摘要
Electric double layer capacitors(EDLCs),which store free charges on the electrode surface via non-Faradaic process,balanced by the electric double layer on the electrolyte side,exhibit excellent cycle stability and high power density.Though EDLCs are considered as promising energy storage devices,the charges stored on the electrode surface in EDLCs are much lower than those in batteries.Ionic liquids(ILs),as a new type of electrolytes in EDLCs,are capable to deliver high energy density,due to their excellent physicochemical properties and wide electrochemical window.In this review,we focus on the widely studied IL electrolytes for EDLCs,including pure ILs,IL/IL binary electrolytes,IL/organic solvent mixtures,as well as functionalized ILs,with attention on the relationship between the structures of different IL-based electrolytes and the energy storage properties in EDLCs.For imidazolium-and ammonium-based IL electrolytes which are most widely studied in EDLCs,the former generally have higher gravimetric specific capacitance,while the latter exhibit wider electrochemical window.The modifications of functional group substituted can be an effective strategy to enhance the gravimetric specific capacitance of the latter and thus improve the energy density of EDLCs.
双电层电容器(EDLCs)通过非法拉第过程在电极表面储存自由电荷,其通过电解质侧的双电层平衡,具有优异的循环稳定性和高功率密度.虽然EDLC被认为是有前景的能量储存器件,但其电极表面存储的电荷远低于电池,其较低的能量密度限制了其应用.离子液体(ILs),因其较宽的电化学窗口和独特的物理化学性能,可显著提高EDLCs的能量密度.本文综述了纯ILs、IL/IL二元混合体系、IL/有机溶剂混合体系以及功能化ILs等电解液,着重探讨了ILs的离子组成、尺寸、结构与电容的关系.咪唑类和季铵盐类ILs作为目前研究最广泛的两类ILs,前者一般具有较高的重量比电容,后者则表现出更宽的电化学窗口.故可对季铵盐类ILs进行官能化以提高其重量比电容,进而提高EDLCs的能量密度.
作者
Li Yin
Shu Li
Xiaohong Liu
Tianying Yan
尹莉;李姝;刘晓红;言天英(Institute of New Energy Chemistry, School of Materials Science and Engineering, National Institute for Advanced Materials, Nankai University)
基金
supported by the National Natural Science Foundation of China (21373118, 21573112, 21421001 and 21703108)
