E-car: Mercedes-Benz EQS with solid-state battery achieves 1000 km road range

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Solid-state batteries are considered a bet on the future, but only a few have the necessary resources to use them. Nobody wants to talk about breakthroughs at the moment. Of course, every announcement about a further step makes people sit up and take notice. Mercedes has announced its intention to test a solid-state battery from motorsport in a Mercedes EQS on the road. With the same weight and space requirements, the range in the WLTP is to increase from 800 to 1000 km.

Thanks to rapid prototyping, Mercedes-Benz may be making one of the rare transfers from the racetrack to series production. At least that is what the car manufacturer's plan suggests. It has announced that it will be sending a “vehicle based on the EQS” with a battery derived from the motorsport battery on the road for test drives. It doesn't seem entirely trivial, so it's not a direct takeover.

Potential advantages

The use of battery cell technology shows that Mercedes at least still believes in its potential advantages, despite many other promising developments. The manufacturer writes, “Solid-state batteries are a promising technology in electromobility.” At least on the racetrack, where weight savings count for a lot but cost savings count for little, the development of a proprietary cell line is an advantage. It can store more electricity for the same weight or provide the capacity required for a race distance with less weight. With a larger amount of energy that it can store per unit of mass, it offers a higher gravimetric energy density. Net, i.e., at cell level, it should be able to achieve 450 Wh/kg according to the press release. The gross value varies depending on the size of the battery. If many cells are combined in it, it is slightly more favorable, in small packs a little worse.

The energy density factor could help to increase the range in road cars without the weight disadvantage of all cell types commonly used today. Mercedes-Benz sees greater cell safety as an additional benefit. The possibility of so-called thermal runaway, which currently affects the most powerful lithium batteries with nickel-manganese-cobalt (NMC) cell chemistry, should no longer be an issue with solid-state batteries.

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Festkörperbatterie im Mercedes EQS (7 Bilder)

Not a word about the problem areas

Mercedes' motorsport division, Mercedes-AMG High-Performance Powertrain (“HPP”) sources its batteries from Factorial, a battery developer from the USA. One of Factorial's founders recalls that the manufacturer is “setting a historic milestone, successfully integrating solid-state lithium-metal batteries into a production vehicle platform” and, considering the road testing, already sees its products as a “breakthrough” on the way to large-scale production. As recently as the summer of 2024, his Factorial delivered lithium-metal solid-state battery cells to Mercedes-Benz, which was the first B-sample delivery of lithium-metal solid-state batteries to a global OEM.

Breathing cells

One of the many technical challenges of solid-state cells – is the change in volume during charging and discharging, which is also known from other cell chemistries – Mercedes appears to have already mastered and patented this for road use. The latter refers to the storage of the cells in the battery, which allows them to “breathe” unhindered; Mercedes calls it “floating storage”. In addition, there is demand-regulated gas control with the help of specially developed actuators. Both measures together should help to increase performance and service life. Mercedes-Benz makes no mention of progress in the other problem areas of cost, fast-charging capability and durability.

Mercedes expects its solid-state battery to deliver up to 25 percent more range on the road, with weight and size ratios comparable to the standard battery. With passive battery cooling, the development vehicle should be able to travel over 1000 km on one charge. Mercedes-Benz specifies a range of over 800 km in the WLTP for the standard EQS 450+. Mercedes-Benz integrated the battery prototype into an EQS at the end of 2024 following test bench trials. The body of the BEV was slightly modified for this purpose, and the necessary battery peripherals were also installed. Initial tests on the vehicle began in Stuttgart at the end of 2024. Road tests began in February 2025. Further extensive laboratory and road tests in the EQS are to follow.

(fpi)