US solid-state battery developer Factorial Energy has signed a memorandum of understanding with South Korea's SK On to jointly evaluate how Factorial's FEST solid-state cell technology could be manufactured at scale inside SK On's global battery network — a partnership that pairs one of the leading solid-state chemistries with more than 200 GWh of installed lithium-ion capacity.
What the MOU covers
Under the non-binding agreement, the two companies will assess the technical feasibility and manufacturing readiness of Factorial's FEST platform inside SK On's existing production footprint, which spans roughly 200 GWh of annual capacity worldwide — including about 100 GWh in the United States across Georgia and Tennessee. SK On is one of the world's largest EV cell suppliers, serving Hyundai Motor Group, Ford, Volkswagen and Ferrari.
The parties will assess whether SK On's existing lithium-ion infrastructure can be adapted to support future solid-state lines, or whether new equipment classes will be required. Any definitive commercial or capital commitments would follow separate binding agreements.
Why manufacturing scale is the fight
Solid-state cells promise higher energy density, faster charging and better safety than today's liquid-electrolyte lithium-ion, but the industry's central bottleneck has shifted from chemistry to production. "A battery breakthrough only matters if it can be manufactured at scale," Factorial CEO Siyu Huang said in the announcement, framing SK On's footprint as the accelerant.
Where Factorial has been active
Factorial and Stellantis have already begun road-testing FEST cells in a Dodge Charger Daytona this year, and Factorial recently secured its first commercial drone battery order — a signal that its target markets stretch beyond passenger EVs into aerospace and, per the SK On announcement, hyperscale data centers.
Factorial listed on Nasdaq under the ticker FAC earlier this summer via a SPAC deal after its June combination. SK On, meanwhile, is scaling US output via joint ventures with Hyundai — including the recent $5B Bartow, Georgia plant opening — even as its core EV cell business absorbs the industry's demand slowdown.
Timeline caveats
Solid-state battery timelines have slipped repeatedly across the industry, and Factorial's public disclosures continue to point to automotive integration on a multi-year horizon rather than 2026 volume production. The SK On MOU does not shift that timeline directly, but a credible manufacturing partner reduces one of the biggest execution risks facing the company as it heads toward its first commercial contracts.
Reporting based on coverage from Factorial Energy, SK On and Evertiq.