Science Advances

Supplementary Materials

This PDF file includes:   

  • Legends for movies S1 to S3

  • fig. S1. Morphology and structure of FP and LFP nanoparticles.

  • fig. S2. Electrochemical performance of FP nanoparticles tested in regular coin cells.

  • fig. S3. A bright-field TEM image showing a single-crystalline FP nanoparticle (in the central region), being tilted to [010] direction for in situ ED measurements (Fig. 2).

  • fig. S4. The evolution of ED intensity profiles of diffraction spot (001) versus distance from the central spot (000), shown with original data (dots), and fitted ones (solid lines) by weighted Gaussian and Lorentzian functions.

  • fig. S5. Electron energy loss spectra of Fe-L2,3 and O-K edges from the FP nanoparticle (shown in fig. S3) before and after lithiation during in situ ED measurements.

  • fig. S6. HRTEM images from a single particle (oriented along [010]) during lithiation (as in Fig. 3) taken at different times.

  • fig. S7. Evolution of intensity profiles of (100) and (001) diffraction spots in the FFT patterns obtained from the HRTEM images in fig. S6, in comparison to that obtained from in situ ED measurements.

  • fig. S8. Local lattice displacement in FP due to lithiation.

  • fig. S9. Intensity profiles of the Li concentration distribution showing continuous variation of the Li concentration between the neighboring Li-rich and Li-poor regions.

  • fig. S10. Evolution of Li concentration averaged at the lower left and upper left corners of region B in Fig. 3 (B to I).

  • fig. S11. Synchrotron XRD patterns in comparison to that obtained by Rietveld refinements, from pristine LFP, chemically delithiated FP, and electrochemically lithiated LFP.

  • fig. S12. Inhomogeneity of anti-site defects within the electrochemically lithiated nanoparticles (LFP).

  • fig. S13. Calculated strain energy density on the surface of the particle and on the a-c plane at the center of the particle.

  • fig. S14. Evolution of averaged Li concentration over different sampling sizes (as labeled with domains 1 and 2 in Fig. 5B), with low and high anisotropic ratios of Li mobility along the three crystalline directions.

  • note S1. Nonuniformly distributed anti-site defects in LFP

  • note S2. Concentration reversal in local regions within different anisotropic ratio of Li mobility along the three crystalline directions

  • References (54, 55)
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  • Movie S1 -

    An in situ TEM movie showing the evolution of the ED patterns projected along the [010] direction.

  • Movie S2 -

    A simulation movie showing the evolution of projected Li concentration along the [010] direction.

  • Movie S3 -

    A 3D view movie showing the evolution of simulated Li concentration distribution in different local regions.