Sn-Substituted Argyrodite Li₆PS₅Cl Solid Electrolyte for Improving Interfacial and Atmospheric Stability

Area of Science:

• Materials Science
• Electrochemistry
• Solid-state Chemistry

Background:

• Sulfide solid electrolytes offer excellent ionic conductivity and formability.
• A key challenge is their reactivity with moisture, producing toxic H2S gas and degrading performance.

Purpose of the Study:

• To enhance the stability of argyrodite Li6PS5Cl solid electrolytes against atmospheric moisture.
• To improve the interface between Li metal and the solid electrolyte by incorporating tin (Sn).

Main Methods:

• Synthesized Sn-substituted argyrodite solid electrolytes using liquid-phase synthesis.
• Characterized structural and compositional properties using X-ray diffraction (XRD) and energy-dispersive X-ray spectroscopy (EDS).
• Evaluated electrochemical performance via electrochemical impedance spectroscopy (EIS) and DC cycling, and moisture stability using a gas sensor.

Main Results:

• XRD confirmed the argyrodite structure with peak shifts indicating successful Sn substitution.
• SEM and EDS showed increased particle size and uniform component distribution.
• Sn substitution (X=0.05) slightly reduced ionic conductivity but provided stable cycling for ~500 hours.
• Gas sensor measurements confirmed improved stability against H2S generation upon moisture exposure.

Conclusions:

• Liquid-phase synthesis is suitable for large-scale production of argyrodite Li6PS5Cl solid electrolytes.
• Partial Sn substitution significantly enhances the electrochemical and moisture stability of these solid electrolytes.