Revisiting the carbon mesopore contribution towards improved performance of ionic liquid–based EDLCs at sub-zero temperatures

V. Pavlenko, S. Kalybekkyzy, Daniel Knez, Qamar Abbas*, Z. Mansurov, Zh. Bakenov, A. Ng*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

Abstract

The important role of mesopores has been investigated in electric double-layer capacitors (EDLCs) operating from 24 °C down to − 40 °C by using two in-house synthesized carbons with hierarchical porosity. These carbons were prepared from colloidal nanoparticles of SiO2 as the template and D-glucose as the carbon source. A decrease in the average diameter of the nanoparticles from 12 to 8 nm results in increased surface area and offers a perfect match between ions of binary mixture of imidazolium-based fluorinated ionic liquids and the pores of carbon. Short-range graphene layers produced with 8-nm silica nanoparticles lead to the creation of transport channels which better accommodate ions. We explain these findings per coulombic interactions among the ions and between the pore wall and the ionic species under confinement and electrochemical polarization conditions. Further, it is shown that a microporous carbon (another in-house produced rice-husk carbon SBET = 1800 m2∙g−1) performs better than hierarchical carbons at room temperature; however, thanks to the large fraction of mesopores, the latter exhibit far higher capacitance down to − 40 °C. While the ordering of ions in confinement is more critical at room temperature and dictated by the micropores, low temperature performance of supercapacitors is determined by the mesopores that provide channels for facile ion movement and keep the bulk ionic liquid–like properties.
Original languageEnglish
Pages (from-to)893-901
Number of pages9
JournalIonics
Volume28
Issue number2
Early online date6 Nov 2021
DOIs
Publication statusPublished - Feb 2022

Keywords

  • Hierarchical carbon
  • Ionic liquid
  • Template carbon
  • Pore size
  • Ion size
  • supercapacitor
  • Electric double layer
  • SiO -templated carbon
  • Coulombic ordering
  • Mesopore
  • Electric double-layer capacitor
  • Low temperature

ASJC Scopus subject areas

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

Fields of Expertise

  • Advanced Materials Science

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