Control of Ionic Mobility via Charge Size Asymmetry in Random Ionomers

Boran Ma, Trung Dac Nguyen, Monica Olvera De La Cruz*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

2 Scopus citations

Abstract

Solid polymer electrolytes are considered a promising alternative to traditional liquid electrolytes in energy storage applications because of their good mechanical properties, and excellent thermal and chemical stability. A gap, however, still exists in understanding ion transport mechanisms and improving ion transport in solid polymer electrolytes. Therefore, it is crucial to bridge composition-structure and structure-property relationships. Here, we demonstrate that size asymmetry, λ, represented by the ratio of counterion to charged monomer size, plays a key role both in the nanostructure and in the ionic dynamics. More specifically, when the nanostructure is modified by an external electric field such that the mobility cannot be described by linear response theory, two situations arise. The ionic mobility increases as λ decreases (small counterions) in the weak electrostatics (high dielectric constant) regime, whereas in systems with strong electrostatic interactions, ionomers with higher size symmetry (λ ≈ 1) display higher ionic mobility. Moreover, ion transport is found to be dominated by the hopping of the ions and not by moving ionic clusters (also known as "vehicular" charge transport). These results serve as a guide for designing ion-containing polymers for ion transport related applications.

Original languageEnglish (US)
Pages (from-to)43-49
Number of pages7
JournalNano letters
Volume20
Issue number1
DOIs
StatePublished - Jan 8 2020

Keywords

  • Size asymmetry
  • ionic dynamics
  • molecular dynamics simulation
  • random ionomers
  • solid polymer electrolytes

ASJC Scopus subject areas

  • Bioengineering
  • Chemistry(all)
  • Materials Science(all)
  • Condensed Matter Physics
  • Mechanical Engineering

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