LixFeF6 (x = 2, 3, 4) Battery Materials: Structural, Electronic and Lithium Diffusion Properties Presentation Format: Poster

Lithium iron fluoride materials have attracted recent interest as cathode materials for lithium ion batteries. The electrochemical properties of the high energy density Li_xFeF₆ (x = 2, 3, 4) materials have been evaluated using a combination of potentials-based and DFT computational methods. Voltages of 6.1V and 3.0V are found for lithium intercalation from Li₂FeF₆ to α-Li₃FeF₆ and α-Li₃FeF₆ to Li₄FeF₆ respectively. The calculated density of states indicate that Li₂FeF₆ possesses metallic states that become strongly insulating after lithium intercalation to form α-Li₃FeF₆. The large energy gain associated with this metal-insulator transiton is likely to contribute to the associated large voltage of 6.1 V. Molecular dynamics simulations of lithium diffusion in α-Li₃FeF₆ at typical battery operating temperatures indicate high lithium-ion mobility with low activation barriers. These results suggest the potential for good rate performance for lithium iron fluoride cathode materials[1].

[1] M. Schroeder, C. Eames, D. A. Tompsett, G. Lieser, M. S. Islam, Phys. Chem. Chem. Phys., 2013, 15, 20473.