乙腈对超级电容器内含水离子液体/石墨烯固液界面微观结构的影响  

Effect of Acetonitrile on the Interfacial Microstructure of Aqueous Ionic Liquids/Graphene in Supercapacitor

作　　者：宋粉红[1] 马佳明 王富康 范晶[1] SONG Fenhong;MA Jiaming;WANG Fukang;FAN Jing(School of Energy and Power Engineering,Northeast Electric Power University,Jilin 132012,China)

机构地区：[1]东北电力大学能源与动力工程学院,吉林132012

出　　处：《工程热物理学报》2024年第12期3671-3679,共9页Journal of Engineering Thermophysics

基　　金：国家自然科学基金资助项目(No.52206220);吉林省重点研发基金资助项目(No.20240304098SF)。

摘　　要：离子液体电解质在石墨烯表面的润湿特性对石墨烯离子液体超级电容器的储能性能至关重要。由于离子液体具有吸湿性在制备及应用过程中极易吸收水分,水的存在影响固液界面的离子分布及离子液体在石墨烯表面的润湿特性。有机溶剂乙腈有望减小离子液体的黏度且减少水的存在对电容性能的影响。本文通过分子动力学模拟研究了乙腈对含水离子液体在石墨烯电极壁面上的润湿性能的影响机理。结果表明,随着乙腈含量增加,即nH_(2)O:nACN从1:1变化到1:8时,亲水性和疏水性含水离子液体液滴在石墨烯表面的润湿性均显著增强,对应的接触角分别减少了42.46°、24.30°,亲水性离子液体体系润湿性增强效果更为显著。通过分析各离子、分子一维二维密度和离子/分子间径向分布函数,发现乙腈分子分布在近壁面层,且乙腈的加入改变了阴阳离子、水分子在固液界面的分布和相互作用,形成部分脱溶结构,有利于提高储能性能。此外,乙腈的存在使离子的扩散速率增加,阴阳离子、水、乙腈、固壁相互作用改变了含水离子液体液滴在石墨烯表面的润湿性。研究结果从微观角度深入探究了离子液体/石墨烯固液界面的微观结构,为开发和设计高性能石墨烯离子液体超级电容器提供了重要参考。The wetting properties of ionic liquid electrolytes on the graphene surface are crucial for the energy storage performance of graphene/ionic liquids supercapacitors.Due to the hygroabsorp-tion of ionic liquids,it inevitably absorbs water during the process of preparation and application,and the existence of water affects the distribution of ions at the solid-liquid interface and the wetting properties of ionic liquids on the graphene surface.The organic solvent acetonitrile is anticipated to decrease the viscosity of ionic liquids and mitigate the impact of water on the capacitive properties.In this paper,the microscopic mechanism of acetonitrile on the wetting characteristics of ionic liquids on the graphene surface.The results revealed that as the acetonitrile content increased,specifically when the ratio of nH_(2)O to nAcN varies from 1:1 to 1:8,the wettability of both hydrophilic and hydropho-bic aqueous ionic liquid droplets on the graphene surface was notably improved,the corresponding contact angles decreased by 42.46°and 24.30°respectively.And the wettability enhancement was more pronounced in the hydrophilic ionic liquids system.Through analysis of the one-dimensional and two-dimensional density profiles of each ion and molecule,as well as the radial distribution func-tion between ions/molecules,it was observed that acetonitrile molecules are distributed near the wall layer,and the addition of acetonitrile changes the distribution and interaction of cations,an-ions and water molecules at the solid-liquid interface,forming a partial desolvation structure,which is conducive to improving the energy storage performance.Moreover,the existence of acetonitrile increases the diffusion rate of ions,and the interactions among cations,anions,water,acetonitrile,and solid wall effect the wettability of aqueous ionic liquids droplets on the graphene surface.The results deeply explore the interfacial microstructure of ionic liquids droplet on graphene,and provide an important guidance for the development and design o

关 键 词：润湿 含水离子液体 固液界面 分子模拟 超级电容器 

分 类 号：TK121[动力工程及工程热物理—工程热物理]