Suppression of FeLi• antisite defects in fluorine-doped LiFePO4

We report on the suppression of FeLi• antisite defects in LiFe(PO4)1−xF3x with 0 ⩽ x ⩽ 0.4 prepared by sol–gel and hydrothermal methods. Evidence for a systematic suppression of antisite defects upon fluorine doping in LiFePO4 is inferred from Fourier transform infrared spectra, wherein a noticeable red shift in the symmetric P–O stretching vibrational mode of (PO4)3− polyanion from 970 to 957 cm−1 was observed. We report detailed structural and compositional studies of LiFe(PO4)1−xF3x, and discuss the implications for the performance of LiFePO4 cathodes in lithium ion batteries.

Graphical abstractFeLi• antisite defects are systematically suppressed by fluorine doping in LiFePO4 as evidenced from red shift of symmetric P–O stretching vibrational mode of (PO4)3− polyanion in FTIR spectra.Figure optionsDownload full-size imageDownload high-quality image (86 K)Download as PowerPoint slide