Understanding the Role of Overpotentials in Lithium Ion Conversion Reactions: Visualizing the Interface

Guennadi Evmenenko, Robert E. Warburton, Handan Yildirim, Jeffrey P. Greeley, Maria K.Y. Chan, D. Bruce Buchholz, Paul Fenter, Michael J. Bedzyk, Timothy T. Fister*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

4 Scopus citations

Abstract

Oxide conversion reactions are known to have substantially higher specific capacities than intercalation materials used in Li-ion batteries, but universally suffer from large overpotentials associated with the formation of interfaces between the resulting nanoscale metal and Li2O products. Here we use the interfacial sensitivity of operando X-ray reflectivity to visualize the structural evolution of ultrathin NiO electrodes and their interfaces during conversion. We observe two additional reactions prior to the well-known bulk, three-dimensional conversion occurring at 0.6 V: an accumulation of lithium at the buried metal/oxide interface (at 2.2 V) followed by interfacial lithiation of the buried NiO/Ni interface at the theoretical potential for conversion (at 1.9 V). To understand the mechanisms for bulk and interfacial lithiation, we calculate interfacial energies using density functional theory to build a potential-dependent nucleation model for conversion. These calculations show that the additional space charge layer of lithium is a crucial component for reducing energy barriers for conversion in NiO.

Original languageEnglish (US)
Pages (from-to)7825-7832
Number of pages8
JournalACS nano
Volume13
Issue number7
DOIs
StatePublished - Jul 23 2019

Keywords

  • battery
  • interfaces
  • nucleation
  • reflectivity
  • reflectometry

ASJC Scopus subject areas

  • Materials Science(all)
  • Engineering(all)
  • Physics and Astronomy(all)

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