Late to the electric vehicle race, Stellantis CEO Carlos Tavares bounded onstage Thursday at the Consumer Electronics Show, the biggest tech event of the year, and boasted: In 2026, he said, Stellantis would produce a sleek new electric version of the popular Ram pickup truck. Among other bells and whistles, a breakthrough solid-state lithium-metal battery would power the electric Ram, delivering 30% greater energy density than today’s conventional batteries—enough to take the truck more than 500 miles on a charge.

But the battery Tavares described, developed by Factorial Energy, a startup based in Woburn, Mass., is not likely to be ready by then. In November, Factorial briefed me on its development of an EV-size 40 ampere-hour battery that was delivering fewer than half the 800 cycles of charging lifetime that automakers demand. So I was surprised Friday when Factorial announced that it had just delivered a 100Ah battery to Stellantis and was starting the process of commercial qualification, an exacting industry regimen that usually takes four years. Stellantis declined to comment. But in an interview, Alex Yu, Factorial co-founder and chief technology officer, agreed that 2026 seemed like an aggressive timeline. “It’s very bold,” he said.

Most major automakers are in the same situation as Stellantis: General Motors, Ford, Volkswagen, BMW and others have showered next-generation silicon and lithium-metal battery startups with cash, trumpeting plans to use the batteries to deliver cheaper EVs with greater driving range by around the middle of the decade. GM has suggested it will use a lithium-metal battery made by SES; VW has said it will use a lithium-metal battery developed by QuantumScape. But few of the battery startups seem likely to reach commercial-scale production any time soon. That will leave the EV makers with almost no alternative to conventional lithium-ion batteries at least through the end of the decade. Because solid state technology is so new and no one has manufactured solid electrolyte at large scale, most experts believe the type of lithium-metal batteries Factorial is developing, for instance, won’t be ready for mass production until the 2030s.