Charge Heterogeneity and Surface Chemistry in Polycrystalline Cathode Materials

Charge Heterogeneity and Surface Chemistry in Polycrystalline Cathode Materials

TitleCharge Heterogeneity and Surface Chemistry in Polycrystalline Cathode Materials
Publication TypeJournal Article
Year of Publication2018
AuthorsChixia Tian, Yahong Xu, Dennis Nordlund, Feng Lin, Jin Liu, Zhihong Sun, Yijin Liu, Marca M Doeff
JournalJoule
Volume2
Issue3
Pagination464 - 477
Date Published03/2018
ISSN25424351
Abstract

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 LiNi0.6Mn0.2Co0.2O2 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.

DOI10.1016/j.joule.2017.12.008
Short TitleJoule
Refereed DesignationRefereed