Lithium Ion battery inventors have won Nobel in Chemistry today.
Before Lithium ion we used Nickel Cadmium batteries as rechargeable ones. Those were heavy and wouldn't have been able to fly a drone. Li-Ion made that possible.
Interestingly Li-ion battery basically is Li Cobalt battery. Cobalt in needed in equal amount and more expensive than Lithium, a rare earth material.
Lithium right now is produced in large quantities and price has fallen drastically. Main producer is China. There is no shortage of Li for batteries.