Ion distribution in electrified micropores and its role in the anomalous enhancement of capacitance

Guang Feng, Rui Qiao, Jingsong Huang, Bobby G. Sumpter, Vincent Meunier

Research output: Contribution to journalArticlepeer-review

185 Scopus citations

Abstract

The distribution of K+ ions in electrified slit-shaped micropores with pore widths ranging from 9.36 to 14.7 Å was studied using molecular dynamics simulations. We show that, in slit pores with pore widths between 10 and 14.7 Å, the K+ ion distribution differs qualitatively from that described by classical electrical double-layer (EDL) theories in that fully hydrated K+ ions accumulate primarily in the central plane of the slit pores. This phenomenon disappears when the pore width is narrower than 10 Å. Ion hydration and water-water interactions, which are rarely considered in prior EDL theories for micropores, are found to be responsible for this behavior. On the basis of these results, we have developed a new sandwich capacitance model to describe the capacitance of the EDLs formed by K+ ions enclosed in slit-shaped micropores. This model is capable of predicting the anomalous enhancement of capacitance experimentally observed in micropores.

Original languageEnglish (US)
Pages (from-to)2382-2390
Number of pages9
JournalACS nano
Volume4
Issue number4
DOIs
StatePublished - Apr 27 2010

All Science Journal Classification (ASJC) codes

  • General Materials Science
  • General Engineering
  • General Physics and Astronomy

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