A novel N115-g-PSBMA membrane containing zwitterionic groups was successfully prepared by grafting the zwitterionic SBMA (sulfobetaine methacrylate) onto Nafion 115 (N115) via SI-ATRP (surface-initiated atom transfer radical polymerization) technique. The N115-g-PSBMA membrane has shown higher hydrophilicity, lower vanadium permeability, higher coulombic efficiency and energy efficiency than that of commercial N115 membrane for VRB (vanadium redox flow battery) application. At the current density of 40-80 mA cm(-2), the average energy efficiency of the VRB with N115-g-PSBMA membrane has reached up to 87.3%, which is 2.6% higher than that of the VRB with N115 membrane at the same current densities. The method is expected to present a new direction to prepare novel separators with both excellent performances and low cost for VRB application.