Atomic Insights into the Enhanced Surface Stability in High Voltage Cathode Materials by Ultrathin Coating

Xin Fang, Feng Lin, Dennis Nordlund, Matthew Mecklenburg, Mingyuan Ge, Jiepeng Rong, Anyi Zhang, Chenfei Shen, Yihang Liu, Yu Cao, Marca M. Doeff, Chongwu Zhou

Research output: Contribution to journalArticle

17 Scopus citations

Abstract

Surface properties of electrode materials play a critical role in the function of batteries. Therefore, surface modifications, such as coatings, have been widely used to improve battery performance. Understanding how these coatings function to improve battery performance is crucial for both scientific research and applications. In this study the electrochemical performance of coated and uncoated LiNi0.5Mn1.5O4 (LNMO) electrodes is correlated with ensemble-averaged soft X-ray absorption spectroscopy (XAS) and spatially resolved scanning transmission electron microscopy-electron energy loss spectroscopy (STEM-EELS) to illustrate the mechanism of how ultrathin layer Al2O3 coatings improve the cycle life of LiNi0.5Mn1.5O4. Mn2+ evolution on the surface is clearly observed in the uncoated sample, which results from the reaction between the electrolytic solution and the surfaces of LiNi0.5Mn1.5O4 particles, and also possibly atomic structure reconstructions and oxygen loss from the surface region in LiNi0.5Mn1.5O4. The coating effectively suppresses Mn2+ evolution and improves the battery performance by decelerating the impedance buildup from the surface passivation. This study demonstrates the importance of combining ensemble-averaged techniques (e.g., XAS) with localized techniques (e.g., STEM-EELS), as the latter may yield unrepresentative information due to the limited number of studied particles, and sheds light on the design of future coating processes and materials.

Original languageEnglish (US)
Article number1602873
JournalAdvanced Functional Materials
Volume27
Issue number7
DOIs
StatePublished - Feb 17 2017

Keywords

  • LiNiMnO
  • Mn evolution
  • high voltage cathodes
  • lithium ion batteries
  • surface modifications

ASJC Scopus subject areas

  • Chemistry(all)
  • Materials Science(all)
  • Condensed Matter Physics

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    Fang, X., Lin, F., Nordlund, D., Mecklenburg, M., Ge, M., Rong, J., Zhang, A., Shen, C., Liu, Y., Cao, Y., Doeff, M. M., & Zhou, C. (2017). Atomic Insights into the Enhanced Surface Stability in High Voltage Cathode Materials by Ultrathin Coating. Advanced Functional Materials, 27(7), [1602873]. https://doi.org/10.1002/adfm.201602873