The lithium does not dissapear. If we ever do 'run out' of lithium (or similar resources), then we would still be able to mine it from our own waste. The only question is how expensive the resource has to get before it becomes economical to do so.
But considering that, oh, say, batteries returned for recycling are going to be a relatively rich source of lithium, the recycling waste itself is no more viable a source than any other ore.
You can separate minerals from one another given sufficient energy inputs, but then you're getting at the issue of EROEI for the entire battery storage chain. Pretty much anything, even gold, can be extracted from seawater, given sufficient energy investment.
