I have read up on this. I think you need to because the bulk of Chinese deposits are lithium carbonate. Lithium Manganese Dioxide is easily created by adding lithium to Manganese Dioxide. Lithium Manganese Dioxide does not occur in nature that often. However the Chinese do control MgO2, but like I said there are literally dozens of different Lithium Ion battery technologies, its just that LiMgO2 is the easiest to implement which is why we see it in most smaller batteries.
I have to agree that predicting peak anything for the future based on today’s technology is a losing bet. But, one could not power a Leaf today without MnO2.