September 8, 2026 - Has ProLogium Finally Cracked Solid-State Cells?

This is the Telemetry Transportation Daily for September 8, 2026, and I'm Sam Abuelsamid, Vice President of Market Research for Telemetry. 

During a recent GreenCars Podcast interview, GM's Vice President of Battery and Sustainability, Kurt Kelty, expressed skepticism about the prospects for solid-state batteries in the next several years. Kelty said, "It's always been that chemistry of the future; it's still that chemistry of the future." If the latest news from Taiwan's ProLogium holds up, that future may be very close.  ProLogium is one of several solid-state battery developers that Mercedes-Benz has invested in, along with Factorial Energy. Last year, Mercedes-Benz tested one of its EQS sedans with a Factorial semi-solid-state battery, and it went 749 miles on a charge. 

Unlike Factorial's current cells that use a non-flammable gel-like electrolyte, ProLogium is using a true solid ceramic electrolyte and separator. This approach has been the goal for many companies, although manufacturing at scale and durability have proven to be challenging. ProLogium launched a manufacturing facility in Taiwan in 2024, and that has capacity for 0.5 GWh of cells, enough for about 6,000 80-kWH packs. The Taiwan plant is set to double capacity by 2030, but ProLogium plans a 44-GWh plant in Dunkirk, France, as well, with initial production in 2028. 

The plant in Taiwan is producing large-format pouch cells from its generation 3.5 design that have a 185.4 amp-hour capacity. These cells have now been independently tested by Tuv in Germany and yielded very promising results with 381 Wh/kg gravimetric energy density and 903 Wh/L volumetric energy density from a nickel-cobalt-manganese cathode chemistry. Current NMC cells typically produce about 260-300 Wh/kg. ProLogium claims these cells will also withstand over 1,000 charge cycles, which would make them suitable for vehicle use. UL also tested the cells to the latest Chinese GB/T standard to validate that they are, in fact, solid-state, achieving a weight loss of less than 0.05% after six hours in a vacuum at 120 °C. 

The manufacturing process for ProLogium cells is in many ways similar to current production cells, so if the materials can truly hold up with scaling volume, this could be one of the first mass-produced solid-state cells, although truly significant volumes probably won't arrive until close to the end of the decade.