Preparation and performance of a core–shell carbon/sulfur material for lithium/sulfur battery

Abstract

The core–shell carbon/sulfur material with high performance is prepared by a facile and fast deposit method in an aqueous solution. As sulfur ratio is 85% (w/w) in the composite, scanning electron microscope (SEM) and transmission electron microscope (TEM) observation show that the moniliform particles with 10 nm sulfur shells preserve the morphology of carbon cores. Tested as the cathode material in a lithium cell with binary organic electrolyte at room temperature, the composite shows excellent electrochemical performance. It exhibits a specific capacity up to 1232.5 mAh g −1 at the initial discharge and its specific capacity remained above 800 mAh g −1 after 50 cycles. Meanwhile, the composite also exhibits the high-rate behavior at 800 mA g −1 of current density. Assuming a complete reaction to the final product, Li 2S, the utilization of the electrochemically active sulfur is about 85% at the initial cycle. Electrochemical impedance spectroscopy (EIS) is introduced to understand the impact of the microstructure of composite on electrochemistry. According to our study, a novel core–shell structural carbon/sulfur material is proposed and the key factors of the preparation are discussed.