Lithium-Rich Antifluorite Li₅Fe_xAl_1-xO₄: Phase-Controllable Syntheses, Local Structural Evolution, and...

Area of Science:

• Materials Science
• Electrochemistry
• Solid-State Chemistry

Background:

• Lithium-rich antifluorite oxides are crucial cathode prelithiation materials.
• Understanding structure-performance relationships is key for optimizing these materials.

Purpose of the Study:

• To investigate the impact of Fe-Al substitution on Li5AlO4 and Li5FeO4 solid solutions.
• To establish a direct link between local/electronic structure and electrochemical activity.

Main Methods:

• Formation of continuous (α-Li5FexAl1-xO4) and phase transition (β-Li5FexAl1-xO4) solid solutions.
• Analysis of local coordination and electronic structure changes.
• Electrochemical performance evaluation of the synthesized materials.

Main Results:

• In α-phase solid solutions, structural changes in FeO4 polyhedra correlated with decreased electrochemical activity and battery capacity.
• In β-phase solid solutions, a phase transition at x=0.5 enhanced Li-Fe interaction, leading to loss of delithiation performance.
• A direct correlation was found between local/electronic structure and electrochemical activity.

Conclusions:

• The study provides a theoretical basis for designing high-performance prelithiation agents.
• Structural and electronic modifications significantly influence the electrochemical behavior of lithium-rich antifluorite oxides.
• Rational design of cathode materials requires a deep understanding of their fundamental properties.