pack. The pack acted like it was a
high internal impedance. So I only applied .1 to .2 amps and let the
pack sit. The current slowly went down and battery voltage slowly
rose. So I slowly adjusted the voltage a bit higher every 10 -20
minutes in a time consuming process. I was working on another project
at the very next workstation, so I was almost continuously monitoring
the process.

Slowly over a period of 8 hours, the battery pack voltage eventually
reached 15-16 volts. I let the pack rest overnite and then checked the
voltage the next day at 13.5 volts. I put the DC source back on and
let it sit for another day at 16 volts. I checked the impedance of the
pack and it tested good. So I glued the plastic case back on the pack
and put it in the laptop. The computer said it was at 16% and working.
I let it charge in the computer with the computer off for 8 hours. It
then indicated 90% charged. I played a DVD move for 45 minutes as a
test and it said it still had 44% of charge after 45 minutes of use.
This was similar to a test I ran when I first got the laptop.

I am now doing the same thing with the second battery pack. It appears
to be responding the same so far. I don't know how long these
batteries will last, but I just wanted to share this information.

The hardest part of the process is getting the plastic case apart in a
fashion that will allow it to be glued back together. This is so
difficult that I do not recommend this process to anyone.