SK on develops new solid-state electrolyte with enhanced battery performance

Advanced Functional Materials. [Courtesy of SK on]

SK on Co., a pure-play battery maker under South Korea’s SK Group, has successfully developed a new oxide-based solid-state electrolyte with the world’s highest lithium-ion conductivity. This development is expected to significantly enhance the competitiveness of all-solid-state batteries.

SK on announced on Thursday that the company and a research team led by Professor Park Hee-jung of Dankook University’s Department of Materials Science and Engineering jointly developed the new oxide-based solid-state electrolyte and that the research results have been featured in the cover paper of the prestigious academic journal Advanced Functional Materials.

The company has also completed patent applications for the technology both domestically and internationally.

SK on and the research team adjusted the additives of the oxide-based solid-state electrolyte material LLZO (lithium, lanthanum, zirconium, oxygen) to improve lithium-ion conductivity by 70 percent compared to existing levels, achieving the world’s highest conductivity.

Lithium-ion conductivity refers to the speed at which lithium ions move within the electrolyte. A higher speed leads to increased battery output and faster charging capabilities. The technology also ensures uniform control of the microstructure of LLZO, securing atmospheric stability.

Solid electrolytes are usually susceptible to moisture and carbon dioxide, causing a decline in their functionality over prolonged exposure, but this solid-state electrolyte exhibited excellent stability, SK on said.

SK on Co.’s polymer-oxide composite all-solid-state batteries. [Courtesy of SK on]

Oxide-based solid-state electrolytes, despite having lower ionic conductivity compared to sulfide-based electrolytes, have excellent chemical stability. They exhibit reduced reactivity with cathode materials, thus inhibiting issues like lithium dendrite formation that can cause fires. This allows for the replacement of graphite anodes with high-capacity lithium metal anodes.

The capacity of batteries can also be significantly increased using this technology. In particular, the maximum operating voltage of a lithium-ion battery (LiB) using a liquid electrolyte is up to 4.3 volts (V), but with an oxide-based solid-state electrolyte, this increases to up to 5.5 V.

When applied to battery manufacturing, it is theoretically possible to increase battery capacity by up to 25 percent, SK on explained.

The solid-state electrolyte material can be utilized not only for all-solid-state batteries based on NCM (nickel, cobalt, manganese) cathode materials but also for next-generation batteries such as lithium-sulfur batteries and lithium-air batteries, which can be solidified.

It can also be applied to polymer-oxide composite all-solid-state batteries that SK on is developing.

If applied to next-generation batteries, it could satisfy both safety against fires and the potential for long-distance driving.

“This solid-state electrolyte with both ionic conductivity and atmospheric stability is an innovative technology with significant ripple effects for making high-quality all-solid-state batteries,” said Choi Kyung-hwan, head of SK on’s next-generation battery research center. “We will take the lead in seizing growth opportunities in the next-generation battery field based on our future technological competitiveness.”

Currently, SK on is developing two types of all-solid-state batteries: polymer-oxide composites and sulfides. The company aims to produce early-stage prototypes of both types in 2026 and commercialize them in 2028. The company’s next-generation battery pilot plant, currently under construction at its battery research center in Daejeon, South Chungcheong Province, is expected to be completed next year.