Enhancing Cation Diffusion and Suppressing Anion Diffusion via Lewis-Acidic Polymer Electrolytes

Brett M. Savoie, Michael A. Webb, Thomas F. Miller

Research output: Contribution to journalArticle

39 Scopus citations

Abstract

Solid polymer electrolytes (SPEs) have the potential to increase both the energy density and stability of lithium-based batteries, but low Li+ conductivity remains a barrier to technological viability. SPEs are designed to maximize Li+ diffusivity relative to the anion while maintaining sufficient salt solubility. It is thus remarkable that poly(ethylene oxide) (PEO), the most widely used SPE, exhibits Li+ diffusivity that is an order of magnitude smaller than that of typical counterions at moderate salt concentrations. We show that Lewis-basic polymers like PEO favor slow cation and rapid anion diffusion, while this relationship can be reversed in Lewis-acidic polymers. Using molecular dynamics, polyboranes are identified that achieve up to 10-fold increases in Li+ diffusivities and significant decreases in anion diffusivities, relative to PEO in the dilute-ion regime. These results illustrate a general principle for increasing Li+ diffusivity and transference number with chemistries that exhibit weaker cation and stronger anion coordination.

Original languageEnglish (US)
Pages (from-to)641-646
Number of pages6
JournalJournal of Physical Chemistry Letters
Volume8
Issue number3
DOIs
StatePublished - Feb 2 2017
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Materials Science(all)
  • Physical and Theoretical Chemistry

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