Ion Transport and Mechanical Properties of Non-Crystallizable Molecular Ionic Composite Electrolytes
Ion Transport and Mechanical Properties of Non-Crystallizable Molecular Ionic Composite Electrolytes
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非结晶分子离子复合电解质的离子输运和力学性能
DOI：
10.1021/acs.macromol.9b02125
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发表时间：
2020-02-25
期刊：
影响因子：
5.5
通讯作者：
Colby, Ralph H.
中科院分区：
文献类型：
--
作者：
Bostwick, Joshua E.;Zanelotti, Curt J.;Colby, Ralph H.
聚合物电解质显示出作为能量储存和转换装置中常规电解质的替代物的前景，但由于其离子电导率和模量之间的逆相关性而受到限制。在这项研究中，我们研究的表面形态，线性粘弹性，介电和扩散性能的分子离子复合材料（MIC），通过结合的刚性和带电的双螺旋聚合物，聚（2，2 '-二磺酰基-4，4'-联苯胺酰胺）（PBDT），和离子液体（IL）的材料。为了探测极端温度，我们加入了一个不可结晶的IL，以允许从-90至200摄氏度的测量。当我们增加PBDT重量百分比时，剪切模量增加并且在高达200 ° C时不衰减，同时将室温离子电导率保持在纯IL的2倍内。我们通过在很宽的温度范围内的Haven比连接IL离子的扩散系数与离子电导率，并分析离子传输的趋势的基础上相对较高的和组合物依赖的静态介电常数。这种行为可能是由于IL离子在这些网络中的集体重排。我们建议，这些属性是由一个两相系统中的MIC对应于IL丰富的“水坑”和PBDT-IL相关的“束”，其中IL离子形成交替鞘的阳离子和阴离子周围的每个PBDT棒。这些基于聚合物的MIC电解质显示出用于需要快速离子传输、高模量和宽热窗口的电化学装置的巨大前景。
Polymer electrolytes show promise as alternatives to conventional electrolytes in energy storage and conversion devices but have been limited due to their inverse correlation between ionic conductivity and modulus. In this study, we examine surface morphology, linear viscoelastic, dielectric and diffusive properties of molecular ionic composites (MICs), materials produced through the combination of a rigid and charged double helical polymer, poly(2,2'-disulfonyl-4,4'-benzidine terephthalamide) (PBDT), and ionic liquids (ILs). To probe temperature extremes, we incorporate a non-crystallizable IL to allow measurements from -90 to 200 degrees C. As we increase the PBDT weight percentage, shear moduli increase and do not decay up to 200 degrees C while maintaining room temperature ionic conductivity within a factor of 2 of the neat IL. We connect diffusion coefficients of IL ions with ionic conductivity through the Haven ratio across a wide temperature range and analyze trends in ion transport based on a relatively high and composition-dependent static dielectric constant. This behavior may result from collective rearrangement of IL ions in these networks. We propose that these properties are driven by a two-phase system in MICs corresponding to IL-rich "puddles" and PBDT-IL associated "bundles" where IL ions form alternating sheaths of cations and anions around each PBDT rod. These polymer-based MIC electrolytes show great promise for use in electrochemical devices that require fast ion transport, high modulus, and a broad thermal window.