Firms are exploring sodium batteries as an alternative to lithium

They power tiny phones and two-tonne electric cars. They form the guts of a growing number of grid-storage systems that smooth the flow of electricity from wind and solar power stations. Without them, the electrification needed to avoid the worst effects of global warming would be unimaginable. And in 2019 they earned three of their pioneers a Nobel prize.

But lithium-ion (Li-ion) batteries have downsides. Lithium is scarce, for one. And the best Li-ion batteries, those with layered-oxide cathodes, also require cobalt and nickel. These metals are scarce, too—and cobalt is also problematic because a lot of it is mined in the Democratic Republic of Congo, where working conditions leave much to be desired. A second sort of Li-ion battery, a so-called polyanionic design that uses lithium iron phosphate (LFP), does not need nickel or cobalt. But such batteries cannot store as much energy per kilogram as layered-oxide ones.