A series of polysulfone-based crosslinked anion exchange membranes (AEMs) with primary diaminebased crosslinkers has been prepared via simple a crosslinking process as low-cost and durable membranes for vanadium redox flow batteries (VRFBs). Chloromethylated polysulfone is used as a precursor polymer for crosslinked AEM5 (CAPSU-x) with different degrees of crosslinking. Among the deVeloped AEM5, CAPSU-2.5 shows outstanding dimensional stability and anion (Cl-, SO42-, and OH-) conductivity. Moreover, CAPSU-2.5 exhibits much lower vanadium ion permeability (2.72 x 10(-8) cm(2) min(-1)) than Nafion 115 (2.88 x 10(-6) cm(2) min(-1)), which results in an excellent coulombic efficiency of 100%. The chemical and operational stabilities of the membranes have been investigated via ex situ soaking tests in 0.1 M VO2+ solution and in situ operation tests for 100 cycles, respectively. The excellent chemical, physical, and electrochemical properties of the CAPSU-2.5 membrane make it suitable for use in VRFBs. (C) 2017 Elsevier B.V. All rights reserved.