Journal article
Ion conductive electrolyte membranes based on co-continuous polymer blends
Solid electrolyte membranes based on comb-shaped poly(ethylene glycol) (PEG) doped with lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) salt in blends with poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) have been studied. Membranes containing between 70 and 100 wt% PEG were prepared by a convenient two-step process where films containing a mixture of mono- and dimethacrylate-terminated PEG macromonomers, PVDF-HFP, LiTFSI, and a photoactivator were cast from acetone solutions, followed by UV-initiated polymerization of the macromonomers.
Microscopy of the membranes revealed a phase separated morphology with a microporous PVDF-HFP network embedded in comb-shaped PEG. The membranes were thermally stable at temperatures below the melting point of PVDF-HFP at 140 °C. Dynamic mechanical analysis (DMA) in the tension mode showed that the mechanical properties of the membranes were greatly improved both by the addition of PVDF-HFP and of dimethacrylate-terminated PEG macromonomer.
For example, the storage modulus at 25 °C and 1 Hz showed a three-fold increase after increasing the percentage of dimethacrylate-terminated PEG from 0 to 10 wt% in the macromonomer mixture. A broad shoulder on tan δ as a function of temperature indicated the existence of a PVDF-HFP rich amorphous interphase.
At room temperature, the membranes containing more than 80 wt% PEG reached ionic conductivities exceeding 10−5 S cm−1.
Language: | English |
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Year: | 2003 |
Pages: | 2168-2176 |
ISSN: | 13645501 and 09599428 |
Types: | Journal article |
DOI: | 10.1039/b304462a |