Insight into the Electrical Double Layer of Ionic Liquids Revealed through Its Temporal Evolution
Insight into the Electrical Double Layer of Ionic Liquids Revealed through Its Temporal Evolution
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DOI：
10.1002/admi.202001313
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发表时间：
2020-11-04
影响因子：
5.4
通讯作者：
Espinosa-Marzal, Rosa M.
中科院分区：
文献类型：
--
作者：
Han, Mengwei;Kim, Hojun;Espinosa-Marzal, Rosa M.
离子液体(ILS)被认为是双电层电容器中潜在的理想电解液。然而，最近对离子液体中远程静电屏蔽的发现表明，这种对高浓度溶液中电双电层的理解仍然不完整。通过对广角X射线散射和表面力的精确随时间变化的测量，提供了对其电双层的新的分子洞察力。观察到了三种咪唑离子液体的纳米结构的超低演化，这反映了离子在受限和非受限(体相)状态下的重组。观察到的大块相变包括至少20h的ILS有序化，反映在离子之间的间距的扩张或收缩，这些离子排列在大约10 nm的区域中。这种转换证明了在力测量中测量的双电层的演化是合理的。ILS之间的细微差别源于静电和非静电相互作用之间的复杂平衡。这项工作揭示了离子液体结构演化的新的时间尺度，并为理解离子液体中的电双层提供了一个新的视角，对能量存储、润滑以及微纳电子器件等不同领域的研究具有重要意义。
Ionic liquids (ILs) are proposed as potentially ideal electrolytes for use in electrical double layer capacitors. However, recent discoveries of long-range electrostatic screening in ILs have revealed that this understanding of the electrical double layer in highly concentrated solutions is still incomplete. Through precise time-dependent measurements of wide-angle X-ray scattering and surface forces, novel molecular insight into their electrical double layer is provided. An ultraslow evolution of the nanostructure of three imidazolium ILs is observed, which reflects the reorganization of the ions in confined and unconfined (bulk) states. The observed phase transformation in the bulk consists of the ILs ordering over at least 20 h, reflected in an expansion or contraction of the spacing between the ions organized in domains of approximate to 10 nm. This transformation justifies the evolution of the electrical double layer measured in force measurements. Subtle differences between the ILs arise from the intricate balance between electrostatic and non-electrostatic interactions. This work reveals a new time scale of the evolution of the IL structure and offers a new perspective for understanding the electrical double layer in ILs, with implications on diverse areas of inquiry, such as energy storage, lubrication, as well as micro- and nanoelectronics devices.