Mercedes together with the Mercedes-AMG F1 team tested the solid-state battery developed together with american company Factorial Energy for the first time on a Mercedes EQS.
At the end of 2021, Mercedes signed an agreement with US firm Factorial Energy to develop a new generation of solid-state batteries for use in electric cars. Factorial Energy was the first company in the world to succeed in developing a solid-state technology that has been scaled to 40 Ah, works at room temperature and can adopt the majority of existing cell manufacturing equipment. Solid-state batteries existed before but were small in capacity for use in the electric cars.
After intensive testing on various test benches, the new battery was integrated into a slightly modified Mercedes EQS in late 2024. The first laboratory tests were conducted in Stuttgart at the end of 2024, and on-road testing began in February 2025.
Solid-state batteries use a solid electrolyte instead of a liquid one. Basically, the electrolyte, i.e. the separating layer between the anode and the cathode, is no longer liquid but solid. In solid-state batteries, the anode and cathode may or may not contain lithium, and the electrolyte may also have a different composition. The solid electrolyte must have a highly permeable texture to allow the free flow of electrons when charging and discharging the battery. Because the solid-state electrolyte does not change its state of aggregation with decreasing temperatures, solid-state batteries will provide similar autonomies in winter as in summer.
On the other side, 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 solid-state battery is equipped with pneumatic actuators that interact with the cell volume change during charging and discharging.
Electrolyte solid enhances cell safety and allows for the use of new anodes like lithium metal, thus significantly outperforming conventional lithium-ion cells. The new lithium-metal anode allows for a higher energy density of up to 450 Wh/kg which will give EQS a 25% longer range compared to a standard Li-Ion battery of the same weight and size. This energy density is almost double that of a standard Li-Ion battery.
This means that the EQS 450+, which has a WLTP range of 799 km with the new 118 kWh net capacity battery, will be able to travel over 1000 km with the new solid-state battery.
Mercedes plans to use this kind of battery on high-end models such as the electric G-Class and future Mercedes-AMG electric models. Such a battery option is already planned for the Mercedes G 580 EQ. Mercedes isn’t giving details about the price of such a battery for now but in 2021 it says it wants to offer them at similar prices with Li-Ion batteries.
