In Situ Formed Li-Ag Alloy Interface Enables Li₁₀GeP₂S₁₂-Based All-Solid-State Lithium Batteries

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• All-solid-state lithium-metal batteries (ASSLMBs) offer high energy density and safety but suffer from poor Li/solid electrolyte (SE) interface compatibility and lithium dendrite penetration.
• These interfacial issues hinder the commercialization of ASSLMBs, necessitating strategies to improve stability and performance.

Purpose of the Study:

• To investigate the effect of a thin silver (Ag) layer on the Li/SE interface in ASSLMBs.
• To tune interfacial chemistry and improve lithium deposition/dissolution behavior for enhanced electrochemical properties and cycle life.

Main Methods:

• A thin Ag layer was introduced between lithium metal and Li$_{10}$GeP$_{2}$S$_{12}$ solid electrolyte.
• In situ formation of a Li-Ag alloy interface was achieved by optimizing Ag layer thickness.
• Electrochemical properties were evaluated using symmetric cells and full cells, focusing on interfacial stability and cycling performance.

Main Results:

• Optimized Ag layer thickness (1 μm) resulted in a stable Li-Ag alloy interface, showing steady voltage evolution for over 1000 hours in a symmetric cell with 1 mAh cm^-2 areal capacity.
• The assembled ASSLMB demonstrated a high reversible capacity of 106.5 mAh g^-1 after 100 cycles, validating the effectiveness of the Ag interlayer.
• Improved interfacial stability and lithium deposition/dissolution behavior were observed with the Ag modification.

Conclusions:

• The introduction of a thin Ag layer is a viable strategy for re-engineering the Li/SE interface in ASSLMBs.
• The Li-Ag alloy interface effectively enhances interfacial compatibility, suppresses lithium dendrites, and significantly improves the cycle life of ASSLMBs.
• This work provides a novel approach for developing next-generation high-performance and safe all-solid-state batteries.