(197u) First-Principles Study on the Enhancement of Li-Ion Diffusion By Tunning the Anion Rotation in Various Solid-State Electrolyte

Solid-state electrolytes (SSE) are promising materials for use in lithium-ion batteries (LIB) due to their high energy density, wide temperature range, and reduced risk of leakage or explosion. Although high ionic conductivity is one of the most significant factors for electrolytes, it is still remaining a challenge for SSE. Intuitively, cation and anion doping are regarded as the most efficient way to boost Li-ion diffusion. Another way is to analyze the dynamics of cations and anions through the properties of the structure itself, such as anion rotation in plastic crystals. Here, we explore the mechanism of the anion rotation-assisted Li ion diffusion in various anion frameworks in solid-state electrolytes. The Sulfide framework shows the dynamic motion than the halide one, thereby incrementing the Li-ion diffusion. Also, polyanion frameworks such as [PS₄]^3-, play a key role in Li-ion mobility. We also investigate the collective motion between the anion and the Li-ion and construct a way to maintain its motion even at room temperature. This work suggests that the anion rotation may be a critical factor for enhancing ionic mobility and can be used as a useful guideline for designing a next-generation solid-state electrolyte.