High-Throughput Screening of Solid-State Li-Ion Conductors Using Lattice-Dynamics Descriptors

Area of Science:

• Materials Science
• Solid-State Chemistry
• Computational Materials Science

Background:

• Low lithium-ion migration barriers correlate with low average vibrational frequencies (phonon band centers).
• This correlation serves as a descriptor for superionic conduction, guiding the search for new materials.

Purpose of the Study:

• To computationally screen approximately 14,000 lithium-containing compounds from the Materials Project database.
• To identify novel promising lithium-ion conductors using a descriptor based on lattice dynamics.

Main Methods:

• Optimized an efficient computational approach to calculate the average vibrational frequency (phonon band center) for pre-screened compounds.
• Pre-screening involved assessing structural stability, band gap, and elemental composition.
• Selected compounds based on low computed Li phonon band center, large electrochemical stability window, and structural stability.

Main Results:

• Successfully computed phonon band centers for approximately 1,200 compounds.
• Identified 18 compounds predicted to be promising lithium-ion conductors.
• Synthesized Li3ErCl6, which demonstrated a room-temperature conductivity of 0.05-0.3 mS/cm.

Conclusions:

• The study validates the use of lattice dynamics, specifically phonon band centers, as a descriptor for discovering new lithium-ion conductors.
• The computational screening approach effectively identifies promising candidates for solid-state electrolytes.
• The successful synthesis and characterization of Li3ErCl6 highlight the predictive power of this methodology.