Effect of monomer structure on ionic conductivity in a systematic set of polyester electrolytes

Danielle M. Pesko, Yukyung Jung, Alexandra L. Hasan, Michael A. Webb, Geoffrey W. Coates, Thomas F. Miller, Nitash P. Balsara

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62 Scopus citations


Polymer electrolytes may enable the next generation of lithium ion batteries with improved energy density and safety. Predicting the performance of new ion-conducting polymers is difficult because ion transport depends on a variety of interconnected factors which are affected by monomer structure: Interactions between the polymer chains and the salt, extent of dissociation of the salt, and dynamics in the vicinity of ions. In an attempt to unravel these factors, we have conducted a systematic study of the dependence of monomer structure on ionic conductivity, σ, and glass transition temperature, Tg, using electrolytes composed of aliphatic polyesters and lithium bis(trifluoromethanesulfonyl) imide (LiTFSI) salt. The properties of these electrolytes were compared to those of poly(ethylene oxide) (PEO), a standard polymer electrolyte for lithium batteries. We define a new measure of salt concentration, ρ, the number of lithium ions per unit length of the monomer backbone. This measure enables collapse of the dependence of both the σ and Tg on salt concentration for all polymers (polyesters and PEO). Analysis based on the Vogel-Tammann-Fulcher (VTF) equation reveals the effect of different oxygen atoms on ion transport. The VTF fits were used to factor out the effect of segmental motion in order to clarify the relationship between molecular structure and ionic conductivity. While the conductivity of the newly-developed polyesters was lower than that of PEO, our study provides new insight into the relationship between ion transport and monomer structure in polymer electrolytes.

Original languageEnglish (US)
Pages (from-to)118-124
Number of pages7
JournalSolid State Ionics
StatePublished - Jun 1 2016
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • General Chemistry
  • General Materials Science
  • Condensed Matter Physics


  • Ionic conductivity
  • Monomer structure
  • PEO
  • Polyester
  • Polymer electrolyte


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