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.