Mercedes-Benz claims its EQS prototype fitted with a semi-solid-state battery can surpass 1,000 kilometers of real-world range, an impressive jump from the 627 kilometers achieved by the current EQS 450+. This 25 percent improvement is made possible by Factorial Energy’s FEST cells, which use a quasi-solid electrolyte. The hybrid material blends the stability of solid electrolytes with the performance and manufacturability of liquid ones, enabling the use of lithium-metal anodes known for their higher energy density.

The result? Drivers can expect more time on the road between charges, positioning the EQS at the forefront of long-distance EV travel. As the battery expands and contracts during use, pneumatic actuators support the structure, ensuring efficiency and longevity under pressure. This innovation boosts range and maintains performance consistency over repeated charging cycles.

Solid-state batteries are hailed for their fire-resistant nature thanks to the absence of flammable liquids, and the EQS prototype goes a step further with advanced pressure management to reduce dendrite growth, a key safety concern in lithium-metal designs. By keeping the cells under constant pressure using Mercedes’ patented floating cell carrier, the battery’s durability and safety are enhanced significantly.

On the sustainability front, Mercedes and Factorial Energy aim to eliminate hazardous solvents through a dry coating method in their upcoming all-solid-state “Solstice” cell. This process reduces energy use and cuts out traditional formation stages, streamlining production and lowering the environmental footprint. As a result, Mercedes not only improves performance but also leads a shift toward greener, safer battery manufacturing.

After years of collaboration and the recent delivery of test cells in 2024, Mercedes has begun an intensive testing program to explore real-world integration of the semi-solid-state battery. This development is more than theoretical. Mercedes owns an equity stake in Factorial Energy and has full access to next-generation battery platforms like Solstice, which promises an 80 percent range boost over lithium-ion counterparts.

While other automakers, including Toyota, continue to experiment with solid-state tech, Mercedes appears to be leading the race toward commercialization. By bridging lab innovation with production feasibility, the EQS battery project demonstrates that the future of electric mobility is not only closer than expected, it’s being built now.