Silver exsolution from Li-argyrodite electrolytes for initially anode-free all-solid-state batteries

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• All-solid-state batteries (ASSBs) offer enhanced safety but face challenges in achieving stable cycling, particularly in anode-free configurations.
• Non-uniform lithium (de)plating remains a critical issue, hindering practical application under operational conditions.

Purpose of the Study:

• To develop a strategy for uniform lithium deposition and stripping in initially anode-free ASSBs.
• To improve the cyclability and energy density of Li-argyrodite based solid-state batteries.

Main Methods:

• A bilayer electrolyte was designed, consisting of a silver (Ag)-doped Li-argyrodite layer adjacent to an undoped Li-argyrodite layer.
• Electrochemical exsolution of Ag+ from the doped layer was utilized to form lithiophilic silver seeds.
• These seeds facilitated uniform lithium plating and returned to the electrolyte upon stripping.

Main Results:

• The silver seeds induced uniform lithium plating and stripping, significantly enhancing reversibility during cycling.
• A pouch-type full-cell achieved a volumetric energy density of 1312 Wh/L and an areal discharge capacity of 7.0 mAh/cm² at 0.7 mA/cm².
• Stable cycling was demonstrated at a practical stack pressure of 2.0 MPa.

Conclusions:

• Electrochemical exsolution of Ag+ in Li-argyrodite solid electrolytes is an effective strategy for robust, high-energy-density initially anode-free ASSBs.
• The developed bilayer electrolyte promotes stable lithium metal cycling, overcoming key limitations in current ASSB technology.