Extracting lithium foil from a battery

Initially only used in fancy camera batteries, lithium is now available in AA and 9V batteries for use in things like smoke detectors and digital cameras. They are still (2002) much more expensive than regular batteries, but last a lot longer.
The great thing about disposable lithium cells is that the lithium exists in the form of a foil, not some kind of powder you can't separate. Note that this is only true of new, unused disposable lithium batteries. The reaction that powers the battery consumes and fragments the lithium, and you won't get a foil out of a used one. In fact, based on my experience disassembling a fully discharged lithium AA battery, it's not something you would want to do. Shortly after unrolling the coil (see below for more details) the thing actually spontaneously ignited in front of my eyes. Seriously, I opened it up, it started feeling warm, and seconds later the paper towel it was on burst into flames. I've never really had that happen before in quite so spontaneous a way, in my 30-odd years of taking things apart and sometimes trying to make them burn. (I picked up the paper towel from the sides, which were not burning yet, and set it on the concrete floor of the shop for safe burning out.)

I'm not really sure whether this was a unique event (it was extremely humid at the time, which may have contributed). I've never had it happen with a fresh battery, and I'm not planning to repeat the used battery experiment, except maybe to film it some time.

Anyway, back to fresh batteries. To get pure metallic lithium, all you have to do is dissemble the battery and unroll it.

Of course, this is somewhat like saying all you have to do to save the world is clip the right wire on the time bomb. Disassembling a AA lithium battery is not something to be done lightly: It can be quite dangerous. The chemicals inside will burn exposed skin and eyes, and as I can tell you from personal experience, it's entirely possible for it to catch fire completely unprovoked. Eye protection is absolutely, positively required for any experiment involving alkali metals, and you should also work in an area where things can burn themselves out harmlessly. A concrete floor (without spilled oil) is good, or I like to use a cast-iron welding table I got at an auction.
One problem is short circuits. If you short out the terminals of a lithium battery, it will heat up quite rapidly (a second or two), and can become dangerously hot. You may have read about people whose pockets caught fire when they carried these things loose with some change or keys.
The trouble is that when you use diagonal cutters to clip away the fairly tough metal casing, you'll almost certainly make contact with the positive terminal, because that's the only place you can start cutting. The key is to cut away the top as quickly as you can, removing any internal shorts you've created before it blows up in your hands.
Once you've started the cut at the top rim, removed the various disks and rings you'll find at the top, and made sure there are no shorts (as evidenced by the fact that it's not continuing to get hotter), the casing can be peeled back using diagonal cutters or some pliers, until you've exposed enough of the coiled core to pull it out of the casing. Be careful not to puncture the plastic inside, or you'll create more short circuits. If you're foolish enough to have gotten this far, be warned that from here on out, you should definitely be wearing non-flammable gloves. You do not want to touch elemental lithium with your bare hands, especially if you're nervous. (It reacts strongly with moisture, liberating hydrogen gas. On the plus side, this gas will usually not spontaneously catch fire.)
If you clip away the plastic wrap or tape holding the coil together, you can then simply unroll the thing, which will separate into several layers. One is a shiny metal foil that looks a lot like aluminum foil. It is, in fact, aluminum foil, so discard it. Another layer is a black flaky/powdery substance that smells bad. This is the electrolyte, which you should wrap in a plastic bag and discard in a fire-safe way. There are also some plastic layers that are of no interest. What you're after is the dull, soft foil that is probably dark brown by the time you see it. This is the lithium.
Depending on the humidity level, it is almost certainly oxidizing before your very eyes. On a moist midwestern night, the foil will actually stay comfortably warm, simply by the continuous reaction with water in the air. In any case, it will not last long, certainly not a whole day, in the open air.
You could try to preserve it under oil, but what's the fun in that?
Or you could throw a small patch of it into a bowl of water, but of course that would cause it to disintegrate almost instantly in a froth of bubbles, which there is small but real danger could ignite spontaneously. (The reactivity of alkali metals increases as you go down the periodic table. If you throw sodium or potassium into water, the gas most likely will ignite, but with lithium, the reaction usually isn't hot enough to light the gas. At least not in my experience: This could be your chance to make emergency room history.)

A fellow experimenter, Gill, reports his technique for extracting lithium foil intact:

Get a container of dried liquid paraffin ready.

Dismantle battery. In the process you will inevitably crush the foils thus short circuiting the battery and causing a fire. Wait until it subsides and carry on. You will only have burnt about a 50th of the Li.

Once dismantled, put the foil as quickly as possible into the liquid paraffin and separate from any remaining waxed paper strips or other battery content under liquid paraffin.

It's not as difficult as the first attempt misleads you. Don't be put off by small fires. Short circuiting the insides of the battery, thus igniting it is inevitable, but happens at the early stages when the Li is still well enough covered by battery case to run out of oxygen before burning away.

Personally, I haven't had that much problem with them catching fire from short circuits. It probably depends a lot on the brand of battery you're using.