Orientation-Dependent Intercalation Channels for Lithium and Sodium in Black Phosphorus

Sungkyu Kim, Jiang Cui, Vinayak P. Dravid, Kai He*

*Corresponding author for this work

Research output: Contribution to journalArticle

5 Scopus citations

Abstract

Black phosphorus (BP) with unique 2D structure enables the intercalation of foreign elements or molecules, which makes BP directly relevant to high-capacity rechargeable batteries and also opens a promising strategy for tunable electronic transport and superconductivity. However, the underlying intercalation mechanism is not fully understood. Here, a comparative investigation on the electrochemically driven intercalation of lithium and sodium using in situ transmission electron microscopy is presented. Despite the same preferable intercalation channels along [100] (zigzag) direction, distinct anisotropic intercalation behaviors are observed, i.e., Li ions activate lateral intercalation along [010] (armchair) direction to form an overall uniform propagation, whereas Na diffusion is limited in the zigzag channels to cause the columnar intercalation. First-principles calculations indicate that the diffusion of both Li and Na ions along the zigzag direction is energetically favorable, while Li/Na diffusion long the armchair direction encounters an increased energy barrier, but that of Na is significantly larger and insurmountable, which accounts for the orientation-dependent intercalation channels. The evolution of chemical states during phase transformations (from LixP/NaxP to Li3P/Na3P) is identified by analytical electron diffraction and energy-loss spectroscopy. The findings elucidate atomistic Li/Na intercalation mechanisms in BP and show potential implications for other similar 2D materials.

Original languageEnglish (US)
Article number1904623
JournalAdvanced Materials
Volume31
Issue number46
DOIs
StatePublished - Nov 1 2019

Keywords

  • anisotropic intercalation channels
  • black phosphorus
  • in situ transmission electron microscopy
  • lithium-ion batteries
  • sodium-ion batteries

ASJC Scopus subject areas

  • Materials Science(all)
  • Mechanics of Materials
  • Mechanical Engineering

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