Mercedes-Benz and Stellantis are investing in Massachusetts-based solid-state battery firm Factorial Energy, becoming the latest in a series of automakers to back development of solid-state batteries.

Multiple solid-state battery firms have cropped up promising improvements in performance over the lithium-ion chemistry used in nearly all current U.S. electric cars. Factorial promises range improvements of up to 50% with its cells.

Solid-state batteries get their name from a solid electrolyte, as opposed to the liquid electrolyte used in lithium-ion cells. Unlike most rivals, Factorial explicit stated in a press release that its battery chemistry is "compatible with conventional lithium-ion battery manufacturing environments.”

Factorial, which also recently netted an investment from Hyundai, is still developing its tech. The company said it reached an important 40-amp-hour benchmark for a solid-state cell that works at room temperature earlier this year, but promising lab results do not automatically translate to a commercially-viable product.

Jeep Wrangler Magneto concept

Jeep Wrangler Magneto concept

Several other automakers are pursuing solid-state cells. Ford and BMW have invested in another solid-state tech company—Solid Power—which earlier this year claimed third-party safety tests showed its battery tech to be safer than current lithium-ion chemistry.

Ford's plans with battery manufacturer SK Innovation are aimed at using about 70% of the equipment from lithium-ion cell production to scale up solid-state cells. Meanwhile BMW has targeted 2025 for a solid-state-powered vehicle prototype.

Volkswagen meanwhile has been investing in QuantumScape, a relationship that goes back to 2012. VW has said it will use solid-state batteries in a limited form by 2025.

Nissan just earlier this week pointed to 2028 as when it expects solid-state batteries to be production-ready—with a pilot plant coming online as soon as fiscal year 2024. Toyota has also indicated that it plans to introduce solid-state batteries later in the decade.