Ion Conduction in Polymerized Ionic Liquids with Different Pendant Groups
Ion Conduction in Polymerized Ionic Liquids with Different Pendant Groups
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DOI：
10.1021/acs.macromol.5b00257
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发表时间：
2015-07-14
期刊：
影响因子：
5.5
通讯作者：
Sokolov, Alexei P.
中科院分区：
文献类型：
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作者：
Fan, Fei;Wang, Yangyang;Sokolov, Alexei P.
聚合离子液体（PolyIL）是能源存储和电化学设备应用的有希望的候选者。了解它们的离子传输机制是设计高导电性 PolyIL 的关键。通过使用宽带介电谱（BDS）、流变学和差示扫描量热法（DSC），进行了系统研究，以更好地了解具有不同侧基的PolyILs中的离子传输机制。侧基的变化导致这些 PolyIL 具有不同的介电、机械和热性能。瓦尔登图分析表明，所有这些 PolyIL 的数据点都落在理想瓦尔登线之上，并且在接近玻璃化转变温度 (T-g) 时，与理想线的偏差会增加。这些PolyIL在其T(g)下的电导率远高于通常报道的聚合物电解质的值（类似于聚合物电解质的10(-15) S/cm），其中离子传输与链段动力学紧密耦合。这些结果表明离子电导率与这些材料中的链段弛豫脱钩。解偶联程度随着聚合物链段松弛脆性的增加而增加。我们将这一观察结果与聚合物填充效率随脆性增加而降低联系起来。
Polymerized ionic liquids (PolyILs) are promising candidates for energy storage and electrochemical devices applications. Understanding their ionic transport mechanism is the key for designing highly conductive PolyILs. By using broadband dielectric spectroscopy (BDS), rheology, and differential scanning calorimetry (DSC), a systematic study has been carried out to provide a better understanding of the ionic transport mechanism in PolyILs with different pendant groups. The variation of pendant groups results in different dielectric, mechanical, and thermal properties of these PolyILs. The Walden plot analysis shows that the data points for all these PolyILs fall above the ideal Walden line, and the deviation from the ideal line increases upon approaching the glass transition temperature (T-g). The conductivity for these PolyILs at their T(g)s are much higher than the usually reported value similar to 10(-15) S/cm for polymer electrolytes, in which the ionic transport is closely coupled to the segmental dynamics. These results indicate a decoupling of ionic conductivity from the segmental relaxation in these materials. The degree of decoupling increases with the increase of the fragility of polymer segmental relaxation. We relate this observation to a decrease in polymer packing efficiency with an increase in fragility.