Stellantis and US battery developer Factorial Energy have successfully tested solid-state battery cells in an automotive format. The cells are based on Factorialʼs proprietary FEST technology, which is designed for fast charging and high energy density. Stellantis and Factorial have been working together since 2021, when the automaker invested around 75 million US dollars in the battery start-up company.
New electrolyte formulation
According to the group, the cells achieve an energy density of 375 watt-hours per kilogram. Charging from 15 to 90 percent takes 18 minutes at room temperature. The cells with a capacity of 77 ampere-hours have undergone more than 600 charging cycles during validation, which the companies claim represents progress towards automotive suitability. In addition to the energy density, Factorial emphasizes the cellsʼ high performance with discharge rates of up to 4C, as well as their temperature tolerance between -30°C and 45°C. These specifications are achieved by a newly developed electrolyte formulation.
Integration into demonstration fleet
Stellantis plans to integrate the battery cells into a demonstration fleet, starting in 2026, to gain insights into the practical suitability under real-life conditions. In addition to cell development, the partners are also focusing on optimizing the battery pack architecture to reduce overall weight and facilitate integration into existing vehicle platforms.
