Solid-state battery firm Factorial Energy is nearly ready to provide test cells to automakers, the company said last week in a press release announcing completion of its Series D funding round.

Factorial said it raised $200 million in the round, which was led by Mercedes-Benz and Stellantis. Both automakers announced plans to invest in Factorial last year. Hyundai has been a big investor as well.

Massachusetts-based Factorial said it delivered its first 40-amp-hour solid-state battery in 2021. The company is now building a pilot production facility to scale up production of test cells for customers. The facility will be located in New England and will start construction in early 2022, Factorial said.

STLA Large platform for 8 EVs by 2026  -  2021 Stellantis EV Day

STLA Large platform for 8 EVs by 2026 - 2021 Stellantis EV Day

Factorial claims it will achieve a 50% range improvement with its battery tech, but manufacturing test cells is only one step on the path to full-scale commercialization. Stellantis hopes to use some solid-state cells starting around 2026 that can use some of the same "industrial assets" as current lithium-ion chemistry.

Several other automakers are pursuing solid-state batteries. In November 2021, Nissan said it is targeting use of technology by 2028, as part of a larger plan to ramp up EV production. Toyota began discussing solid-state batteries earlier, but more recently indicated it will debut solid-state tech not in a battery electric model but in a hybrid.

Ford and BMW are among the companies backing Colorado-based Solid Power. That company is also aiming for a form factor that can be used in facilities alongside or replacing lithium-ion cells, and it demonstrated the safety of its cells late last year.