A novel core-shell structure carbon-sulfur composite with PEG and sulfonated groups grafted carbon core is synthesized via a feasible method in aqueous solution. The effect of carbon core grafting on the properties of the composite has been discussed. The XRD and SEM results reveal that sulfur is deposited on the surface of sulfonated and PEG grafted carbon core homogeneously. The ac impedance spectroscopy and charge/discharge tests show that the improved electrochemical properties of the composite are due to the grafting on the surface of carbon core. The cell, based on this core-shell structure composite with sulfur content of 82.5% as cathode material, exhibits excellent cycling performance with a reversible capacity about 800 mA h g(-1) after 100 cycles and good rate capability when the sulfur loading of the cathode is about 2.5 mg cm(-2). (C) 2015 The Electrochemical Society. All rights reserved.