Segmental Motion of PEO8∶NaPF6 Crystalline Polymer Electrolyte

doi:10.11938/cjmr20150102

Abstract

Abstract:

Solid-state NMR spectroscopy was used to study the segmental motion of high-crystallinity PEO8∶NaPF6 electrolytes with different PEO molecular weights (Mw =1 000 and 6 000 g/mol, respectively). ¹³C-magic angle spinning (MAS) NMR spectra and static powder patterns, as well as static 2D exchange spectra, revealed that large-angle reorientation of the crystalline PEO segments in both PEO8∶NaPF6 complexes starts at a very low temperature (~243 K), similar to the case in pure crystalline PEO. At higher temperature, long-range reorientation gives rise to a well-defined high-temperature powder pattern of uniaxial chemical shift anisotropy (δ₃₃ > δ₂₂ = δ₁₁), perhaps as the result of flipping of PEO. In contrast to other PEO/Na (Li) solid electrolytes, the segments in crystalline PEO8∶NaPF6 are highly mobile even when coordinated with Na+, and this is comparable with PEO. It is suggested that the segmental motion in crystalline PEO8∶NaPF6 electrolyte can enhance ion transportation along the coil, improving ionic conductivity.

Key words: solid-state NMR, polymer dynamics, ionic conductivity, PEO, PEO8∶NaPF6

CLC Number:

O482.53

LUO Huan1,2，LIANG Xin-miao1,2，FENG Ji-wen1，Wang Li-ying1. Segmental Motion of PEO8∶NaPF6 Crystalline Polymer Electrolyte[J]. Chinese Journal of Magnetic Resonance, 2015, 32(1): 12-22.

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