For the second time, there is no "natural price". You need to iron this kind of wishful thinking out of your head. Companies want to buy more and more lithium, so unless you've got some breakthrough that makes mining a heck of a lot cheaper the cost will keep going up and up as more and more inaccessible reserves need to be exploited. If I have a reserve that costs $4/kg to operate when the price is $5/kg and another reserve that costs $7/kg, I may open the latter if the price rises to $8/kg. But if the price drops back down to $5/kg it's unprofitable to operate.

Here's a way to articulate this that might better mesh with your mental model. The "natural price" of a commodity isn't static. If demand increases and the only way to meet demand is to use more and more expensive mining operations, then this raises the "natural price". As per the above example, the "natural price" rose to $8. It won't drop back below $8/kg unless either we find a way to make mining cheaper, or demand drops back to levels that can be satisfied by my cheaper-to-operate reserve.