Researchers at the Korea Advanced Institute of Science and Technology (KAIST) have significantly enhanced the performance of all-solid-state batteries solely through structural design – and without the costly metals.
(Bottom, from left) Professor Dong-Hwa Seo, Researcher Jae-Seung Kim, (Top, from left) Professor Kyung-Wan Nam, Professor Sung-Kyun Jung, Professor Youn-Seok Jung. Image Credit: The Korea Advanced Institute of Science and Technology (KAIST).
Batteries play a crucial role in contemporary society, powering devices such as smartphones and electric vehicles; however, they are hindered by issues like the risk of fire explosions and high expenses. Although all-solid-state batteries have emerged as a promising alternative, achieving a balance between safety, performance, and cost has proven challenging.
KAIST announced that a research team led by Professor Dong-Hwa Seo from the Department of Materials Science and Engineering, in partnership with teams at Seoul National University, Yonsei University, and Dongguk University, has created a design for core materials in all-solid-state batteries that uses inexpensive raw materials while maintaining high performance and minimizing the risk of fire or explosion. The study was published in the journal Nature Communications.
Traditional batteries depend on the movement of lithium ions through a liquid electrolyte. All-solid-state batteries, on the other hand, use a solid electrolyte. Although this enhances safety, enabling rapid lithium-ion movement within a solid typically requires the costly metals or intricate manufacturing techniques.
The KAIST team concentrated on "divalent anions" such as oxygen and sulfur to establish effective pathways for lithium-ion transport within the solid electrolyte. Divalent anions play a crucial role in modifying the crystal structure by integrating into the fundamental framework of the electrolyte.
The team devised a technology that allows for precise control over the internal structure of economical zirconium (Zr)-based halide solid electrolytes by incorporating these divalent anions.
This design principle, referred to as the "Framework Regulation Mechanism," expands the pathways available for lithium ions and reduces the energy barriers they face during transport. By modifying the bonding environment and crystal structure surrounding the lithium ions, the team facilitated quicker and more efficient movement.
The researchers employed a range of high-precision analytical methods, which included: High-energy Synchrotron X-ray diffraction (Synchrotron XRD), Pair Distribution Function (PDF) analysis, X-ray Absorption Spectroscopy (XAS), and Density Functional Theory (DFT) modeling for electronic structure and diffusion.
The study indicates that electrolytes containing oxygen or sulfur enhanced lithium-ion mobility by a factor of two to four when compared to traditional zirconium-based electrolytes. This suggests that performance levels adequate for real-world all-solid-state battery applications can be realized using cost-effective materials.
In particular, the ionic conductivity at ambient temperature was recorded at roughly 1.78 mS/cm for the oxygen-doped electrolyte and 1.01 mS/cm for the sulfur-doped electrolyte. Ionic conductivity reflects the speed and efficiency of lithium ion movement; a measurement exceeding 1 mS/cm is typically regarded as adequate for practical battery applications at room temperature.
Through this research, we have presented a design principle that can simultaneously improve the cost and performance of all-solid-state batteries using cheap raw materials. Its potential for industrial application is very high.
Dong-Hwa Seo, Study Lead and Professor, Department of Materials Science and Engineering, The Korea Advanced Institute of Science and Technology (KAIST)
“The study shifts the focus from ‘what materials to use’ to ‘how to design them’ in the development of battery materials,” added Jae-Seung Kim, Lead Author, KAIST.
Journal Reference:
Kim, J., et al. (2025) Divalent anion-driven framework regulation in Zr-based halide solid electrolytes for all-solid-state batteries. Nature Communications. DOI: 10.1038/s41467-025-65702-2.