Pukyong National University

Pukyong National University Research Team Uncovers Mechanism to Enhance Ion Conductivity in Solid Electrolytes

-Research by Prof. Jung Sung-chul’s team published in Journal of Materials Chemistry A, Royal Society of Chemistry (RSC)

-Study proposes strategy using cation substitution for charge control and improved ion conductivity

Pukyong National University (President Bae Sang-hoon) announced on the 13th that a research study by Professor Jung Sung-chul (Department of Physics) and his team on enhancing ion conductivity in solid electrolytes has been published in an international journal of the Royal Society of Chemistry (RSC), UK.

The research team, led by Professor Jung Sung-chul of Pukyong National University and Dr. Jeon Tae-gon, a postdoctoral researcher from the LAMP Project Group, identified the mechanism behind the significant improvement in ionic conductivity of the argyrodite-type solid electrolyte Li6SbS5I for all-solid-state batteries, achieved through cation substitution. This result is considered a meaningful achievement in the growing field of solid electrolytes, which are being actively explored as safer alternatives to liquid electrolytes prone to fire hazards.

Using first-principles calculations, the team discovered that when the cation Sb in the SbS₄ tetrahedron of the Li6SbS5I solid electrolyte is substituted with Si, the Si provides more electrons to the neighboring sulfur anions. These electron-rich sulfur anions then strongly interact with lithium cations passing nearby, drastically lowering the diffusion barrier for lithium ions.

As a result, the ionic conductivity of this solid electrolyte increased significantly―from 4.4 × 10-⁴ mS cm-¹ before substitution to 15.4 mS cm-¹ after substitution. This is one of the highest levels ever reported for solid electrolytes used in all-solid-state batteries and is considered by the research team to be competitive with the ionic conductivity of conventional liquid electrolytes in lithium-ion batteries.

Professor Jung Sung-chul stated, “This study demonstrates that the strategy of charge modulation―adjusting the charge around lithium-ion diffusion paths through aliovalent cation substitution―is highly effective in enhancing the ionic conductivity of argyrodite-type solid electrolytes.”

This research was supported by the Ministry of Education’s LAMP (Leaders in Advanced Materials Platform) program. The findings were published in the prestigious international journal Journal of Materials Chemistry A (Impact Factor: 9.5), issued by the Royal Society of Chemistry, under the title: “Conductivity enhancement of argyrodite Li6SbS5I solid electrolyte via charge modulation around Li diffusion paths through Si substitution.” 〈Pukyong Today〉