Mechanism of Polysulfone-Based Anion Exchange Membranes Degradation in Vanadium Flow Battery.
The stability of hydrocarbon ion exchange membranes is one of the critical issues for a flow battery. However, the degradation mechanism of ion exchange membranes has been rarely investigated especially for anion exchange membranes. Here, the degradation mechanism of polysulfone based anion exchange membranes, carrying pyridine ion exchange groups, under vanadium flow battery (VFB) medium was investigated in detail. We find that sp(2) hybrid orbital interactions between pyridinic-nitrogen in 4,4'-bipyridine and benzylic carbon disrupt the charge state balance of pristine chloromethylated polysulfone. This difference in electronegativity inversely induces an electrophilic carbon center in the benzene ring, which can be attacked by the lone pair electron on the vanadium(V) oxygen species, further leading to the degradation of polymer backbone, while leaving the 4,4'-bipyridine ion exchange groups stable. This work represents a step toward design and construction of alternative type of chemically stable hydrocarbon ion exchange membranes for VFB.
Division of Energy Storage, Dalian Institute of Chemical Physics, Chinese Academy of Sciences , 457 Zhongshan Road, Dalian 116023, P. R. China.|Graduate School of Chinese Academy of Sciences , Beijing 100039, P. R. China.
Zhizhang
Z
Yuan
Division of Energy Storage, Dalian Institute of Chemical Physics, Chinese Academy of Sciences , 457 Zhongshan Road, Dalian 116023, P. R. China.|Collaborative Innovation Center of Chemistry for Energy Materials (iChEM) , Dalian 116023, P. R. China.
Xianfeng
X
Li
Division of Energy Storage, Dalian Institute of Chemical Physics, Chinese Academy of Sciences , 457 Zhongshan Road, Dalian 116023, P. R. China.|Graduate School of Chinese Academy of Sciences , Beijing 100039, P. R. China.
Yuyue
Y
Zhao
Division of Energy Storage, Dalian Institute of Chemical Physics, Chinese Academy of Sciences , 457 Zhongshan Road, Dalian 116023, P. R. China.|Collaborative Innovation Center of Chemistry for Energy Materials (iChEM) , Dalian 116023, P. R. China.
Huamin
H
Zhang
4,4′-bipyridine; anion exchange membranes; degradation mechanism; hybrid orbital; polysulfone; vanadium flow battery