File(s) under permanent embargo

Surprising effect of nanoparticle inclusion on ion conductivity in a lithium doped organic ionic plastic crystal

journal contribution
posted on 01.01.2009, 00:00 authored by Y Shekibi, S Pas, N Rocher, B Clare, A Hill, D MacFarlane, Maria ForsythMaria Forsyth
Doping lithium bis(trifluoromethanesulfonyl)amide (Li[NTf2]) into the N-ethyl,N′-methylpyrrolidinium bis(trifluoromethanesulfonyl)amide ([C2mpyr][NTf2]) plastic crystal material has previously indicated order of magnitude enhancements in ion transport and conductivity over pure [C2mpyr][NTf2]. Recently, conductivity enhancements in this ionic plastic crystal induced by SiO2 nanoparticles have also been reported. In this work the inclusion of SiO2 nanoparticles in Li ion doped [C2mpyr][NTf2] has been investigated over a wide temperature range by differential scanning calorimetry (DSC), impedance spectroscopy, positron annihilation lifetime spectroscopy (PALS), Raman spectroscopy, NMR spectroscopy and scanning electron microscopy (SEM). Solid state 1H NMR indicates that the addition of the nanoparticles increases the mobility of the [C2mpyr] cation and positron lifetime spectroscopy (PALS) measurements indicate an increase in mean defect size and defect concentration as a result of nanoparticle inclusion, especially with 10 wt% SiO2. Thus, the substantial drop in ion conductivity observed for this doped nanocomposite material was surprising. This decrease is most likely due to the decrease in mobility of the [NTf2] anion, possibly by its adsorption at the SiO2/grain boundary interface and concomitant decrease in mobility of the Li ion.

History

Journal

Journal of materials chemistry

Volume

19

Issue

11

Pagination

1635 - 1645

Publisher

Royal Society of Chemistry

Location

Cambridge, England

ISSN

0959-9428

eISSN

1364-5501

Language

eng

Publication classification

C1.1 Refereed article in a scholarly journal

Copyright notice

2009, Royal Society of Chemistry