SK On offered a solution to the performance degradation problem long cited as a hurdle to commercializing silicon-anode solid-state batteries by developing a new material.
SK On said on the 15th that, together with research teams led by Professors Jeong Yun-seok and Kim Jeong-hun at Yonsei University, it developed a new binder material—an electronically conductive polymer (PPMA)—optimized for silicon anodes. PPMA secures both conductivity and adhesion, making it a material that can improve the structural instability that occurs during repeated charging and discharging in silicon-anode solid-state batteries.
Silicon anodes are drawing attention as a key material for high-energy-density batteries because, theoretically, they have about 10 times the storage capacity of graphite. But the issue of volume changing by more than 300% during charging and discharging has been cited as a barrier to commercialization. When battery expansion and contraction break contact between particles and increase internal resistance, it becomes difficult to fully deliver battery performance, including energy density and capacity as well as lifespan, output, and efficiency.
Solid-state batteries conduct electricity through contact between solid particles. Because it is difficult to restore contact once it is lost, approaches have included increasing the use of binders—adhesive materials—or applying high pressure. However, polyvinylidene fluoride (PVDF), a material widely used as a binder, is highly insulating, creating a limitation in that increasing its use makes it difficult to enhance electrode performance.
SK On and Yonsei University researchers found that the cause of performance degradation in low-pressure environments lies in electron movement within the electrode rather than lithium-ion transport. Accordingly, the newly developed PPMA material is designed to stably form pathways for electrons to move throughout the electrode while strengthening the bonding of silicon particles.
The newly developed binder can also simplify processes and improve production efficiency. Previously, special solvents and high pressure were required, but PPMA enables water-based processing, reducing environmental burdens and manufacturing expense. Pressure was also cut by more than 80%.
The research was published Dec. 5 last year in the international journal Nature Communications. Reviewers noted that the study stably implemented a conductive polymer binder—whose use had been limited in conventional liquid electrolyte-based batteries—in a solid-state battery environment, expanding its applicability.
SK On is pursuing research and development and production preparation in parallel with the goal of commercializing solid-state batteries. SK On has built a solid-state battery pilot plant at its Future Technology Center in Daejeon, with a target for commercialization in 2029.
Park Gi-su, head of SK On's Future Technology Center, said, "Through industry-academia collaboration, we made meaningful progress in next-generation solid-state batteries," and added, "We will continue to work with academia to accelerate innovation in next-generation battery technology."