Morphological reason for enhancement of electrochemical double layer capacitances of various acetylene blacks by electrochemical polarization

Taegon Kim, Chulho Ham, Choong Kyun Rhee, Seong Ho Yoon, Masaharu Tsuji, Isao Mochida

Research output: Contribution to journalArticle

10 Citations (Scopus)

Abstract

Enhancement of electrochemical capacitance and morphological variations of various acetylene blacks caused by electrochemical polarization are presented. Acetylene blacks of different mean particle diameters were modified by air-oxidation and heat treatment to diversify the morphologies of the acetylene blacks before electrochemical polarization. The various acetylene blacks were electrochemically oxidized at 1.6 V (vs. Ag/AgCl) for 10 s and the polarization step was repeated until the capacitance values did not change any longer. These polarization steps enhanced the capacitances of the acetylene blacks and the specific enhancement factors range from 2 to 5.5. Such an enhancement is strongly related to morphological modification as revealed by transmission electron microscopic observations. The electrochemical polarization resulted in formation of tiny graphene sheets on the wide graphitic carbon surfaces, which were most responsible for the observed capacitive enhancement. Although the pseudo-capacitance increased after polarization by forming oxygenated species on the surfaces, its contribution to the total capacitance was less than 10%. The mechanism of the formation of the tiny graphene sheets during the electrochemical oxidation is described schematically.

Original languageEnglish
Pages (from-to)5789-5795
Number of pages7
JournalElectrochimica Acta
Volume53
Issue number19
DOIs
Publication statusPublished - Aug 1 2008

All Science Journal Classification (ASJC) codes

  • Chemical Engineering(all)
  • Electrochemistry

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