Li₂₁Ge₈P₃S₃₄: New Lithium Superionic Conductor with Unprecedented Structural Type.

Area of Science:

• Materials Science
• Solid-State Chemistry
• Electrochemistry

Background:

• Lithium superionic conductors are essential for developing safer and more efficient all-solid-state batteries.
• Current solid electrolytes face challenges in achieving high ionic conductivity and stability.

Purpose of the Study:

• To discover and characterize a novel lithium superionic conductor with potential for all-solid-state batteries.
• To elucidate the crystal structure and ionic transport mechanisms of the new material.

Main Methods:

• Synthesis and characterization of Li21Ge8P3S34.
• Structure determination using three-dimensional electron diffraction (3D ED), powder X-ray diffraction, and neutron diffraction.
• Measurement of ionic conductivity and activation energy.

Main Results:

• Discovery of Li21Ge8P3S34, a new composition and structural type in the Li-Ge-P-S system.
• Achieved high lithium ionic conductivity of ~1.0 mS cm-1 at 303 K with low activation energy (0.20 eV).
• Elucidated a unique crystal structure with alternating GeS4 and PS4 tetrahedral slabs facilitating ion transport.

Conclusions:

• Li21Ge8P3S34 represents a promising new solid electrolyte material.
• Its novel structure offers a new design strategy for advanced solid electrolytes.
• Further optimization could lead to high-performance all-solid-state batteries.