Enhanced Electrochemical Performance of Ultracentrifugation-Derived nc-Li3VO4/MWCNT Composites for Hybrid Supercapacitors

Etsuro Iwama, Nozomi Kawabata, Nagare Nishio, Kazuaki Kisu, Junichi Miyamoto, Wako Naoi, Patrick Rozier, Patrice Simon, Katsuhiko Naoi

Research output: Contribution to journalArticlepeer-review

43 Citations (Scopus)

Abstract

Nanocrystalline Li3VO4 dispersed within multiwalled carbon nanotubes (MWCNTs) was prepared using an ultracentrifugation (uc) process and electrochemically characterized in Li-containing electrolyte. When charged and discharged down to 0.1 V vs Li, the material reached 330 mAh g-1 (per composite) at an average voltage of about 1.0 V vs Li, with more than 50% capacity retention at a high current density of 20 A g-1. This current corresponds to a nearly 500C rate (7.2 s) for a porous carbon electrode normally used in electric double-layer capacitor devices (1C = 40 mA g-1 per activated carbon). The irreversible structure transformation during the first lithiation, assimilated as an activation process, was elucidated by careful investigation of in operando X-ray diffraction and X-ray absorption fine structure measurements. The activation process switches the reaction mechanism from a slow "two-phase" to a fast "solid-solution" in a limited voltage range (2.5-0.76 V vs Li), still keeping the capacity as high as 115 mAh g-1 (per composite). The uc-Li3VO4 composite operated in this potential range after the activation process allows fast Li+ intercalation/deintercalation with a small voltage hysteresis, leading to higher energy efficiency. It offers a promising alternative to replace high-rate Li4Ti5O12 electrodes in hybrid supercapacitor applications.

Original languageEnglish
Pages (from-to)5398-5404
Number of pages7
JournalACS Nano
Volume10
Issue number5
DOIs
Publication statusPublished - 2016 May 24
Externally publishedYes

Keywords

  • LiVO
  • hyperdispersion
  • initial electrochemical activation
  • ultracentrifugation
  • ultrafast charge storage
  • varied energy efficiency

ASJC Scopus subject areas

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

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