Road testing started this month on a Mercedes “621 mile” solid-state lithium-metal battery. Jointly developed by engineers from Mercedes AMG performance passenger cars and F1 groups and battery cell engineers from Factorial Energy Inc., the new batteries increase the available power for EVs while reducing battery weight.
Why build a solid-state EV battery
EV batteries with solid-state cells have multiple advantages in addition to range and weight. Solid-state batteries also improve driving efficiency and cell safety.
Engineers from the Mercedes AMG High Performance Powertrains (HPP) and the Mercedez-Benz Center of Competence for Battery Systems groups developed and patented the new technology. HPP specializes in F1 race car technologies, including systems deployed in road cars.
Following lab and bench testing, engineers modified and equipped a Mercedes-Benz EQS Sedan with a solid-state battery. The vehicle was lab-tested in late 2024, and road tests started in February 2025.
Working with Factory solid-state calls, the Mercedes engineers developed a floating cell carrier that allows room for expansion as the cells charge and contractions in discharging. The volume change affects both battery performance and lifespan. The Mercedes battery has pneumatic actuators that interact with cell volume.
The payoff of solid-state batteries
According to Mercedes, lab testing of the EQS test vehicle shows that the solid-state battery provides up to 25% additional electric range compared to a standard battery of the same weight and size. The new Mercedes battery also weighs less and benefits from passive cooling.
The 2025 Mercedes EQS Sedan has a maximum range of 345 miles. Due to the solid-state battery’s multiple advantages, Mercedes expects the EQS with the solid-state battery to have a range of over 621 miles in testing. It will be interesting to learn about the road testing results.
