Structural and Electronic Properties of Li-Ion Battery Cathode Material FeF3

A new type of cathode materials for Li-ion batteries has been explored recently based on FeF3 in an attempt to raise the energy density and discharge voltage. In this work, the structural and electronic properties of cathode materials FeF3, for lithium ion batteries have been studied by the first-principles calculations within both the generalized gradient approximation (GGA) and GGA+U frameworks. Our results show that the antiferromagnetic configuration of FeF3 is more stable than the ferromagnetic one, which is consistent with experiments. An analysis of the electronic density of states shows that FeF3 is a Mott-Hubbard insulator with a large d-d type band gap. Additionally, a small spin polarization was found on F, consistent with a fluorin-mediated superexchange mechanism for the Fe-Fe magnetic interaction.