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.
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.
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 % 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).
