TY - JOUR
T1 - Electrical conductivities and Li ion concentration-dependent diffusivities, in polyurethane polymers doped with lithium trifluoromethanesulfonimide (LiTFSI) or lithium perchlorate (LiClO4)
AU - Bandyopadhyay, S.
AU - Marzke, R. F.
AU - Singh, Rakesh
AU - Newman, Nathan
PY - 2010/12/20
Y1 - 2010/12/20
N2 - Electrical, thermal and Li transport properties have been measured for polyester polyol and isocyanate-based polyurethanes doped with lithium trifluoromethanesulfonimide (LiTFSI) and lithium perchlorate (LiClO 4). Electrical conductivities are estimated at 10-5- 10-6 S/cm near 300 K. The conductivities show a Vogel-Tammann-Fulcher (VTF) behavior over wide temperature ranges, characteristic of segmental polymer chain motions, and are approximately an order of magnitude larger for LiTFSI-doped than for perchlorate-doped samples. Differential scanning calorimetry (DSC) shows that Tg does not significantly depend on doping type or concentration. Room-temperature 7Li diffusivities, measured by pulsed gradient NMR, show an unexpected strong, linear increase with LiTFSI doping, but only a weak increase with LiClO4 content. These findings may indicate substantial Li clustering in the LiTFSI-doped polymers, but may also reflect the effects of doping upon interface conduction between hard and soft polymer domains. Charge carrier densities estimated from the Nernst-Einstein relation, using measured NMR diffusivity values and ionic conductivities, range from approximately 8% to 29% of total Li densities for LiTFSI, indicating that a significant fraction of Li is involved in room-temperature ionic conduction in this material. For LiCLO4 the carrier fraction is smaller, implying that Li is more tightly bound to its anion site.
AB - Electrical, thermal and Li transport properties have been measured for polyester polyol and isocyanate-based polyurethanes doped with lithium trifluoromethanesulfonimide (LiTFSI) and lithium perchlorate (LiClO 4). Electrical conductivities are estimated at 10-5- 10-6 S/cm near 300 K. The conductivities show a Vogel-Tammann-Fulcher (VTF) behavior over wide temperature ranges, characteristic of segmental polymer chain motions, and are approximately an order of magnitude larger for LiTFSI-doped than for perchlorate-doped samples. Differential scanning calorimetry (DSC) shows that Tg does not significantly depend on doping type or concentration. Room-temperature 7Li diffusivities, measured by pulsed gradient NMR, show an unexpected strong, linear increase with LiTFSI doping, but only a weak increase with LiClO4 content. These findings may indicate substantial Li clustering in the LiTFSI-doped polymers, but may also reflect the effects of doping upon interface conduction between hard and soft polymer domains. Charge carrier densities estimated from the Nernst-Einstein relation, using measured NMR diffusivity values and ionic conductivities, range from approximately 8% to 29% of total Li densities for LiTFSI, indicating that a significant fraction of Li is involved in room-temperature ionic conduction in this material. For LiCLO4 the carrier fraction is smaller, implying that Li is more tightly bound to its anion site.
KW - Impedance spectroscopy
KW - Ionic conduction
KW - Polyurethane
KW - VTF
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U2 - 10.1016/j.ssi.2010.09.057
DO - 10.1016/j.ssi.2010.09.057
M3 - Article
AN - SCOPUS:78649737497
SN - 0167-2738
VL - 181
SP - 1727
EP - 1731
JO - Solid State Ionics
JF - Solid State Ionics
IS - 39-40
ER -