Kinetic Phase Evolution of Spinel Cobalt Oxide during Lithiation

Jing Li, Kai He, Qingping Meng, Xin Li, Yizhou Zhu, Sooyeon Hwang, Ke Sun, Hong Gan, Yimei Zhu, Yifei Mo, Eric A. Stach, Dong Su*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

30 Scopus citations

Abstract

Spinel cobalt oxide has been proposed to undergo a multiple-step reaction during the electrochemical lithiation process. Understanding the kinetics of the lithiation process in this compound is crucial to optimize its performance and cyclability. In this work, we have utilized a low-angle annular dark-field scanning transmission electron microscopy method to visualize the dynamic reaction process in real time and study the reaction kinetics at different rates. We show that the particles undergo a two-step reaction at the single-particle level, which includes an initial intercalation reaction followed by a conversion reaction. At low rates, the conversion reaction starts after the intercalation reaction has fully finished, consistent with the prediction of density functional theoretical calculations. At high rates, the intercalation reaction is overwhelmed by the subsequently nucleated conversion reaction, and the reaction speeds of both the intercalation and conversion reactions are increased. Phase-field simulations show the crucial role of surface diffusion rates of lithium ions in controlling this process. This work provides microscopic insights into the reaction dynamics in non-equilibrium conditions and highlights the effect of lithium diffusion rates on the overall reaction homogeneity as well as the performance.

Original languageEnglish (US)
Pages (from-to)9577-9585
Number of pages9
JournalACS nano
Volume10
Issue number10
DOIs
StatePublished - Oct 25 2016

Keywords

  • CoO nanoparticles
  • in situ TEM
  • lithium-ion battery

ASJC Scopus subject areas

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

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