Interface Engineering for Constructing Air-Stable and Lithiophilic Garnet-Type Solid Electrolytes

Area of Science:

• Materials Science
• Electrochemistry
• Solid-State Chemistry

Background:

• Garnet-type solid electrolytes (SEs) are promising for solid-state Li metal batteries due to high ionic conductivity and electrochemical stability.
• Air sensitivity of garnet SEs leads to Li2CO3 formation, degrading interfacial properties and battery performance.

Purpose of the Study:

• To develop a strategy for enhancing the air stability and interfacial properties of garnet-type solid electrolytes.
• To improve the performance and cycle life of solid-state Li metal batteries.

Main Methods:

• Coating garnet SEs with Mg3(PO4)2 using a wet chemistry method.
• Thermal treatment to convert Li2CO3 into a Li3PO4/MgO composite layer.
• Electrochemical characterization including cycling stability and critical current density measurements.

Main Results:

• The Mg3(PO4)2 coating effectively converted Li2CO3 into a stable Li3PO4/MgO composite, ensuring air stability.
• The composite interface enhanced Li wettability and significantly reduced interfacial resistance.
• Achieved a high critical current density of 1.1 mA·cm-2 and stable cycling over 1200 hours.
• Demonstrated excellent cycling stability in full Li metal batteries with LiFePO4 and LiCoO2 cathodes.

Conclusions:

• The Li3PO4/MgO composite interface strategy effectively addresses the air sensitivity of garnet SEs.
• This modification strategy is practical and enhances the performance of solid-state Li metal batteries.