On September 4, 2025, SK On announced that it has signed a 1 GWh energy storage system (ESS) supply agreement with U.S.-based renewable energy company Flatiron Energy Development. Under the agreement, SK On will provide containerized ESS products equipped with LFP batteries for a project led by Flatiron in Massachusetts, starting in 2026.
Additionally, SK On has obtained the “Right of First Offer” for Flatiron’s upcoming projects in Massachusetts and other U.S. regions, totaling 6.2 GWh in capacity by 2030. Through mutual consultation, SK On is expected to supply up to 7.2 GWh of ESS products over a four-year period beginning in 2026.
To meet growing demand in North America, SK On plans to begin mass production of ESS-dedicated LFP batteries in the second half of 2026. The company will convert part of its electric vehicle battery production lines at its SK Battery Plant in Georgia to focus on ESS-specific products, establishing a agile localized supply chain.
ESS Products – Flexible and Cost-Competitive Batteries
Compared to electric vehicle batteries, ESS products have more flexible size and weight requirements. SK On will leverage cost-competitive and highly stable LFP pouch cells for its ESS solutions.
SK On’s ESS products stand out in the market due to their space-efficient pouch cell design and high-voltage module architecture. While conventional ESS systems often require rack-level design to maintain rated voltage, SK On employs a modular design at a smaller unit than rack-level, enabling flexible capacity configuration and expansion while offering highly customized system solutions.
The company has also significantly enhanced product safety by implementing a “Proximity Module Thermal Runaway Prevention Solution” and a battery diagnostics system based on “Electrochemical Impedance Spectroscopy (EIS).” EIS is a technology that analyzes a battery’s internal resistance and reaction characteristics by sending micro electrical signals to diagnose its condition.
Source: WeChat Official Account——鑫椤锂电
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