Factorial Energy and SK On signed a memorandum of understanding on July 29, 2026, to study whether Factorial’s FEST® solid-state battery cells — the high-energy-density pack Factorial says is built for longer-range electric vehicles — can be built using SK On’s existing manufacturing network. Factorial filed the notice from Boston. The official release is here, with the same text on Factorial’s site and investor relations.
What the companies agreed to look at
The two will jointly evaluate the technical feasibility and manufacturing questions around FEST®. The idea is to see whether SK On’s lithium-ion plants and know-how can support future solid-state work, rather than assuming a new factory has to come first. The MOU is non-binding except for customary binding provisions. Any real work would need later definitive agreements.
SK On’s footprint, as Factorial printed it
Factorial’s kit describes SK On as a supplier of EV batteries to Hyundai Motor Group, Ford, Volkswagen, and Ferrari. It lists more than 200 GWh of annual production capacity worldwide, including about 100 GWh in the United States, with 22 GWh in Commerce, Georgia, and operations in Tennessee. Those are SK On figures as Factorial printed them. They are not a promise that FEST® cells will fill those lines.
Factorial called the deal a manufacturing-focused partnership with a global battery producer. The official page does not call it the first.
What the two sides said
“A battery breakthrough only matters if it can be manufactured at scale,” said Siyu Huang, CEO of Factorial. “That is what makes this partnership with SK On so significant. Their manufacturing footprint spans some of the world’s most advanced battery facilities, and their expertise will be critical in shaping how solid-state battery technology integrates into global production ecosystems.”
“This collaboration provides an opportunity to evaluate the technical feasibility and manufacturing readiness of solid-state battery technologies, drawing on SK On’s battery technology and manufacturing expertise,” said Ki-soo Park, Head of the Institute of Future Technology at SK On. “SK On will continue to explore collaboration opportunities in next-generation battery technologies.”
The companies said they will look at future solid-state work for mobility and high-performance markets. Factorial’s kit also lists aerospace systems and hyperscale data centers as possible uses for its solid-state platforms.
Mercedes already put Factorial cells on the road
Mercedes-Benz has its own official story on this chemistry. In late August it ran a lightly modified EQS with a lithium-metal solid-state pack from Stuttgart to Malmö — 1,205 km (749 miles) with no charging stop, and 137 km (85 miles) of range left on arrival. The cells came from Factorial and use FEST®. The pack was developed with Mercedes-AMG High Performance Powertrains in Brixworth. Mercedes said usable energy was up 25% versus a standard EQS battery of comparable weight and size. Markus Schäfer, the company’s chief technology officer, said the goal is series production by the end of the decade. Our standalone write-up is here. Official Mercedes: the U.S. release is here, and the earlier road-test kickoff is here. That long-distance run is not part of the SK On memorandum. It is the same Factorial cell technology the two battery companies now want to study on SK On’s lines.
Factorial’s own notice also mentions Stellantis-lab testing of 77 Ah cells and a fully built Dodge Charger Daytona demonstration vehicle. Those lines sit in Factorial’s about text, not in the SK On filing.
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