Factors influencing the conductivity of crystalline polymer electrolytes

E Staunton, Yuri Georgievich Andreev, Peter Bruce, FRS

Research output: Contribution to journalArticlepeer-review

60 Citations (Scopus)

Abstract

Crystalline polymer electrolytes conduct, in contrast to the established view for 30 years. The crystalline polymer poly(ethylene oxide)(6): LiXF6, X = P, As, Sb is composed of tunnels formed from pairs of (CH2-CH2-O) n chains, within which the Li+ ions reside and along which they may migrate. The anions are located outside the tunnels. PEO6:LiXF6 formed from PEO of average molecular weight 1000 Da has an average chain length of 40 A compared with a typical crystallite size of 2500 A, hence low molecular weight materials have many chain ends within a crystallite. More chain ends increase conductivity. Materials composed of polydispersed PEO (chains of different lengths) of average molecular weight 1000 Da exhibit a conductivity one order of magnitude greater than monodispersed materials of the same molecular weight. Replacing the -OCH3 groups on the chain ends with -OC2H5 increases the conductivity by a further order of magnitude. Conductivity may also be increased by isovalent or aliovalent doping of the 6 : 1 complexes in which XF6- is replaced by N(SO2CF3)(2)(-) or SiF2-, respectively.

Original languageEnglish
Pages (from-to)143-156
Number of pages14
JournalFaraday Discussions
Volume134
DOIs
Publication statusPublished - 2007

Keywords

  • MOLECULAR-DYNAMICS SIMULATION
  • POWDER-DIFFRACTION DATA
  • IONIC-CONDUCTIVITY
  • PEO6-LIXF6
  • TRANSPORT
  • COMPLEXES
  • SB

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