And there some battery techs that may wipe out the Ni/Co requirements for batteries.
No one seems to mention LiS batteries which were used in the Solar powered flight tests and supposedly will be available from Sony in 2019-2020. 3 times the storage capacity of current Li batteries.
There is a another company that has some LiS prototypes, but the number of cycles looked really bad (although 80%DD)
I believe there are also some nasty physical issues as the S expands/shrinks by 70-80% on the charge/discharge cycles.
