SK On has successfully co-developed an oxide-based new 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 quicker it recharges. This development is expected to significantly enhance the competitiveness of solid-state batteries.
On the 31st, SK On announced that the research results related to the oxide-based solid electrolyte co-developed with Professor Park Hee-jung’s research team from Dankook University’s Department of Materials Science and Engineering were published as a cover paper in the globally renowned journal, ‘Advanced Functional Materials (IF 19.9)’. The joint research team has also filed domestic and international patents for the technology.
This solid electrolyte drastically elevates lithium-ion conductivity while ensuring atmospheric stability. By adjusting the additives of the oxide-based solid electrolyte material Li-La-Zr-O (Lithium-Lanthanum-Zirconium-Oxygen; LLZO), the SK On-Dankook University research team improved the lithium-ion conductivity by 70% over previous standards (1.7 mS/cm), achieving a world-class level.
Moreover, increasing lithium-ion conductivity typically reduces stability; however, the SK On-Dankook University team overcame this challenge using a technique to uniformly control the microstructure of LLZO. This solid electrolyte, generally vulnerable to moisture (H2O) and carbon dioxide (CO2), displayed remarkable stability over prolonged exposure to the atmosphere.
While oxide-based solid electrolytes have lower ionic conductivity compared to sulfide-based ones, they offer better chemical stability, less reactivity with cathode materials, and can suppress lithium dendrite formation, allowing for the potential replacement of graphite anodes with high-capacity lithium metal ones.
Battery capacity can also be significantly increased. Notably, the maximum operating voltage for liquid electrolyte-based lithium-ion batteries is up to 4.3V; however, utilizing oxide-based solid electrolytes can extend this to as high as 5.5V. If applied in battery manufacturing, it could theoretically boost battery capacity by up to 25%.
This solid electrolyte can also be utilized in next-generation batteries such as lithium-sulfur and lithium-air batteries, which are considered promising. Currently in development, lithium-sulfur and lithium-air batteries use liquid electrolytes like LiB, but it is anticipated that they can be transformed into solid-state batteries using this solid electrolyte.
It can potentially be applied to the polymer-oxide composite solid-state batteries that SK On is developing. This is because oxide-based solid electrolytes have superior mechanical properties compared to polymer ones, helping to suppress dendrite formation and overcome the limitations of existing polymer solid-state batteries.
Applying this in next-generation batteries could meet both fire safety and long-range driving possibilities.
Choi Kyung-hwan, head of SK On’s Next-Generation Battery Research Center, stated, “This solid electrolyte, which combines ionic conductivity and atmospheric stability, is an innovative technology for creating high-quality solid-state batteries and will have significant ripple effects.” He further emphasized, “SK On will seize growth opportunities in the next-generation battery sector based on overwhelming future technological competitiveness.”
SK On is developing two types of solid-state batteries: polymer-oxide composite and sulfide-based. The aim is 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.
Lee Sang-jin daedusj@autodiary.kr