3 research outputs found
Phase Transformation and Lithiation Effect on Electronic Structure of LixFePO4 : An In-Depth Study by Soft X-ray and Simulations
Through soft X-ray absorption spectroscopy, hard X-ray Raman scattering, and theoretical simulations, we provide the most in-depth and systematic study of the phase transformation and (de)lithiation effect on electronic structure in LixFePO4 nanoparticles and single crystals. Soft X-ray reveals directly the valence states of Fe 3d electrons in the vicinity of Fermi level, which is sensitive to the local lattice distortion, but more importantly offers detailed information on the evolution of electronic states at different electrochemical stages. The soft X-ray spectra of LixFePO4 nanoparticles evolve vividly with the (de)lithiation level. The spectra fingerprint the (de)lithiation process with rich information on Li distribution, valency, spin states, and crystal field. The high resolution spectra reveal a subtle but critical deviation from two-phase transformation in our electrochemically prepared samples. In addition, we performed both first principles calculations and multiplet simulations of the spectra and quantitatively determined the 3d valence states that are completely redistributed through (de)lithiation. This electronic reconfiguration was further verified by the polarization-dependent spectra collected on LiFePO4 single crystals, especially along the lithium diffusion direction. The evolution of the 3d states is overall consistent with the local lattice distortion and provides a fundamental picture of the (de)lithiation effects on electronic structure in the LixFePO4 system
Phase Transformation and Lithiation Effect on Electronic Structure of Li<sub><i>x</i></sub>FePO<sub>4</sub>: An In-Depth Study by Soft X‑ray and Simulations
Through soft X-ray absorption spectroscopy, hard X-ray
Raman scattering,
and theoretical simulations, we provide the most in-depth and systematic
study of the phase transformation and (de)Âlithiation effect on electronic
structure in Li<sub><i>x</i></sub>FePO<sub>4</sub> nanoparticles
and single crystals. Soft X-ray reveals directly the valence states
of Fe 3d electrons in the vicinity of Fermi level, which is sensitive
to the local lattice distortion, but more importantly offers detailed
information on the evolution of electronic states at different electrochemical
stages. The soft X-ray spectra of Li<sub><i>x</i></sub>FePO<sub>4</sub> nanoparticles evolve vividly with the (de)Âlithiation level.
The spectra fingerprint the (de)Âlithiation process with rich information
on Li distribution, valency, spin states, and crystal field. The high-resolution
spectra reveal a subtle but critical deviation from two-phase transformation
in our electrochemically prepared samples. In addition, we performed
both first-principles calculations and multiplet simulations of the
spectra and quantitatively determined the 3d valence states that are
completely redistributed through (de)Âlithiation. This electronic reconfiguration
was further verified by the polarization-dependent spectra collected
on LiFePO<sub>4</sub> single crystals, especially along the lithium
diffusion direction. The evolution of the 3d states is overall consistent
with the local lattice distortion and provides a fundamental picture
of the (de)Âlithiation effects on electronic structure in the Li<sub><i>x</i></sub>FePO<sub>4</sub> system