First-principles study of the chemical bonding and conduction behavior of LiFePO4

The electronic structure and chemical bonding of LiFePO4 were calculated using maximally-localized Wannier functions within the framework of the first-principles method. Comparison of the shifts in Wannier centers between LiFePO4 and delithiated reference (FePO4)(r) structures demonstrated the unstable chemical bonding of Fe-O1 and Fe-O2 during delithiation. The contribution of each orbital to the small-polaron polarization field was discussed in detail. The small polaron hopping is accompanied by a very small polarization field with the value of 0.049 C/m(2). Results of our calculations showed that the chemical bonding of Fe-O3 has an important function in the low-temperature conductivity of LiFePO4. (C) 2014 Elsevier B.V. All rights reserved.