Stable Anode-Free All-Solid-State Lithium Battery through Tuned Metal Wetting on the Copper Current Collector.

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• Anode-free all-solid-state batteries (AF-ASSBs) offer high energy density but face challenges with lithium metal plating and stripping.
• Achieving stable cycling in AF-ASSBs requires uniform lithium deposition and dissolution on the current collector.

Purpose of the Study:

• To develop a stable AF-ASSB by improving the lithiophilicity of the copper current collector.
• To investigate the effect of a lithiophilic coating on lithium metal behavior during battery cycling.

Main Methods:

• Synthesis of a lithiophilic Li₂ Te coating on a copper current collector via tellurium vapor exposure.
• In situ lithium activation during the first charge cycle.
• Electrochemical characterization using half-cells and full AF-ASSBs with NMC811 cathodes.
• Cryogenic focused ion beam (Cryo-FIB) for microstructural analysis.
• Density functional theory (DFT) and mesoscale calculations.

Main Results:

• The Li₂ Te coating significantly reduced electrodeposition/electrodissolution overpotentials and improved Coulombic efficiency (CE).
• Over 70 µm of lithium metal was continuously electrodeposited on the Li₂ Te-coated copper collector with uniform microstructure and no dendrites.
• Full AF-ASSBs demonstrated an initial CE of 83% at 0.2C and cycling CE above 99%.
• Unmodified copper collectors showed inhomogeneous lithium deposition, dendrite formation, and unstable solid electrolyte interphase (SEI).

Conclusions:

• Tuning current collector lithiophilicity is crucial for stable AF-ASSB operation.
• The Li₂ Te coating promotes uniform lithium plating/stripping, enhancing battery stability and cycle life.
• This approach offers a promising strategy for advancing high-performance solid-state batteries.