Battery company SK On is joining hands with U.S. battery startup Factorial Energy to gauge the feasibility of mass-producing solid-state batteries.

On July 29, local time, multiple foreign media reported that the two companies signed a memorandum of understanding and agreed to review whether Factorial’s solid-state battery cell technology can be applied to SK On’s existing lithium-ion battery production lines for mass production.

The core of the cooperation is to check whether solid-state batteries can be put into an actual mass-production system. The two companies plan to jointly review how much, and in what way, SK On’s battery plants and manufacturing equipment can support Factorial’s solid-state battery technology. The technology covered by the cooperation is Factorial’s FEST solid-state battery technology. It is a next-generation battery for electric vehicles that combines a lithium-metal anode and a solid electrolyte to provide high energy density and safety.

Solid-state batteries are considered a next-generation technology that can increase energy density, extend driving range and boost charging speed compared with existing lithium-ion batteries. But securing a solid electrolyte that is conductive and does not crack easily is not easy, and manufacturing costs are also high. Mass-producing them without defects has been pointed to as an obstacle to commercialization.

Siyu Huang (시유 황), Factorial’s chief executive, said, "A breakthrough in batteries only matters if it can be mass-produced." He added, "SK On’s manufacturing capabilities span some of the most advanced battery facilities in the world, and they will play an important role in designing how solid-state battery technology is integrated into the global production ecosystem."

Factorial is also recently conducting real-vehicle validation of FEST cells in North America. Factorial said last month it began testing FEST solid-state battery cells in North America in cooperation with Stellantis. The cells are installed on Stellantis’ STLA Large platform and are being used to power a Dodge Charger Daytona prototype, as part of an on-road testing program.

Performance figures disclosed by Stellantis last year are also drawing attention. Stellantis said Factorial’s 77Ah FEST cell achieved an energy density of 375Wh/kg over more than 600 charge-discharge cycles. The cell maintained performance in extreme temperatures ranging from minus 30 degrees Celsius to 45 degrees Celsius, reached 90 percent from 15 percent state of charge in 18 minutes, and recorded a maximum 4C discharge rate.

Factorial is working with major automakers such as Mercedes, Hyundai Motor, Kia and Stellantis to pursue commercialization of solid-state EV batteries. Earlier this year, Mercedes said an EQS prototype equipped with Factorial’s semi-solid-state battery drove 749 miles, about 1,205 km, on a single charge and still had about 84 miles, about 135 km, of range remaining on arrival. Markus Schaefer (마르쿠스 셰퍼), Mercedes’ chief technology officer, described the technology as a potential 'game-changer' for electric vehicles.

SK On supplies EV batteries to Hyundai Motor Group, Kia, Ford, Volkswagen and Ferrari. Its global annual production capacity is about 200 gigawatt-hours, of which about 100 GWh is installed in the United States.

But SK On has been scaling back its U.S. business as EV demand weakened after the Trump administration abolished federal EV subsidies last year. SK On also ended its joint venture with Ford and decided to shift its focus to the rapidly growing stationary energy storage system market.

Factorial has already signed similar non-binding agreements with LG Chem, battery materials company Philenergy and POSCO Future M. In December last year, it also announced cooperation with POSCO Future M to develop solid-state battery materials. The MOU with SK On is also not legally binding like the other agreements, meaning both companies can withdraw at any time if the cooperation does not lead to meaningful mass-production results.