@article{26835,
  author = {Xiaosong Liu and Jun Liu and Ruimin Qiao and Yan Yu and Hong Li and Liumin Suo and Yong-sheng Hu and Yi- De Chuang and Guojiun Shu and Fangcheng Chou and Tsu-Chien Weng and Dennis Nordlund and Dimosthenis Sokaras and Yung J Wang and Hsin Lin and Bernardo Barbiellini and Arun Bansil and Xiangyun Song and Zhi Liu and Shishen Yan and Gao Liu and Shan Qjao and Thomas J Richardson and David G Prendergast and Zahid Hussain and Frank M.F de Groot and Wanli Yang},
  title = {Phase Transformation and Lithiation Effect on Electronic Structure of Li<sub>x</sub>FePO<sub>4</sub>: An In-Depth Study by Soft X-ray and Simulations},
  abstract = {<p>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.</p>},
  year = {2012},
  journal = {Journal of the American Chemical Society},
  volume = {134},
  pages = {13708-13715},
  month = {08/2012},
  isbn = {0002-7863},
  doi = {10.1021/ja303225e},
  language = {eng},
}