By now, lithium is probably recognized as a useful material and is considered to be critical for dealing with climate change. A recent paper in Nature (vol 616, 245) discussed some of the issues. In 2018, demand for lithium was about 55,000 t/a, by 2025 it is expected to reach 150,000 – 190,000 t/a, and by 2100 it could reach 700,000 t/a. The IEA predicts that by 2030, only about half of what is required could be delivered. The production of lithium is currently complicated. Ores are roasted at 1100 degrees C, then baked in acid at 250 degrees C to leach out acid solubles. Apparently about a half a dozen chemical reactions are carried out to get rid of impurities, and the solution is evaporated to make lithium carbonate. To make a tonne of lithium salt, you need 60 MWh of electricity and 70 cubic meters of water, while the overall process, including mining, emits up to 35 t of CO2. Worse, most of the lithium occurs in basically dry areas, such as in Western Australia. The waste includes elements such as arsenic, thallium, chromium uranium and thorium. Finally, by 2030 there will be roughly 8 million t of sodium sulphate as a byproduct. This arises th4rough the lithium carbonate being made bey taking lithium sulphate and sodium carbonate. Lithium carbonate is only soluble in water at about 1% at 20 degrees C.
The need for an improved extraction process is obvious, but just because the need is obvious does not mean it will be easy. One method proposed is to find a sorbent that you pass the solutions through and only the lithium is absorbed. Ther e appears to be only one problem with this proposal: as yet we do not have such a sorbent. Is one possible? I would guess yes, but it may take some time to develop, and of course you want to be able to get the lithium out of the sorbent and reuse it. What are the prospects? It is possible to make substances like zeolites with specifically sized channels and have functional groups in them that will absorb the desired product. My guess is the zeolites are unsatisfactory because their absorbing properties come for cationic charge, which would presumably repel lithium, but there is plenty of scope to have the concept played out with something more suitable. So I would give that option a firm “maybe”.
The next suggestion is electrolysis. My concern is that the impurities noted above would coat the electrodes, while the lithium would stay in solution. It may well be somewhat more concentrated around the anode, but they will not deposit. Basically, what is being done is to electrolyse water, and coat some electrodes. Unless there is some undisclosed trick, I give this a fairly firm “dubious”.
The Nature paper suggests that one way to use the otherwise waste sodium sulphate (which is very water soluble) would be to convert it back to sodium hydroxide and sulphuric acid. No route was suggested, and while this is possible, my guess is it would be extremely expensive. Of course, the solution would have a certain amount of lithium carbonate as well.
The digging up of rocks could be avoided by passing water into the mineral bed, similar in concept to fracking. That, to me, would almost certainly work, although at what cost remains to be seen. There would still need to be good purification techniques.
Another alternative noted in the paper is not to bother purifying the lithium, but to use disordered rock salts, which are more abundant than cobalt or nickel. At this point the article seems to overlook why cobalt is used in the first place: it can form a trivalent cation as well as a divalent one. When the lithium changes oxidation state at the anode, something has to do the opposite at the cathode, AND it has to do so without a volume change. If it fails and has a volume change, the cathode will fracture after so much charging and the battery dies. The article notes these disordered rock salts require high voltage charging, at which point they become unstable. Not desirable. There are so many things that we do not know how to get around for this to work I consider it extremely doubtful.
Recycling sort of works. The batteries are shredded ( and hopefully do not catch fire because a lithium fire is almost impossible to put out), then the lot is heated to recover the metals as an alloy, while the lithium is in a slag. It is then treated like an ore. That needs a better process.
So, where does this end up? In my opinion the most likely outcome will be a different type of battery. A sodium ion battery will have unlimited sodium, but since it has yet to work we do not know what else it requires. My bet goes back to the chemistry I suggested in my first Mars novel: an aluminium chlorine battery, although prior to charging it merely contains aluminium chloride. Neither of those elements are in short supply.