Rational design of viologen redox additives for high-performance supercapacitors with organic electrolytes  

合理设计紫精氧化/还原添加剂分子以构建高性能有机系超级电容器

作　　者：Yue Niu Jin Niu Yingjie Ma Linjie Zhi 牛越;牛津;马英杰;智林杰(CAS Key Laboratory of Nanosystem and Hierarchical Fabrication,CAS Center for Excellence in Nanoscience,National Center for Nanoscience and Technology,Beijing,100190,China;University of Chinese Academy of Sciences,Beijing,100039,China;Key Laboratory of Chemical Resource Engineering,Laboratory of Electrochemical Process and Technology for materials,Beijing University of Chemical Technology,Beijing,100029,China)

机构地区：[1]CAS Key Laboratory of Nanosystem and Hierarchical Fabrication,CAS Center for Excellence in Nanoscience,National Center for Nanoscience and Technology,Beijing,100190,China [2]University of Chinese Academy of Sciences,Beijing,100039,China [3]Key Laboratory of Chemical Resource Engineering,Laboratory of Electrochemical Process and Technology for materials,Beijing University of Chemical Technology,Beijing,100029,China

出　　处：《Science China Materials》2021年第2期329-338,共10页中国科学（材料科学（英文版）

基　　金：funding support from the Ministry of Science and Technology of China(2012CB933403);Beijing Natural Science Foundation(2182086);the National Natural Science Foundation of China(51425302 and 51302045)。

摘　　要：Introducing redox species into the electrolytes of traditional electric double layer capacitors(EDLCs)is an efficient strategy to enhance their energy density owing to Faradic reactions.However,few studies have elucidated the effect of the molecular structures of organic redox species on the performance of relative supercapacitors,which is important in the development of redox additives for super-capacitors.In this context,we synthesized several viologens and used them as new organic redox additives for super-capacitors with organic electrolytes.The detailed experimental analysis and theoretical calculation results show that the electrochemical performance of viologens relies heavily on their side chains and conjugated cores.Specifically,the side chains of the viologens affect their electronic structures and are consistent with behaviours between the molecules and the electrode pores due to the size effect,thus influencing their specific capacities.In addition,a larger conjugated aromatic core endows viologens with a smaller band gap and a higher degree of electron delocalization,resulting in better rate performance and cycling stability.Consequently,aπ-conjugated viologen derivative is selected as a favourable additive and enables an EDLC-type supercapacitor to exhibit a high energy density(34.0 W h kg^−1 at 856 W kg^−1)and good cycling performance.向双电层电容器的电解液中加入氧化还原活性添加剂是一种提升其能量密度的有效策略.添加剂的分子结构与其电化学性能密切相关,但目前添加剂"分子结构-电化学性能"的关系还不明确.因此,我们制备了一类适用于有机电解液的紫精基氧化还原添加剂,并研究了分子结构对其电化学行为的影响.研究发现,紫精分子的电化学性能与其侧链和共轭骨架密切相关:侧链影响其电子结构及其与电极孔道之间的匹配,进而影响其可逆容量;而更大的共轭骨架可以赋予紫精分子更小的带隙和更大的电子离域体系,从而提高其倍率性能和循环稳定性.结构优化的紫精分子添加剂可以使双电层电容器获得34.0 Wh kg^-1的高能量密度和优异的循环性能.

关 键 词：organic-soluble viologens redox additives molecular design organic electrolytes SUPERCAPACITORS 

分 类 号：O622[理学—有机化学] TM53[理学—化学]