A modified Mercedes EQS drove 1,205 kilometres from Stuttgart to Malmö without charging.
Its lithium-metal solid-state pack carried 25% more usable energy at a comparable size and weight.
The car arrived with 137 kilometres of indicated range remaining.
Mercedes-Benz has completed a long-distance road test of a solid-state battery in a lightly modified EQS. The vehicle travelled 1,205 kilometres from Stuttgart, Germany, to Malmö, Sweden, without recharging and arrived with 137 kilometres of range shown on the dashboard, according to the company.
The route followed the A7 and E20 through Germany and Denmark and crossed to Sweden without using a ferry. It extended the company's previous road-distance record for an electric test car by three kilometres.
Solid-state cells replace the flammable liquid electrolyte used in conventional lithium-ion batteries with a solid material. The test pack used lithium-metal cells supplied by Factorial Energy. Mercedes says it provided about 25% more usable energy than a standard EQS battery while keeping the pack's overall size and weight comparable.
The pack also contains pneumatic actuators that maintain pressure on the cells as their volume changes during charging and discharging. Passive airflow provides cooling, avoiding a large liquid-cooling system. These details matter because a laboratory cell with high energy density does not automatically become a durable vehicle pack; pressure, temperature and expansion must be controlled across thousands of cells and kilometres of vibration.
The journey is a company demonstration rather than an independently certified range test, and Mercedes has not published charging-cycle life, low-temperature performance, manufacturing yield or pack cost. Those measures will decide whether the chemistry can move from a test car into a mass-produced vehicle.
Mercedes expects solid-state technology to enter series production by the end of the decade. The 1,205-kilometre drive shows that a full-size prototype pack can operate on public roads. The next milestone is less dramatic but more consequential: producing the same cells repeatedly, at automotive cost, while retaining capacity over years of daily charging.
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Mercedes-Benz: EQS with solid-state battery completes 1,205-kilometre journey