Mercedes-Benz and Factorial Achieve Breakthrough in Solid-State Battery Technology

Mercedes-Benz has begun road testing its first electric vehicle (EV) equipped with a lithium-metal solid-state battery, confirming that a 1,000km (620-mile) range is achievable—a major step forward in electric mobility. The prototype vehicle, based on the EQS model, integrates cutting-edge battery technology co-developed with Factorial Energy, marking a significant milestone in battery efficiency, energy density, and safety.

A Leap in Battery Technology

Developed by Mercedes AMG High Performance Powertrains (HPP) and the Mercedes-Benz Center of Competence for Battery Systems, the solid-state battery replaces liquid electrolytes with a solid one, improving energy density and safety. The new battery system offers 25% more range than a comparable EQS battery of the same weight and size, reaching a projected driving range of over 1,000km.

According to Mercedes-Benz, “Safer, lighter, more efficient and 25% longer range in the first vehicle: the solid-state cell chemistry means higher energy density and weight reduction, with improved driving efficiency and cell safety.”

The EV requires no active battery cooling, further optimizing weight and energy efficiency. Gravimetric energy density at the cell level could reach up to 450 Wh/kg, making it a game-changing advancement in electric mobility.

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From Lab to Road: Testing and Development

Mercedes-Benz and Factorial began collaborating in 2021 to develop next-generation battery technology. In 2024, Factorial delivered its first lithium-metal solid-state battery cells for testing under Mercedes-Benz’s proprietary FEST® (Factorial Electrolyte System Technology) platform.

After extensive testing in laboratories and on test benches, Mercedes-Benz integrated the battery into an EQS prototype by the end of 2024. Following successful laboratory trials in Stuttgart, the company launched real-world road tests in February 2025 to evaluate the battery’s long-term performance and potential for series integration.

“Developing an automotive-scale solid-state battery underlines our commitment to innovation and sustainability,” said Markus Schäfer, Chief Technology Officer of Mercedes-Benz Group AG. “We’re therefore excited to announce that we’ve started road testing with a prototype vehicle equipped with this advanced technology. We will gain crucial insights into possible series integration of this cutting-edge battery technology.”

A Milestone for the EV Industry

Factorial Energy CEO Siyu Huang emphasized the breakthrough, stating: “Being the first to successfully integrate lithium metal solid-state batteries into a production vehicle platform marks a historic achievement in electric mobility. This breakthrough demonstrates that solid-state battery technology has moved beyond the laboratory and into real-world application, setting a new benchmark for the entire automotive industry. Our collaboration with Mercedes-Benz proves that the future of electric vehicles is not just a vision, but a reality we’re delivering today.”

The solid-state battery in the EQS prototype is expected to achieve a range of over 1,000km, compared to the 800km (497 miles) range of the current EQS 450+, which has a 118 kWh battery.

Over the next few months, Mercedes-Benz will continue extensive testing on the solid-state battery and its performance in real-world driving conditions, potentially setting a new standard for electric vehicles.

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