Solid State Lithium batteries are coming along nicely
https://spectrum.ieee.org/energy/en...ithium-batteries-to-debut-this-year-in-drones
"...The battery’s energy density is about 500 watt-hours per kilogram, twice that of a conventional lithium-ion battery’s 250 Wh/kg. The downside is that it can be recharged only about 200 times, as opposed to more than 1,000 times for conventional batteries. ..."
"...The new battery design has twice the energy density of conventional lithium-ion batteries and can be recharged 23,000 times...."