Li Hongbin, Fan Hao, Hu Bo, Hu Linlin, Chang Gang, Song Jiangxuan
State Key Laboratory for Mechanical Behavior of Materials, Shaanxi International Research Center for Soft Matter, Xi'an Jiaotong University, Xi'an, 710049, China.
Instrumental Analysis Center of, Xi'an Jiaotong University, Xi'an, 710049, China.
Angew Chem Int Ed Engl. 2021 Dec 20;60(52):26971-26977. doi: 10.1002/anie.202110010. Epub 2021 Nov 18.
A stable rod-like sulfonated viologen (R-Vi) derivative is developed through a spatial-structure-adjustment strategy for neutral aqueous organic redox flow batteries (AORFBs). The obtained R-Vi features four individual methyl groups on the 2,2',6,6'-positions of the 4,4'-bipyridine core ring. The tethered methyls confine the movement of the alkyl chain as well as the sulfonic anion, thus driving the spatial structure from sigmoid to rod shape. The R-Vi with weak charge attraction and large molecular dimension displays an ultralow membrane permeability that is only 14.7 % of that of typical sigmoid viologen. Moreover, the electron-donating effect of methyls endows R-Vi with the lowest redox potential of -0.55 V vs. SHE among one-electron-storage viologen-based AORFBs. The AORFB with the R-Vi anolyte and a K Fe(CN) catholyte exhibits an energy efficiency up to 87 % and extremely low capacity-fade rate of 0.007 % per cycle in 3200 continuous cycles.
通过空间结构调整策略，为中性水系有机氧化还原液流电池（AORFBs）开发了一种稳定的棒状磺化紫精（R-Vi）衍生物。所获得的R-Vi在4,4'-联吡啶核心环的2,2',6,6'-位上具有四个独立的甲基。连接的甲基限制了烷基链以及磺酸根阴离子的移动，从而促使空间结构从S形转变为棒状。具有弱电荷吸引力和大尺寸分子的R-Vi表现出超低的膜渗透率，仅为典型S形紫精的14.7%。此外，甲基的给电子效应赋予R-Vi在基于单电子存储紫精的AORFBs中相对于标准氢电极（SHE）最低的氧化还原电位-0.55 V。采用R-Vi阳极电解液和KFe(CN)阴极电解液的AORFB在3200次连续循环中表现出高达87%的能量效率和极低的容量衰减率，每循环仅为0.007%。
