@article{31876,
  author = {Chixia Tian and Yahong Xu and Dennis Nordlund and Feng Lin and Jin Liu and Zhihong Sun and Yijin Liu and Marca M Doeff},
  title = {Charge Heterogeneity and Surface Chemistry in Polycrystalline Cathode Materials},
  abstract = {<p>Nanoscale full-field (FF) transmission X-ray microscopy (TXM) and ensemble-averaged soft X-ray absorption spectroscopy (soft XAS) were used to investigate state-of-charge (SOC) heterogeneities in electrochemically charged or discharged and chemically oxidized samples of LiNi<sub>0.6</sub>Mn<sub>0.2</sub>Co<sub>0.2</sub>O<sub>2</sub> cathode materials. We observed considerable and similar non-uniformities in terms of Ni oxidation states (and, by proxy, lithium distributions) for all the samples in the bulk. Therefore, the chemically delithiated samples are similar to the electrochemically charged samples in terms of mesoscale charge heterogeneity in large polycrystalline particle ensembles. However, the gradient oxidation states of transition metals on the surface, which is partly responsible for the electrode degradation mechanism known as surface reconstruction, is much less apparent in chemically delithiated samples.</p>},
  year = {2018},
  journal = {Joule},
  volume = {2},
  pages = {464 - 477},
  month = {03/2018},
  issn = {25424351},
  doi = {10.1016/j.joule.2017.12.008},
  language = {eng},
}