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I was surprised when I went to go buy some new rechargable batteries to see non-rechargable AA and AAA batteries advertised as containing lithium. I assumed this was wasting material that should be put into lithium-ion batteries. I can't find anyone discussing this after a few web searches, although the keywords are a bit busy as there is an active discussion happening all over about better recycling of rechargable lithium-ion batteries. I'm pretty ignorant about chemistry, is the fact that this is isn't being discussed as simple as lithium-ion batteries require a particular isotope of lithium that needs to be isolated, similar to how most uranium ore isn't useful for nuclear power and we need to isolate the isotope that is useful? And then maybe these disposable batteries are using a up a bunch of spare boring lithium?

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No. Lithium is chemically lithium, no matter what the isotope. Uranium has two isotopes, U-235 and U-238. Out of these U-235 is fissile and U-238 is fertile. Current reactors only can use U-235 so the uranium needs to be enriched since 0.7% U-235 in natural uranium isn't enough. Better reactors can utilize the U-238 too by breeding it into plutonium.

Lithium has many isotopes. Some of them can be used to create tritium (isotope of hydrogen) for future fusion reactors. However, I believe fusion is a stupid idea not only because the isotope of lithium needed for tritium creation is very rare, and also because a fusion reactor requires far more engineering than a plutonium breeder fission reactor would require. Also, uranium can be extracted from seawater and a reactor that utilizes all of it (including the U-238) won't be economically harmed by the higher cost of seawater extraction. So breeder reactors have enough fuel for at least billion years, probably even more, until the time the Sun starts to run out of fuel and ingests Earth. After that, we won't be needing any more electricity on this planet since the planet will be no more. About 20 years ago, plutonium breeder reactor seemed like the best idea for green future. Today, wind and solar power are so cheap it makes more sense to utilize these and use pumped hydropower and underground hydrogen storage for energy storage. I don't think any kind of nuclear reactor can compete with that anymore since wind and solar are today so cheap.

But about lithium usage in batteries, they depend on the chemical not the nuclear properties of lithium. So they use all of the isotopes, no need for isotope separation.

It's true that AA, AAA and 9V lithium batteries may be bit stupid since alkaline is so much cheaper and doesn't need any rare elements. If those AA, AAA or 9V lithium batteries won't be recycled it's a genuine waste of lithium. Recycling is possible, though.

Let's calculate a little bit. The global alkaline battery market is about ~10 billion USD (rough order-of-magnitude value). A single AA cell costs maybe 0.3 USD so there are 33 billion batteries sold per year. The lithium content of Energizer AA lithium cell is "less than 1 gram", let's assume it means 0.8 grams. This means if all AA cells would be lithium cells, 26400 tonnes of lithium is needed.

Lithium reserves are 16 million tonnes. So in about 600 years, with no recycling, if all AA batteries were lithium, the lithium would be consumed fully. But then the price of lithium would increase and some of the current resources will become reserves (we have 89 million tonnes of lithium resources so if all of those become reserves we have enough lithium for over 3300 years).

In reality only a very small percentage of AA batteries have lithium, a significant percentage of cells are AAA cells (that cost about the same but have far less lithium), and recycling is a possibility.

I won't say the lithium cells absolutely ruin our future green targets. In some cases such as coin cells the usage of lithium makes sense. But in AA, using lithium is in my opinion just a little bit stupid. It's expensive and it wastes lithium unless recycled. The percentage of AA cells having lithium is so small that I'm not even sure if recycling is easy, but then again if the percentage is small it means lithium waste is small, too.

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