Abstract
Polymer electrolytes based on poly(bis(methoxyethoxyethoxy)phosphazene) (MEEP) exhibit some of the highest room temperature ionic conductivities reported in a single-phase system. The mechanism of ionic transport in polymer electrolytes, particularly the nature of the charge-carrying species, has been poorly understood at the molecular level. Vibrational spectroscopy is used to determine the nature and relative amounts of ionic species present in MEEP-LiCF 3SO 3 as a function of salt concentration. The composition corresponding to the conductivity maximum is completely dominated by neutral cation - anion contact ion pairs and the triple anion species, {Li(CF 3SO 3) 2} -. Furthermore, the conductivity changes only slightly at higher salt concentrations where triple cations dominate. These data require a dissociation - reassociation mechanism of ion transport in which dynamic equilibrium is established between the various ionically associated species by exchange of individual Li + and CF 3SO 3 - ions. The individual ions migrate between associated ionic species through the liquidlike domains defined by the entangled ethylene oxide side chains.
Original language | English (US) |
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Pages (from-to) | 8699-8702 |
Number of pages | 4 |
Journal | Macromolecules |
Volume | 37 |
Issue number | 23 |
DOIs | |
State | Published - Nov 16 2004 |
All Science Journal Classification (ASJC) codes
- Organic Chemistry
- Polymers and Plastics
- Inorganic Chemistry
- Materials Chemistry