LaCl₃-based sodium halide solid electrolytes with high ionic conductivity for all-solid-state batteries

Area of Science:

• Materials Science
• Electrochemistry
• Solid-State Chemistry

Background:

• High-performance all-solid-state batteries require catholytes with excellent ionic conductivity, compressibility, and oxidative stability.
• Current limitations in catholyte materials hinder the efficiency and longevity of solid-state energy storage devices.

Purpose of the Study:

• To synthesize and characterize a novel LaCl3-based Na+ superionic conductor for use as a catholyte in all-solid-state batteries.
• To investigate the structural and ionic transport properties of the synthesized material and its impact on battery performance.

Main Methods:

• Solid-state reaction combined with mechanochemical methods for material synthesis.
• X-ray diffraction (XRD) for structural analysis.
• First-principle calculations and X-ray absorption fine structure (XAFS) for understanding ionic conductivity mechanisms.

Main Results:

• A hexagonal Na1-xZrxLa1-xCl4 phase with high ionic conductivity (2.9 × 10-4 S cm-1 at 30°C) and high oxidative potential (3.80 V vs. Na2Sn) was successfully prepared.
• Na+ ions form one-dimensional diffusion channels along the c-axis, with conductivity influenced by channel size and Na+/La3+ mixing.
• All-solid-state batteries utilizing this material as a catholyte demonstrated an initial capacity of 114 mAh g-1 and 88% retention over 70 cycles at 0.3 C.

Conclusions:

• The synthesized LaCl3-based Na+ superionic conductor exhibits promising properties for high-performance all-solid-state batteries.
• The material's structure and ionic transport mechanisms are well-defined, offering a pathway for further optimization.
• The demonstrated battery performance indicates the potential of this material for practical energy storage applications.