橄榄石
掺杂剂
材料科学
锂(药物)
离子
化学物理
无机化学
矿物学
结晶学
兴奋剂
化学
光电子学
医学
有机化学
内分泌学
作者
M. Saïful Islam,D. Driscoll,Craig A. J. Fisher,Peter R. Slater
摘要
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 energetics of a range of cations with charges varying from +2 to +5 are also examined. Low favorable energies are found only for divalent dopants on the Fe site (such as Mn), which is in accord with experimental work. Our results suggest that, on energetic grounds, LiFePO4 is not tolerant to aliovalent doping (e.g., Al, Ga, Zr, Ti, Nb, Ta) on either Li (M1) or Fe (M2) sites.
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