SK On said on the 16th that it has completed a solid-state battery pilot plant inside the Future Technology Institute in Yuseong-gu, Daejeon. The pilot line will produce prototypes for customers and is a facility to evaluate and verify the products' quality and performance. SK On has been conducting joint research on solid-state batteries since it formed a partnership with Solid Power last year.
The newly completed plant spans about 4,628 m2 (about 1,400 pyeong), and SK On plans to develop sulfide-based solid-state batteries on the new pilot line. Some lines will also develop lithium metal batteries, a type of solid-state battery. A lithium metal battery replaces the graphite anode, a key material in lithium-ion batteries, with lithium metal, reducing the weight and volume of the anode material and improving energy density.
SK On plans to commercialize solid-state batteries by 2029. That is one year earlier than its previous goal of 2030. SK On is first pursuing commercialization of a solid-state battery with an energy density of 800 watt-hours per liter (Wh/L). Over the long term, it aims to reach 1,000 Wh/L.
At the pilot plant, SK On applied, for the first time in Korea, its "warm isostatic press (WIP) pre-technology," developed over many years of research and development. WIP is a next-generation calendering process that applies uniform pressure to the electrode at temperatures higher than room temperature (25–100℃) to increase density and performance. The technology minimizes the battery's heat generation reaction and extends its lifespan, but it requires sealing the battery cell and makes continuous automated processing difficult, lowering productivity.
SK On enhanced productivity by inheriting the advantages of the WIP process while addressing its drawbacks through proprietary cell design methods and use of a conventional press process. To that end, SK On developed mixing and electrode composition conditions for battery materials such as active materials (materials that store and supply energy during charging and discharging, improving energy density, lifespan, and safety) and conductive additives (materials that facilitate the flow of electricity and electrons in a battery to stabilize charging speed and lifespan), reducing internal electrode resistance. When internal electrode resistance decreases, the battery's heat generation reaction is minimized.
It also improved the bonding between the electrode and the solid electrolyte and optimized the conditions of the conventional press process to reduce interfacial resistance. When interfacial resistance is low, electricity flows smoothly and the battery charges and discharges stably, extending its lifespan.
Lee Seok-hee, president of SK On, said, "The completion of this solid-state battery pilot plant will serve as the foundation for SK On to leap forward as a robust corporations that does not easily waver in any environmental changes," adding, "We will commercialize solid-state batteries ahead of anyone else and accelerate the electrification era."