Solid-state EV battery that retains 72% capacity in extreme cold set for mass production

A new solid-state battery developed by one of the major Chinese automakers has passed critical performance and safety tests and is now in pilot production mode.

Dongfeng's first solid-state battery generation offers an energy density of 350 Wh/kg, which might sound far from the technology's theoretical peak of 500 Wh/kg, but is apparently stable and cost-effective enough to enter mass production in 2026. Arguably, this matters more for establishing the viability of solid-state batteries for electric vehicle powertrains than chasing top specs with prototypes in the lab.

According to Dongfeng, its first solid-state battery will allow an EV range of 1,000 km while fitting in the footprint of current batteries with liquid electrolyte. That number is most likely calculated on China's CLTC cycle which is about a third less stringent than the EPA estimate, so the equivalent number in the US would be over 400 miles on a charge in real-life scenarios.

Solid-state batteries have many other advantages besides higher energy density, though. They are safer thanks to the lack of volatile liquid electrolyte, can be charged faster, and retain their capacity much better in extreme temperatures. In the case of Dongfeng's solid-state battery that is set for mass production next year, the cold weather test returned 72% capacity retention at -30°C (-22 degrees Fahrenheit). That is 20% higher than regular lithium batteries with liquid electrolytes, making it suitable for electric cars in cold climates.

The new solid-state battery also passed the high temperature, or the so-called hot box test, and was able to safely withstand temperatures of up to 170°C (338 degrees Fahrenheit), much higher than the required 130°C.

Dongfeng says that it is also working on a fast charging version of its solid-state battery that will be able to take advantage of 2 MW chargers, as well as on a solid-state battery that will bring it closer to the theoretical 500 Wh/kg energy density of the sulfide-based technology, though its production is only expected after 2027. That is when other major players, like CATL, Samsung, or Toyota, have vowed to bring vehicles with true solid-state batteries to market, too. 

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