Highly mobile segments in crystalline poly(ethylene oxide)8:NaPF6 electrolytes studied by solid-state NMR spectroscopy.
Highly mobile segments in crystalline poly(ethylene oxide)8:NaPF6 electrolytes studied by solid-state NMR spectroscopy.
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DOI：
10.1063/1.4865109
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发表时间：
2014-02
期刊：
影响因子：
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通讯作者：
Huan Luo;Xinmiao Liang;Liying Wang;Anmin Zheng;Chaoyang Liu;Jiwen Feng
中科院分区：
文献类型：
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作者：
Huan Luo;Xinmiao Liang;Liying Wang;Anmin Zheng;Chaoyang Liu;Jiwen Feng
制备了环氧乙烷(EO)/Na摩尔比为8:1和6:1的两种高结晶度聚环氧乙烷/NaPF6电解质，分别为PEO8:NaPF6和PEO6:NaPF6，Mw=6000 g mol(-1)，并对它们的离子电导率、结构和链段运动进行了研究和比较。 PEO8:NaPF6聚合物电解质的室温离子电导率为7.7×10(-7)S cm(-1)，约为PEO6:NaPF6的5倍。通过静态粉末光谱的变温测量和旋转坐标系中的 (1)H 自旋晶格弛豫时间 ((1)H T1ρ)，我们证明，与离子电导率较低的 PEO6:NaPF6 相比，离子电导率较高的结晶 PEO8:NaPF6 中的结晶链段具有更高的移动性。 PEO8:NaPF6 中聚合物链段的大角度重新取向运动在较低温度 (~233 K) 下开始，活化能为 0.31 eV，与纯 PEO 晶体相当。而 PEO6:NaPF6 中聚合物链段的大角度重新取向运动在 313 K 左右开始，活化能为 0.91 eV。由于温度增强的大角度重新取向，(13)C 静态粉末线形与具有化学位移 δ33 δ22 (δ11) 明显主值的低温宽图案发生显着变化。这表明结晶 PEO-盐复合物中的链段运动促进了离子电导率。
Two types of high-crystallinity poly(ethylene oxide)/NaPF6 electrolytes with ethylene oxide (EO)/Na molar ratios of 8:1 and 6:1, termed as PEO8:NaPF6 and PEO6:NaPF6 with Mw = 6000 g mol(-1) were prepared, and their ionic conductivity, structure, and segmental motions were investigated and compared. PEO8:NaPF6 polymer electrolyte exhibits the room-temperature ionic conductivity 7.7 × 10(-7) S cm(-1) which is about five times higher than the PEO6:NaPF6. By variable-temperature measurements of static powder spectra and (1)H spin-lattice relaxation time in rotation frame ((1)H T1ρ), we demonstrate that crystalline segments are more highly mobile in the crystalline PEO8:NaPF6 with higher ionic conductivity than in the PEO6:NaPF6 with lower ionic conductivity. The large-angle reorientation motion of polymer segments in the PEO8:NaPF6 onsets at lower temperature (∼233 K) with a low activation energy 0.31 eV that is comparable with that of the pure PEO crystal. Whereas, the large-angle reorientation motion of polymer segments in the PEO6:NaPF6 starts around 313 K with a high activation energy of 0.91 eV. As a result of the temperature-enhanced large-angle reorientations, the (13)C static powder lineshape changes markedly from a low-temperature wide pattern with apparent principal values of chemical shift δ33 δ22 (δ11). It is suggested that the segmental motion in crystalline PEO-salt complex promotes ionic conductivity.