A superionic state in nano-porous double-layer capacitors: insights from Monte Carlo simulations

S. Kondrat, N. Georgi, M. V. Fedorov, A. A. Kornyshev

Research output: Contribution to journalArticle

178 Citations (Scopus)

Abstract

Recently observed anomalous properties of ionic-liquid-based nanoporous supercapacitors [C. Largot et al., J. Am. Chem. Soc., 2008, 130, 2730-2731] have attracted much attention. Here we present Monte Carlo simulations of a model ionic liquid in slit-like metallic nanopores. We show that exponential screening of the electrostatic interactions of ions inside a pore, as well as the image-charge attraction of ions to the pore surface, lead to the 'anomalous' increase of the capacitance with decreasing the pore width. The simulation results are in good agreement with the experimental data. The capacitance as a function of voltage is almost constant for low voltages and vanishes above a certain threshold voltage. For very narrow pores, these two regions are separated by a peak. With increase of the pore size the peak turns into a bump and disappears for wide pores. This effect, related to a specific character of the voltage-induced filling of nanopores with counterions at high densities, is yet to be verified experimentally.

Original languageEnglish
Pages (from-to)11359-11366
Number of pages8
JournalPhysical Chemistry Chemical Physics
Volume13
Issue number23
Early online date13 May 2011
DOIs
Publication statusPublished - 2011

Keywords

  • electrical double layer
  • temperature ionic liquids
  • gold electrode interfaces
  • differential capacitance
  • nanoporous carbon
  • simple extension
  • glassy carbon
  • surface
  • supercapacitor
  • dynamics
  • TIC - Bionanotechnology

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