T HE ONLY thing that can accelerate as fast as an electric car is the price of the most expensive metal in its batteries. Once a niche input used to strengthen turbine blades, cobalt’s value has soared since it started to feature in modern electronics. Most phones need a few grams’ worth, and every car requires 5-10kg. That adds up. Many business models are based on ample reservoirs of cobalt that experts warn do not exist.

Soaring demand for a commodity is usually met by vaulting investment to ensure supply. Cobalt’s case is somewhat different. Nearly all of it is obtained as a by-product of mining nickel and copper. Even the sharp rise in cobalt’s price thus far has not been enough to justify fresh investment in digging more nickel and copper out of the ground. Worse, most of it is in the Democratic Republic of Congo, where neat models of supply and demand count for little.

Most incremental demand for cobalt comes from carmakers, which have invested around $100bn in electric-vehicle ( EV ) technology. According to one estimate, by 2030 at least as much of the stuff will be needed for transport alone as was mined in 2017. America has designated it a “critical mineral”.

The expected demand spike assumes both a rapid rise in EV s, which is likely, but also continued dependence of batteries on cobalt, which is less certain. Battery technology is evolving; some need less or no cobalt. Tesla, an electric carmaker, is among those saying it is “aiming to achieve close to zero usage of cobalt”, helping derail a rally in the metal’s price this year (see chart).