SK On (Seoul, South Korea) announced the completion of its pilot plant for all-solid-state batteries (ASSBs) in South Korea, marking a key step in its push to commercialize next-generation batteries by 2029.
SK On, part of South Korea’s second largest conglomerate SK Group, held the completion ceremony of its ASSB pilot plant at the SK On Institute of Future Technology in Daejeon, about 150 kilometers south of Seoul, on Sept. 15. SK On CEO & President Seok-hee Lee and Head of the Institute of Future Technology Ki-soo Park were among the attendees, along with Andrea Maier, head of Solid Power Korea. SK On and Solid Power have been collaborating on ASSB researches since last year.
“This pilot plant will serve as a cornerstone for SK to leap forward as a strong and resilient company in addressing any changes in business environment,” Lee said. “We aim to remain at the forefront of commercializing all-solid-state batteries to accelerate electrification.”
A pilot plant refers to a facility that produces prototypes and assesses and validates their quality and performance before full-scale production. SK On said its pilot plant will be primarily used to develop sulfide-based ASSBs, with some lines will be dedicated to lithium-metal batteries.
SK On plans to commercialize its ASSBs by 2029, one year ahead of its original target. The company initially aims to commercialize ASSBs with an energy density of 800Wh/L, with a long-term goal of reaching 1,000Wh/L.
SK On said its 4,600-square-meter (50,000 sq. ft.) pilot plant uses its own “Warm Isostatic Press (WIP)-free” technology for ASSB development, making it the first in South Korea to apply such solutions.
A WIP technology is a next-generation pressing process that applies uniform pressure to electrodes at elevated temperatures (25–100 °C) to improve density and performance. Though this solution minimizes battery heat generation and extends lifespan, it requires a cell-sealing process and is difficult to implement in a continuous automated production line, which results in lower productivity.
To retain the advantages of the WIP process while addressing its shortcomings for better productivity, SK On leveraged its unique cell design and normal pressing methods. Specifically, the company optimized the mixing of battery materials, such as active materials and conductive additives, as well as the electrode composition, reducing internal resistance within the electrodes. Reduced resistance helps minimizes heat generation.
Furthermore, SK On improved the bonding between electrodes and solid electrolytes, and optimized pressing conditions to reduce interfacial resistance. Lower interfacial resistance enables smoother ion transport, more stable charging and discharging, and longer cycle life.
In addition to its own research and development, SK On has been is also advancing next-generation battery technologies through partnerships. In May 2025, SK On and South Korea’s Hanyang University reported a threefold increase in cycle life for sulfide-based ASSBs by applying a protective-film technology to lithium-metal anodes. Patent applications for the underlying technologies have been filed both domestically and internationally.