QuantumScape Corp., an electric-vehicle-battery startup, soared as much as 12% in late trading after saying it cleared a key hurdle in the development of its technology. The company, which is attempting to pioneer solid-state lithium-metal batteries for electric vehicles, said it was able to produce multilayer battery cells, a crucial stumbling block in taking the technology from the lab to the real world.

“While there is still a lot of work to be done and we could encounter new challenges as we increase our layer count, this is an incredibly important result, and we are excited to have this so early in the year,” Chief Executive Officer Jagdeep Singh said in a letter to investors that was part of the company’s first quarterly financial report.

The company is one of several startups and incumbents trying to develop solid-state batteries, an innovation that holds the promise of dramatically speeding up EV adoption by providing automakers with a safer, cheaper alternative to current lithium-ion batteries.

To become commercially viable, the company needs to deal with three main issues. It must build bigger and multilayered batteries, compared with what it’s testing in a controlled laboratory setting. The current build has only four layers, and the company may need to have as many as a dozen in the commercial version.

It also needs to develop a reliable manufacturing line for certain critical components, such as ceramic separators. Finally, it has to put all those pieces in a factory where it can spread billions of dollars in equipment and machinery costs over large production volumes.