- Mercedes-Benz is testing an EQS prototype fitted with a solid-state battery
- The battery is expected to deliver 25% more range than a conventional liquid-type battery
- More advanced solid-state designs could deliver almost double the range of conventional batteries
Mercedes-Benz has begun road tests of its first prototype equipped with a lithium-metal solid-state battery, developed in collaboration with U.S. company Factorial.
The prototype is based on the current EQS electric full-size liftback, with Mercedes targeting a range of at least 621 miles on a single charge, according to the WLTP test cycle used overseas. This represents an approximately 25% increase over the production EQS, which has a maximum WLTP range of 488 miles.
For the EQS prototype, Factorial supplied the battery cells, which were integrated into a battery pack by Mercedes and its U.K.-based Mercedes-AMG High Performance Powertrains division—the same team responsible for the company’s Formula 1 power units. The pack features a patented floating cell carrier with pneumatic actuators that compensate for the expansion and contraction of the cells as they charge and discharge.
Solid-state batteries are a promising advancement in electric mobility. By using a solid electrolyte instead of a liquid, they enhance safety and enable the use of new anode materials, such as lithium-metal, which significantly outperforms conventional lithium-ion cells and allows for higher energy densities.
Mercedes-Benz EQS solid-state battery prototype
In the EQS prototype, the battery is approximately 25% more energy-dense than a conventional liquid-based lithium-ion battery. However, last year, Mercedes and Factorial demonstrated a battery with nearly double the energy density of current lithium-ion cells—around 0.45 kwh per kilogram (approximately 2.2 pounds).
Mercedes first announced its partnership with Factorial on solid-state battery technology in 2021. In 2024, the companies jointly stated that they expect the technology to be commercially viable by the end of the decade. If solid-state technology reaches commercialization, Mercedes’ development of a new micro-converter, combined with innovations in cooling systems, may allow solid-state cells to be integrated alongside other cell types within the same battery pack.
Although solid-state batteries are not a new concept, scaling up production has proven more challenging than anticipated for both automakers and battery manufacturers.
