Sodiation Kinetics of Metal Oxide Conversion Electrodes: A Comparative Study with Lithiation

Kai He, Feng Lin, Yizhou Zhu, Xiqian Yu, Jing Li, Ruoqian Lin, Dennis Nordlund, Tsu Chien Weng, Ryan M. Richards, Xiao Qing Yang, Marca M. Doeff, Eric A. Stach, Yifei Mo*, Huolin L. Xin, Dong Su

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

82 Scopus citations


The development of sodium ion batteries (NIBs) can provide an alternative to lithium ion batteries (LIBs) for sustainable, low-cost energy storage. However, due to the larger size and higher m/e ratio of the sodium ion compared to lithium, sodiation reactions of candidate electrodes are expected to differ in significant ways from the corresponding lithium ones. In this work, we investigated the sodiation mechanism of a typical transition metal-oxide, NiO, through a set of correlated techniques, including electrochemical and synchrotron studies, real-time electron microscopy observation, and ab initio molecular dynamics (MD) simulations. We found that a crystalline Na2O reaction layer that was formed at the beginning of sodiation plays an important role in blocking the further transport of sodium ions. In addition, sodiation in NiO exhibits a shrinking-core mode that results from a layer-by-layer reaction, as identified by ab initio MD simulations. For lithiation, however, the formation of Li antisite defects significantly distorts the local NiO lattice that facilitates Li insertion, thus enhancing the overall reaction rate. These observations delineate the mechanistic difference between sodiation and lithiation in metal-oxide conversion materials. More importantly, our findings identify the importance of understanding the role of reaction layers on the functioning of electrodes and thus provide critical insights into further optimizing NIB materials through surface engineering.

Original languageEnglish (US)
Pages (from-to)5755-5763
Number of pages9
JournalNano letters
Issue number9
StatePublished - Sep 9 2015


  • Sodiation
  • conversion electrodes
  • in situ TEM
  • kinetics
  • nickel oxides
  • reaction pathways

ASJC Scopus subject areas

  • Bioengineering
  • Chemistry(all)
  • Materials Science(all)
  • Condensed Matter Physics
  • Mechanical Engineering


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