US battery developer Factorial and South Korean cell manufacturer SK On have signed a non-binding memorandum of understanding to investigate manufacturing Factorial’s solid-state FEST battery technology using existing lithium-ion production infrastructure.
The companies will jointly assess the technical feasibility and manufacturing requirements of Factorial’s FEST battery platform. No production site, capacity, investment or timetable has been disclosed, and the terms of any commercial collaboration would have to be established through definitive agreements.
Factorial describes FEST as a quasi-solid-state battery technology combining an ultrathin lithium-metal anode, a quasi-solid polymer electrolyte and a high-capacity cathode. The cathode chemistry has not been disclosed.
The company says the platform has a high degree of compatibility with conventional lithium-ion manufacturing equipment. The proposed work with SK On forms part of Factorial’s capital-light industrialisation strategy, under which it aims to use established battery factories instead of constructing entirely new production capacity.
SK On has more than 200 GWh of annual cell production capacity worldwide, around 100 GWh of which is in the US. Its American manufacturing footprint includes 22 GWh of capacity in Commerce, Georgia, and operations in Tennessee.
“A battery breakthrough only matters if it can be manufactured at scale,” said Factorial CEO Siyu Huang. “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.”
FEST agreement is Factorial’s first with a global battery producer
Factorial said this was its first manufacturing-focused agreement with a global battery producer. The companies will also consider potential applications for the technology in mobility and other high-performance markets.
“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.”
Factorial has separately developed Solstice, a sulfide-based all-solid-state battery platform using a dry cathode process. The SK On MoU, however, specifically identifies the quasi-solid-state FEST platform.
FEST cells validated with Stellantis in 2025 had a capacity of 77 Ah and a reported gravimetric energy density of 375 Wh/kg. The companies said the cells completed more than 600 cycles and could charge from 15% to 90% in 18 minutes at room temperature.
The latest MoU does not commit SK On to commercial manufacture. Factorial said it was non-binding apart from customary provisions and that detailed terms would be set out in any subsequent binding agreements.
Photo: a Factorial cell being held in a laboratory setting. NB this is a Solstice all-solid-state cell and not a FEST quasi-solid-state cell.
Credit: Factorial
