SK On enters US ESS market with $1.4 bil. LFP battery deal

SK On's containerized energy storage system is on display at its exhibition booth for the 2025 World Climate Industry Expo at BEXCO in Busan, Aug. 27. Courtesy of SK On

SK On has received its first large-scale order for energy storage systems (ESS) in the United States, signing an agreement estimated at $1.4 billion to supply up to 7.2 gigawatt-hours (GWh) of ESS products equipped with lithium iron phosphate (LFP) batteries.

The Korean battery maker announced Thursday it will provide Flatiron Energy Development with 1 GWh of containerized ESS products equipped with LFP batteries starting next year for the Colorado-headquartered renewable energy firm’s project in Massachusetts. SK On also secured the right of first offer for Flatiron’s plan to additionally install 6.2 GWh of ESS in the U.S. by 2030.

“This deal is meaningful because it expands both our product and business portfolios,” said Choi Dae-jin, head of ESS business at SK On. “We will keep strengthening our presence in the North American ESS market using our advanced technologies and production capabilities.”

Jonathan Poor, chief operating officer and co-founder of Flatiron, said the company anticipates deploying several projects under this partnership over the coming years.

SK On will begin mass production of LFP batteries for ESS by converting part of its electric vehicle battery production lines at SK Battery America, its wholly owned subsidiary in Georgia.

Building on its partnership with Flatiron, the Korean company plans to continue supplying high-quality U.S.-made LFP batteries to support the country’s rapidly growing ESS market.

According to SK On, its ESS will feature a modular design for flexible scalable solutions, along with advanced safety measures including heat propagation prevention and electrochemical impedance spectroscopy-based battery diagnostics for reliable operation.