Phase Evolution of Trirutile Li_0.5FeF₃ for Lithium-Ion Batteries

Extensive studies on trirutile Li0.5FeF3 phase have been commissioned in the context of Li–Fe–F system for Li-ion batteries. However, progress electrochemical and structural has greatly encumbered by low reactivity this material. In order to advance class materials, a comprehensive study into mechanisms is necessary. Therefore, herein, we report first time overall reaction ordered at elevated temperatures 90 °C with aid thermally stable ionic liquid electrolyte. Ordered prepared high-energy ball milling combined heat treatment followed tests, X-ray diffraction, absorption spectroscopic analyses. Our results reveal that reversible topotactic Li+ extraction/insertion from/into structure occurs two-phase minor volume change (1.09% between Li0.11FeF3) voltage range 3.2–4.3 V. The extension lower cutoff 2.5 V conversion LiF rutile FeF2 during discharging. subsequent charge triggers formation disordered 4.3 without showing reconversion from or FeF3.