Mitigating Interfacial Mismatch between Lithium Metal and Garnet-Type Solid Electrolyte by Depositing Metal Nitride...

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• Solid-state lithium batteries are promising next-generation energy storage devices due to their nonflammable solid electrolytes and potential for high-capacity lithium metal anodes.
• Cubic garnet-type Li7La3Zr2O12 ceramics offer high ionic conductivity and chemical stability, making them suitable solid electrolytes.
• Interfacial challenges, including high impedance and uneven current distribution between lithium metal and garnet electrolytes, hinder practical solid-state battery applications.

Purpose of the Study:

• To develop a facile and effective strategy for reducing interfacial mismatch in garnet-based solid-state lithium batteries.
• To improve the interfacial contact and electrochemical performance between lithium metal anodes and garnet solid electrolytes.
• To demonstrate the viability of silicon nitride (Si3N4) as an interfacial modification layer for garnet solid electrolytes.

Main Methods:

• Surface modification of cubic garnet-type Li7La3Zr2O12 solid electrolytes with a thin layer of silicon nitride (Si3N4).
• Fabrication and testing of lithium symmetrical cells using bare and Si3N4-modified garnet electrolytes.
• Assembly and electrochemical evaluation of a hybrid solid-state battery utilizing Si3N4-modified garnet with a LiFePO4 cathode and lithium metal anode.

Main Results:

• The Si3N4 interfacial layer ensured intimate contact with lithium metal through lithiophilic properties and intermediate alloy formation.
• Interfacial resistance was dramatically reduced from 1197 to 84.5 Ω cm² after Si3N4 modification.
• Lithium symmetrical cells with Si3N4-modified garnet showed low overpotential and stable plating/stripping cycles at room temperature.
• A hybrid solid-state battery demonstrated high cycling efficiency, excellent rate capability, and good electrochemical stability.

Conclusions:

• Silicon nitride (Si3N4) surface modification is a highly effective strategy for mitigating interfacial issues in garnet solid electrolytes.
• The improved interfacial properties enable stable and efficient lithium metal plating/stripping, crucial for solid-state battery operation.
• This advancement paves the way for the practical application of garnet solid electrolytes in high-performance lithium metal batteries for next-generation energy storage.