Does decreasing ion-ion association improve cation mobility in single ion conductors?

Kan Ju Lin, Janna K. Maranas

Research output: Contribution to journalArticle

18 Scopus citations

Abstract

We report on poly(ethylene oxide) based single ion conductors for solid polymer electrolytes. The widely agreed upon vehicle for cation movement in PEO-based solid polymer electrolytes is the single cation, in which the cation is solvated by PEO ether oxygens. Here we report a different vehicle that becomes active with strong anion-cation interactions. In the common perspective, increasing ion-ion interactions would increase ion association, decrease cation solvation, and disable cation movement. Decreasing these interactions would have the opposite effect. We vary cation-anion interaction strength, using anion charge delocalization in molecular dynamics simulations. This creates a series of systems with levels of ion aggregation from single cations (weak interaction) to mostly ion aggregates (strong interaction). Although in the weak model single cations are faster than those in ion pairs and aggregates, with stronger interactions a different mechanism emerges. Paired cations move the fastest by visiting different anion partners in succession. The importance of this observation lies in the possibility of decoupling cation movement from polymer motion, which is required to prevent dendrite formation in both Li and Na ion batteries.

Original languageEnglish (US)
Pages (from-to)16143-16151
Number of pages9
JournalPhysical Chemistry Chemical Physics
Volume15
Issue number38
DOIs
StatePublished - Oct 14 2013

All Science Journal Classification (ASJC) codes

  • Physics and Astronomy(all)
  • Physical and Theoretical Chemistry

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