Ultrafast sodium storage in anatase TiO<inf>2</inf> nanoparticles embedded on carbon nanotubes

Jang Yeon Hwang, Seung Taek Myung, Joo Hyeong Lee, Ali Abouimrane, Ilias Belharouak, Yang Kook Sun

Research output: Contribution to journalArticle

90 Citations (Scopus)


The main disadvantage of using transition metal oxides for Na<sup>+</sup>-ion batteries is the sluggish kinetics of insertion of Na<sup>+</sup> ions into the structure. Here, we introduce nanosized anatase TiO<inf>2</inf> that is partially doped with fluorine (TiO<inf>2-δ</inf>F<inf>δ</inf>) to form electro-conducting trivalent Ti<sup>3+</sup> as an ultrafast Na<sup>+</sup> insertion material for use as an anode for sodium-ion batteries. In addition, the F-doped TiO<inf>2-δ</inf>F<inf>δ</inf> is modified by electro-conducting carbon nanotubes (CNTs) to further enhance the electric conductivity. The composite F-doped TiO<inf>2</inf> embedded in CNTs is produced in a one-pot hydrothermal reaction. X-ray diffraction and microscopic studies revealed that nanocrystalline anatase-type TiO<inf>2-δ</inf>F<inf>δ</inf> particles, in which fluorine is present with TiO<inf>2</inf> particles, are loaded on the CNTs. This yields a high electric conductivity of approximately 5.8Scm<sup>-1</sup>. The first discharge capacity of the F-doped TiO<inf>2</inf> embedded in CNTs is approximately 250mAh (g-oxide)<sup>-1</sup>, and is retained at 97% after 100 cycles. As expected, a high-rate performance was achieved even at the 100C discharging rate (25Ag<sup>-1</sup>) where the composite material demonstrated a capacity of 118mAhg<sup>-1</sup> under the 0.1C-rate charge condition. The present work also highlights a significant improvement in the insertion and extraction of Na<sup>+</sup> ions when the material was charged and discharged under the same rate of 35C (8.75Ag<sup>-1</sup>), delivering approximately 90mAh (g-oxide)<sup>-1</sup>.

Original languageEnglish
Pages (from-to)218-226
Number of pages9
JournalNano Energy
Publication statusPublished - 1 Sep 2015



  • Anatase TiO<inf>2</inf>
  • Anode
  • Carbon nanotubes
  • Nanocrystalline
  • Sodium batteries

ASJC Scopus subject areas

  • Renewable Energy, Sustainability and the Environment
  • Materials Science(all)
  • Electrical and Electronic Engineering

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