SK On, Success in Developing New Solid Electrolyte... Green Light for Leading High-Quality All-Solid-State Batteries

Joint Development with Dankook University
Expectations for Improved Battery Output and Charging Speed
Published as Cover Paper in a Prestigious International Journal

Polymer composite all-solid-state battery prototype developed by SK On, unveiled at the InterBattery exhibition last March. Photo by SK On

SK On has succeeded in jointly developing a new oxide-based solid electrolyte with world-class lithium-ion conductivity. Lithium-ion conductivity refers to the speed at which lithium ions move within the electrolyte. The faster the speed, the greater the battery output and the faster the charging. This development is expected to further enhance the competitiveness of all-solid-state batteries.

On the 31st, SK On announced that the research results on oxide-based solid electrolytes jointly developed with Professor Hee-Jung Park's research team from the Department of Materials Science and Engineering at Dankook University were published as a cover paper in the globally renowned journal 'Advanced Functional Materials.' The joint research team of SK On and Dankook University has also completed domestic and international patent applications for this technology.

This solid electrolyte significantly increases lithium-ion conductivity while securing atmospheric stability. The SK On-Dankook University research team improved lithium-ion conductivity by 70% compared to existing levels by adjusting the additives of the oxide-based solid electrolyte material 'Li-La-Zr-O (Lithium-Lanthanum-Zirconium-Oxygen, LLZO),' raising it to a world-class level.

Additionally, while higher lithium-ion conductivity typically reduces stability, the SK On-Dankook University team overcame this by uniformly controlling the microstructure of LLZO. Solid electrolytes are generally vulnerable to moisture (H2O) and carbon dioxide (CO2), and their function as electrolytes deteriorates when exposed to the atmosphere for extended periods. However, this solid electrolyte demonstrated excellent stability.

Compared to sulfide-based solid electrolytes, oxide-based solid electrolytes have lower ionic conductivity but superior chemical stability, resulting in less reactivity with cathode materials and the ability to suppress lithium dendrite formation. This allows the graphite anode to be replaced with high-capacity lithium metal. Dendrites are branch-like crystals that accumulate on the anode surface when lithium ions shuttle between the cathode and anode during battery charging and discharging. If these crystals penetrate the separator and reach the cathode, internal short circuits can occur, potentially leading to fires.

Cover of the world-renowned academic journal Advanced Functional Materials (AFM) featuring research results on oxide-based new solid electrolytes jointly developed by SK On and Dankook University. Photo by SK On

Battery capacity can also be significantly increased. In particular, the maximum operating voltage of lithium-ion batteries (LiB) using liquid electrolytes is up to 4.3V, but when using oxide-based solid electrolytes, it can increase up to 5.5V. Applying this to battery manufacturing theoretically allows battery capacity to increase by up to 25%.

This solid electrolyte can be used not only for all-solid-state batteries based on NCM cathode materials but also as a material to solidify next-generation batteries such as lithium-sulfur batteries and lithium-air batteries. Currently, lithium-sulfur and lithium-air batteries under development use liquid electrolytes like lithium-ion batteries, but it is expected that applying this solid electrolyte will enable their conversion into all-solid-state batteries.

It is also applicable to polymer-oxide composite all-solid-state batteries being developed by SK On. Oxide-based solid electrolytes have superior mechanical properties compared to polymer-based ones, which can overcome the limitations of existing polymer all-solid-state batteries by suppressing dendrite formation.

Applying this to next-generation batteries will satisfy both fire safety and long-distance driving capabilities. Choi Kyung-hwan, head of SK On's Next-Generation Battery Research Center, stated, "This solid electrolyte, which possesses both ionic conductivity and atmospheric stability, is an innovative technology for producing high-quality all-solid-state batteries and will have a significant ripple effect. SK On will leverage its overwhelming future technology competitiveness to secure growth opportunities in the next-generation battery field."

Meanwhile, SK On is developing two types of all-solid-state batteries: polymer-oxide composites and sulfide-based. Both types aim to produce early-stage prototypes by 2026 and commercialize them by 2028. The next-generation battery pilot plant currently under construction at the Daejeon Battery Research Institute is scheduled for completion next year.

This content was produced with the assistance of AI translation services.