I do not understand the chemistry of the Lithium ion batteries - when the battery is depleted/kaput after 10 years, is the lithium recoverable from the battery, or has it been consumed/reduced in form so that it cannot be harvested and re-used?
Lithium metal is lithium zero. Since Li is on the left side of the periodic chart, it transports electrons to form Li+1 quite easily, hence its application in batteries. Recharging the battery means using electricity to restore the energy rich lithium metal. There is no natural source of lithium metal. The ore is Li+1 that can be refined into lithium metal and the battery.
At the end of the life cycle, the spent battery would have to be re-refined into a new battery, but in theory it could be done. The big advantage to lithium over other stuff on the left side of the periodic chart is that it is the lightest of these easily reduced metals (upper left of the periodic chart). A sodium battery would be much heavier for the same electrical load.