Atomic-Scale Investigation of Defects, Dopants, and Lithium Transport in the LiFePO 4 Olivine-Type Battery Material

Key issues relating to intrinsic defects, dopant incorporation, and lithium ion migration in the LiFePO4 electrode material have been investigated using well-established atomistic modeling techniques. Our simulation model shows good reproduction of the observed olivine-type structure of LiFePO4. The most favorable intrinsic defect is the Li−Fe “anti-site” pair in which a Li ion (on the M1 site) and an Fe ion (on the M2 site) are interchanged. This type of anti-site defect or “intersite exchange” has been observed in olivine silicates. The lowest Li migration energy is found for the pathway along the [010] channel, with a nonlinear, curved trajectory between adjacent Li sites. Trends in dopant substitution…