Mercedes-Benz engineers worked in collaboration with Factorial cell engineers to deliver an all-new solid-state battery test program, resulting in the first car powered by a lithium-metal solid-state battery on the road.
Mercedes AMG High Performance Powertrains (HPP), a wholly owned subsidiary of Mercedes-Benz Group specializing in Formula 1 technologies, and the Mercedes-Benz Center of Competence for Battery Systems designed and developed a completely new battery system.
After testing, the prototype solid-state battery was integrated into a Mercedes-Benz EQS Sedan at the end of 2024. The vehicle was slightly modified to fit the solid-state battery and equipped with all accessories to operate it. The first laboratory vehicle tests were conducted in Stuttgart at the end of 2024 to prepare for the road tests that started in February 2025.
Solid-state batteries are a promising technology in electric mobility. The use of a solid electrolyte instead of liquid enhances cell safety and allows for the use of new anodes like lithium-metal. The solid-state technology reduces battery weight and has the potential to increase the gravimetric energy density for vehicle batteries up to 450 Wh/kg at the cell level, thereby increasing electric range. Gravimetric energy density refers to the amount of energy stored in a battery cell per unit mass and is crucial for evaluating the efficiency and performance of battery cells, especially in applications like electric vehicles where weight is a critical factor.
Together with the motorsport experts from HPP, the Mercedes-Benz Center of Competence for Battery Systems developed a prototype solid-state battery with cells from Factorial that can be integrated into a car for road testing. The solid-state battery from Mercedes-Benz features an innovative floating cell carrier, for which a patent has already been granted. When the battery charges, the materials expand, and when it discharges, it contracts. The volume change in solid-state cells refers to the expansion and contraction of the materials inside the battery during charging and discharging. To support the cells during these volume changes, the Mercedes-Benz solid-state battery is equipped with pneumatic actuators that interact with the cell volume change during charging and discharging, which affects the battery’s performance and lifespan.
The solid-state battery in the EQS-based test vehicle allows for up to 25 percent more electric range compared to the same battery weight and size of a corresponding standard EQS battery. Additional weight and energy efficiency is achieved through passive battery cooling. The development vehicle is expected to have a range of over 621 miles.
Over the next few months, Mercedes-Benz will continue its evaluation of the solid-state battery with extensive laboratory and road tests, noting its overall performance in an electric vehicle.