The team at Mercedes-Benz is reporting a breakthrough with the first car powered by a lithium-metal solid-state battery taking to the road.
With range anxiety being at the top of the list for the barriers for EV uptake, Mercedes Benz engineers have worked together to deliver an all-new solid-state battery test program.
The program has developed the Mercedes AMG High Performance Powertrains (HPP), a 100 per cent subsidiary of Mercedes-Benz Group specialising in industry-leading Formula 1 technologies.
The Mercedes-Benz Center of Competence for Battery Systems designed and developed a completely new and innovative battery system.
The testing
After intensive testing on various test benches, the prototype solid-state battery was integrated into an EQS at the end of 2024. The all-electric car from Mercedes-Benz was slightly modified to fit the solid-state battery and was equipped with all accessories to operate it.
The first laboratory vehicle tests were already conducted in Stuttgart at the end of 2024 to prepare for the road tests that started in February 2025.
Member of the Board of Management of Mercedes‑Benz Group AG. Chief Technology Officer, Development and Procurement, Markus Schäfer, highlighted how developing an automotive-scale solid-state battery underlines Mercedes-Benz’s commitment to innovation and sustainability.
“We’re therefore excited to announce that we’ve started road testing with a prototype vehicle equipped with this advanced technology,” Schäfer says.
“We will gain crucial insights into possible series integration of this cutting-edge battery technology.”
The technology
Solid-state batteries are a promising technology in electric mobility. They use a solid electrolyte instead of a liquid one, which enhances cell safety and allows for the use of new anodes like lithium metal, thus significantly outperforming conventional lithium-ion cells.
They also enable next-level energy densities, in combination with a lithium-metal anode. The solid-state technology has the potential to increase the gravimetric energy density for vehicle batteries up to 450 Wh/kg at the cell level and thereby increasing the driving range. Gravimetric energy density refers to the amount of energy stored in a battery cell per unit mass.
This metric is crucial for evaluating the efficiency and performance of battery cells, especially in applications where weight is a critical factor, such as in electric vehicles. Solid-state battery technology reduces the battery weight while improving cell safety.
CEO and Co-Founder of Factorial Energy, Siyu Huang, celebrated being the first to successfully integrate lithium metal solid-state batteries into a production vehicle platform marks a historic achievement in electric mobility.
“This breakthrough demonstrates that solid-state battery technology has moved beyond the laboratory and into real-world application, setting a new benchmark for the entire automotive industry,” Huang says.
“Our collaboration with Mercedes-Benz proves that the future of electric vehicles is not just a vision, but a reality we’re delivering today.”
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 vehicle allows for up to 25 per cent more driving range compared to the same battery weight and size of a corresponding standard EQS battery. Further weight and energy efficiency is achieved through passive battery cooling. The development vehicle is expected to have a range of over 1,000 km (620 miles).