Department of Chemical Engineering, Norwegian University of Science and Technology , 7491 Trondheim, Norway.
Department of Materials Science and Engineering and A. J. Drexel Nanomaterials Institute, Drexel University , Philadelphia, Pennsylvania 19104, United States.
J Am Chem Soc. 2017 Dec 27;139(51):18681-18687. doi: 10.1021/jacs.7b10693. Epub 2017 Dec 14.
Ion-ion interactions in supercapacitor (SC) electrolytes are considered to have significant influence over the charging process and therefore the overall performance of the SC system. Current strategies used to weaken ionic interactions can enhance the power of SCs, but consequently, the energy density will decrease due to the increased distance between adjacent electrolyte ions at the electrode surface. Herein, we report on the simultaneous enhancement of the power and energy densities of a SC using an ionic mixture electrolyte with different types of ionic interactions. Two types of cations with stronger ionic interactions can be packed in a denser arrangement in mesopores to increase the capacitance, whereas only cations with weaker ionic interactions are allowed to enter micropores without sacrificing the power density. This unique selective charging behavior in different confined porous structure was investigated by solid-state nuclear magnetic resonance experiments and further confirmed theoretically by both density functional theory and molecular dynamics simulations. Our results offer a distinct insight into pairing ionic mixture electrolytes with materials with confined porous characteristics and further propose that it is possible to control the charging process resulting in comprehensive enhancements in SC performance.
超级电容器 (SC) 电解液中的离子-离子相互作用被认为对充电过程有重大影响，从而影响整个 SC 系统的性能。目前用于削弱离子相互作用的策略可以提高 SC 的功率，但由于电极表面相邻电解质离子之间的距离增加，能量密度会降低。在此，我们报告了使用具有不同类型离子相互作用的离子混合物电解质同时提高 SC 的功率和能量密度。两种具有更强离子相互作用的阳离子可以在介孔中以更密集的方式排列以增加电容，而只有具有较弱离子相互作用的阳离子才能进入微孔而不牺牲功率密度。通过固态核磁共振实验研究了不同受限多孔结构中的这种独特的选择性充电行为，并通过密度泛函理论和分子动力学模拟进一步从理论上得到证实。我们的结果为将离子混合物电解质与具有受限多孔特性的材料进行配对提供了一个独特的视角，并进一步提出可以控制充电过程，从而全面提高 SC 的性能。
