Mercedes-Benz has initiated testing of a solid-state battery from partner Factorial Energy in a modified EQS, aiming to evaluate its efficiency, durability, and performance in the coming weeks. The Stuttgart-based automaker is positioning the technology as a potential breakthrough in electric vehicle range and energy density, with market readiness expected before the end of the decade.
According to a report by Autocar, the solid-state battery is projected to deliver a range exceeding 620 miles (approximately 1,000 kilometers). Mercedes-Benz anticipates that the technology will offer 25% greater range than a lithium-ion battery of the same size and weight. To accommodate the new battery, modifications were made to the EQS, particularly in the battery installation space and housing.
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Factorial Energy, the U.S.-based battery specialist backed by Mercedes-Benz, Stellantis, and Hyundai-Kia, is supplying the test cells. The company has been working on multiple solid-state battery designs, including its Solstice-branded cells, which are still in early development. In June 2024, Factorial provided Mercedes-Benz with B samples of its solid-state cells, featuring a charging capacity of over 106 Ah and an energy density of 391 Wh/kg. The company has also announced plans for an advanced version with an energy density of up to 450 Wh/kg, potentially increasing the driving range of electric vehicles by up to 80%.
The technology being tested in the EQS represents an early phase of Mercedes-Benz’s solid-state battery development. “This is an initial step towards a more advanced solid-state battery, internally codenamed Solstice,” Autocar reported. It remains unclear whether the test battery corresponds to the 391 Wh/kg B samples delivered last year or a different iteration. Factorial has also disclosed plans to scale up its Solstice cells to a 40 Ah capacity in future iterations.
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Mercedes-Benz’s latest testing initiative underscores the automotive industry’s race to bring solid-state batteries to commercial viability, promising significant improvements in energy density and range compared to conventional lithium-ion technology.
