Stellantis N.V. and Boston-based Factorial Energy have advanced their joint solid-state battery program with the internal validation of a 77-amp-hour, automotive-sized pouch cell built on Factorial’s FEST (“Factorial Electrolyte System Technology”) platform. The milestone clears an early technical hurdle for the partners as they work toward commercial deployment in future Stellantis electric vehicles.
The newly validated FEST cell carries a rated capacity of 77 Ah. Factorial reports a >600-cycle life to date, with testing “progressing towards automotive qualification,” according to the Stellantis announcement. Fast-charge performance is another headline metric: the cell can move from 15% to 90% state of charge in 18 minutes at room temperature, discharging at rates up to 4C while operating in ambient conditions ranging from –30 °C to 45 °C. Demonstration fleet slated for 2026 Dodge Chargers, according to CarScoops.
A partnership with Factorial key
Factorial Energy developed the electrolyte and manufacturing recipe that underpin the FEST architecture. The company’s technology platforms include both FEST (Factorial Electrolyte System Technology) and Solstice, which use electrolyte innovations that enable safe and reliable cell performance with high-capacity cathode and anode materials.
“Reaching this level of performance reflects the strengths of our collaboration with Factorial… bringing us closer to lighter, more efficient batteries that reduce costs for our customers,” said Ned Curic, Stellantis chief engineering and technology officer.
Stellantis made a $75 million investment in Factorial in 2021 and became a strategic partner in the venture. The automaker joins Mercedes-Benz Group, Hyundai Motor Company and Kia Corporation on Factorial’s partner roster.
The April validation campaign involved a batch of automotive-size pouch cells that underwent testing protocols that Stellantis and Factorial engineers defined. While neither company disclosed exact throughput figures, Curic noted that the collaboration is tracking against Stellantis’s internal timetable for placing FEST cells in a demonstration fleet by 2026 for real-world data logging.
From Stellantis’s vantage point, solid-state batteries offer a trifecta of advantages: higher energy density, faster recharging and improved safety. The 375 Wh/kg energy density demonstrated by these cells represents a significant upgrade compared to current commercial lithium-ion batteries.
“Battery development is about compromise. While optimizing one feature is simple, balancing high energy density, cycle life, fast charging, and safety in an automotive-sized battery with OEM validation is a breakthrough,” said Siyu Huang, CEO of Factorial Energy.
Bottom line
While the validated cells represent significant technical progress, commercializing solid-state batteries at gigawatt-hour scale presents several challenges: Manufacturing processes for new battery materials need optimization for automotive standards. Battery pack designs must be developed to maintain proper conditions across the battery’s lifetime. Finally, supply-chain development for specialized materials will be necessary before reaching commercial volumes.
The 77 Ah FEST pouch cell gives Stellantis a legitimate technical talking point and advances Factorial closer to the front of the solid-state battery development race. Yet the journey from validation cells to mass production remains substantial. For now, Stellantis has a validated cell, a roadmap for demonstration vehicles by 2026, and significant manufacturing development ahead.
