Safer, lighter, more efficient and 25 percent longer range in the first vehicle: the solid-state cell chemistry means higher energy density and weight reduction, with improved driving efficiency and cell safety.
Mercedes-Benz, together with Mercedes AMG High Performance Powertrains (HPP) based in Brixworth, UK, developed and patented a new and innovative solid-state battery pack.
Mercedes-Benz integrated the solid-state battery, with cells from US-based solid-state battery leader Factorial Energy, into a slightly modified EQS.
Road tests with the new solid-state battery in a 1,000km EQS test car started in February 2025.
Mercedes-Benz engineers from the road and racetrack and Factorial cell engineers have worked together on delivering an all-new solid-state battery test programme, which has brought the first car powered by a lithium-metal solid-state battery to the road.
HPP, a 100 percent subsidiary of Mercedes-Benz Group specialising in Formula 1 technologies,
and the Mercedes-Benz Center of Competence for Battery Systems designed and developed a completely new and innovative battery system.
In addition to its prowess on the racetrack, HPP is capable of rapidly transferring F1 technologies and know-how into high-performance automotive projects.
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.
“Developing an automotive-scale solid-state battery underlines our commitment to innovation and sustainability,” said Markus Schäfer, Member of the Board of Management of Mercedes-Benz Group AG. Chief Technology Officer, Development & Procurement.
“We’re therefore excited to announce that we’ve started road testing with a prototype vehicle equipped with this advanced technology.
“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 450Wh/kg at the cell level, 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.
“Being the first to successfully integrate lithium metal solid-state batteries into a production vehicle platform marks a historic achievement in electric mobility,” said Siyu Huang, CEO and Co-Founder of Factorial Energy.
“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.
“Our collaboration with Mercedes-Benz proves that the future of electric vehicles is not just a vision, but a reality we're delivering today.”
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 on-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 vehicle allows for up to 25 percent more driving range compared with the same battery weight and size of a corresponding standard EQS battery.
Further weight and energy efficiency are achieved through passive battery cooling. The development vehicle is expected to have a range of over 1,000km (620 miles).
Over the next few months, Mercedes-Benz will further test the solid-state battery and its overall performance in an electric vehicle with extensive laboratory and road tests.