Regarding “On the horizon” (November), about new battery technologies that could take the world beyond lithium ion: Of the four technologies you researched, I am most hopeful with regard to fluoride batteries.
But there is a technology you didn’t include that has very recently been developed to a point where it seems ready for production. That technology is lithium carbon dioxide batteries. These batteries have over seven times the energy density of lithium batteries and can go through 500 cycles without much loss of capacity. So when will we see them?
ELIZABETH JANE, Queenstown, Australia