The current rate of mining lithium is 100,000 metric tons. The amount of lithium needed to replace all internal combustion engines is 17,712,640 metric tons. So the number of years to mine enough lithium to replace all internal combustion engines is 177 years (17,712,640 metric tons divided...
You can't simply calculate how many electric vehicles (EV) batteries are needed for the worldwide fleet to replace internal combustion engines. First of all there is no exact number of internal combustion engines in the world. Secondly there is variability in the battery size of EV batteries...