Fast Lithium Ionic Conductivity in Complex Hydride-Sulfide Electrolytes by Double Anions Substitution

Area of Science:

• Materials Science
• Electrochemistry
• Solid-State Chemistry

Background:

• Hydride-based solid-state electrolytes (SSEs) offer good stability with lithium metal anodes.
• A significant hurdle for hydride SSEs is their low ionic conductivity at room temperature.
• Developing efficient SSEs is crucial for advancing solid-state lithium-ion batteries.

Purpose of the Study:

• To explore a novel hydride-based solid-state electrolyte with enhanced ionic conductivity.
• To investigate the effect of double anion substitution on the properties of LiBH4-LiI-P2S5 systems.
• To develop a practical material for room-temperature, fast-conducting solid-state batteries.

Main Methods:

• Synthesized a series of double anion substituted compounds: (100-x)(3LiBH4 -LiI)-xP2S5 (LLPx).
• Characterized ionic conductivity, electrochemical window, and stability of the synthesized materials.
• Performed lithium plating/stripping tests and evaluated all-solid-state cell performance.

Main Results:

• The LLP20 sample achieved an ionic conductivity of 3.77 × 10^-4 S cm^-1 at 30°C and 1.0 × 10^-2 S cm^-1 at 100°C.
• A stable electrochemical window of 0-5 V was observed.
• The material demonstrated excellent stability in Li plating/stripping tests (>1000 h) and good performance in all-solid-state cells across a wide temperature range.

Conclusions:

• Double anion substitution in (3LiBH4 -LiI)-LiI-P2S5 systems effectively enhances ionic conductivity.
• The developed LLP20 material is a promising candidate for fast ion conduction in solid-state lithium-ion batteries.
• This work presents a viable strategy for creating ambient-temperature, fast ionic conductors for future solid-state batteries.