A LaCl₃-based lithium superionic conductor compatible with lithium metal

Area of Science:

• Materials Science
• Electrochemistry
• Solid-State Chemistry

Background:

• Inorganic superionic conductors offer high ionic conductivity and thermal stability.
• Poor interfacial compatibility with lithium metal anodes hinders their use in solid-state lithium metal batteries.

Purpose of the Study:

• To develop a LaCl3-based lithium superionic conductor with improved interfacial compatibility for lithium metal anodes.
• To investigate the ionic conductivity and electrochemical stability of the new electrolyte.

Main Methods:

• Synthesized a UCl3-type LaCl3 lattice doped with Ta to create vacancies.
• Investigated Li+ conduction pathways and electrochemical properties.
• Fabricated and tested Li-Li symmetric cells and full solid-state batteries.

Main Results:

• The optimized Li0.388Ta0.238La0.475Cl3 electrolyte exhibits high Li+ conductivity (3.02 mS cm-1 at 30°C) and low activation energy (0.197 eV).
• Demonstrated excellent interfacial compatibility with Li metal, forming a gradient passivation layer.
• Achieved stable cycling in Li-Li symmetric cells for over 5,000 hours and in a full solid-state battery for over 100 cycles.

Conclusions:

• The LaCl3-based electrolyte offers a promising solution for stable solid-state lithium metal batteries.
• The UCl3-type structure and Ta doping facilitate a 3D Li+ migration network.
• Lanthanide metal chlorides show potential for further advancements in solid electrolyte development.