Oxygen-Mediated Nanocrystalline-Amorphous LaCl3-Based Composite Electrolytes for All-Solid-State Lithium Batteries

Area of Science:

• Materials Science
• Electrochemistry
• Solid-State Chemistry

Background:

• Chlorine-based halide solid-state electrolytes (SSEs) are promising for all-solid-state lithium batteries (ASSLBs) due to high ionic conductivity and oxidative stability.
• LaCl3-based SSEs offer 1D transport channels but suffer from rigid pathways and grain boundary resistance, limiting practical application.

Purpose of the Study:

• To engineer LaCl3-based composite electrolytes with enhanced ionic conductivity and mechanical properties for ASSLBs.
• To investigate the structural modifications induced by dual-anion engineering via Li2O substitution.

Main Methods:

• Synthesis of a series of LaCl3-based composite electrolytes (LTLCO) by substituting LiCl with Li2O in Li0.388Ta0.238La0.475Cl3.
• Atomic and local structure analysis to understand element distribution and coordination.
• Electrochemical testing of ionic conductivity and ASSLB performance with NCM83 cathodes.

Main Results:

• Distinct local structural variations observed, with oxygen preferentially coordinating with Ta.
• Optimized SSE (Li0.35Ta0.25La0.5Cl2.75O0.175) achieved high ionic conductivity (2.05 mS cm-1 at 30 °C) and superior mechanical deformability.
• ASSLBs demonstrated exceptional rate performance and 83.4% capacity retention after 300 cycles.

Conclusions:

• Dual-anion engineering via Li2O substitution effectively modifies the local structure of LaCl3-based SSEs.
• The developed composite electrolytes mitigate interfacial failure and enhance ASSLB performance.
• This approach offers a promising strategy for developing next-generation solid-state batteries.