In a Tesla battery pack there is only about 8 kg of lithium used - less than lead in a normal car battery. As lithium is a rather common element, it shouldn't be too difficult to mine it in the neccesary amount. Current mining capacitly is set by the comparatively low demand before electric cars.

Lithium will never be a problem. Cobalt and rare earth elements will be.

Is lithium hard to acquire? Sure, it's costly to mine, but it's not like there are shortages. Besides, it seems that Australia is a major producer of lithium.