UCl₃-Type Crystalline Oxychloride Electrolytes for All-Solid-State Lithium-Ion Batteries.

Area of Science:

• Materials Science
• Electrochemistry
• Solid-State Chemistry

Background:

• Halide solid-state electrolytes are key for advanced lithium-ion batteries.
• Nonclose-packed frameworks, like UCl3-type structures, offer improved lithium-ion transport over traditional close-packed structures.
• Developing novel electrolytes is crucial for enhancing battery safety and performance.

Purpose of the Study:

• To synthesize and characterize a new family of UCl3-type crystalline oxychloride electrolytes (LLTCO).
• To investigate the effect of oxygen incorporation on ionic conductivity, electrochemical stability, and mechanical properties.
• To evaluate the performance of these electrolytes in all-solid-state lithium-ion batteries.

Main Methods:

• Rapid high-energy shake milling for synthesis of Li0.388+xLa0.475Ta0.238Cl3-xOx (LLTCO).
• Electrochemical impedance spectroscopy to measure ionic conductivity.
• Cyclic voltammetry to determine electrochemical stability.
• Li-Li symmetric cell testing to assess cycle life and dendrite suppression.
• Spectroscopy (e.g., XRD, XPS) to analyze material structure and composition.

Main Results:

• Optimized LLTCO (x=0.15) achieved ionic conductivity >2 mS cm-1 at 30 °C.
• Electrolytes demonstrated oxidative stability >5 V vs Li/Li+ and good mechanical compressibility.
• LLTCO-based cells exhibited long cycle life, suppressing lithium dendrite formation.
• Oxygen incorporation, substituting Cl- around Ta5+, enhanced Li+ dynamics without compromising crystallinity.
• All-solid-state batteries with LLTCO showed improved reversible capacities with Ni-rich cathodes.

Conclusions:

• Nonclose-packed UCl3-type oxychloride electrolytes offer a promising pathway for high-performance all-solid-state batteries.
• Oxygen incorporation is an effective strategy to enhance ionic conductivity and stability in these materials.
• LLTCO electrolytes demonstrate potential for safer and more efficient next-generation energy storage solutions.