While electric vehicles have been a solution to help manufacturers move closer to their carbon-neutral goals, electric vehicle batteries are still insufficient in terms of both driving range and charging time. The next step in the evolution of electric vehicle batteries is the development of solid-state batteries.
In a typical electric vehicle, a lithium-ion battery features a liquid electrolyte or a gel-based electrolyte. Still, solid-state batteries (SSB) utilize a solid electrolyte, which can be made from a variety of materials, including glass and ceramic. Why?
The promise of solid-state batteries is greater energy density, smaller form factors, greater heat resistance, and quicker charging times. They're poised to revolutionize the electric vehicle segment, and nearly every leading automaker that produces electric vehicles has its sights on them.
From The Lab To The Real World
For the longest time, solid-state battery technology has been constrained to isolated and controlled testing in lab conditions. However, on February 24, 2025, Mercedes-Benz announced that it had successfully integrated a lithium-metal solid-state battery into a production vehicle platform, marking the first car powered by a solid-state battery to be on the road. This breakthrough in solid-state battery technology has been achieved through the collaboration of Mercedes-Benz and Factorial Energy, who specialize in solid-state batteries.
At the end of 2024, a lithium-metal solid-state battery was successfully installed in a slightly modified Mercedes-Benz EQS, which began laboratory testing shortly after in preparation for road tests scheduled to start at the beginning of 2025. The results were impressive. Compared to a Mercedes-Benz EQS with the same battery size and capacity, this prototype Mercedes-Benz EQS has a 25% longer driving range, with an estimated total driving range of 620 miles. In contrast, the equivalent production EQS model has a driving range of just under 500 miles.
"Developing an automotive-scale solid-state battery underlines our commitment to innovation and sustainability. 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." – Markus Schäfer, chief technology officer, Development & Procurement.
BMW also trialed solid-state batteries in a BMW i7 test vehicle earlier this year. The German automaker partnered with Solid Power, a company that, like Factorial Energy, specializes in solid-state battery cells. BMW has upped its efforts alongside Solid Power since 2022 through its technology transfer agreement. In the BMW i7 test mule, a sulfide-based solid electrolyte was employed, with which the company hoped to investigate battery cell expansion and temperature control. This comes after the company faced issues with its solid-state battery plans in 2023.
BMW Group
"Our BMW i7 ASSB test vehicle on the road is a perfect example of the BMW Group's technology-open mindset. We are continuously advancing the development of new battery cell technologies and are constantly expanding our know-how with valuable partners such as Solid Power.” – Martin Schuster, BMW Group vice president Battery Cell and Cell Module
These are two of the most notable instances of solid-state batteries entering the road testing phase. Other prolific manufacturers, including Nissan and Toyota, have their sights set on road testing, with both companies previously stating that we can expect to see electric vehicles with solid-state batteries in their vehicles by the latter half of the 2020s. Toyota's due date is set a bit earlier than Nissan's.
Refining The Technology
While solid-state batteries are finally making their way into road-going vehicles, considerable effort is being put into improving this already promising technology. Hyundai was one of the most recent examples of improvements made to SSB technology. The Korean automaker unveiled its breakthrough in solid-state battery cell chemistry, which promises to reduce production costs while making solid-state batteries easier to produce by using simpler metals, specifically copper.
Hyundai's solid-state patent proposes using a copper anode layer coated with a protective material to prevent corrosion, which was previously a hindrance to the use of copper in this manner. The patent envisions a solid-state battery with six layers, namely: a copper anode collector layer, a protective coating layer, an additional anode layer, a solid electrolyte layer, a cathode layer, and finally, a current collector layer. However, it's worth mentioning that Hyundai filing a patent doesn't guarantee that we'll see this technology used in road-going models in the future.
Sources: Mercedes-Benz, Factorial Energy, Solid Power, BMW, Porsche, Toyota, Nissan, Stellantis
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This article originally appeared on CarBuzz and is republished here with permission.
