A facile in situ sulfur deposition route to obtain carbon-wrapped sulfur composite cathodes for lithium-sulfur batteries

An in situ sulfur deposition route has been developed for synthesizing sulfur-carbon composites as cathode materials for lithium-sulfur batteries. This facile synthesis method involves the precipitation of elemental sulfur at the interspaces between carbon nanoparticles in aqueous solution at room temperature. The product has been characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, charge-discharge measurements, and electrochemical impedance spectroscopy. The sulfur-carbon composite cathode with 75 wt.% active material thus obtained exhibits a remarkably high first discharge capacity of 1116 mAh g(-1) with good cycle performance, maintaining 777 mAh g(-1) after 50 cycles. The significantly improved electrochemical performance of the sulfur-carbon composite cathode is attributed to the carbon-wrapped sulfur network structure, which suppresses the loss of active material during charging/discharging and the migration of the polysulfide ions to the anode (i.e., shuttling effect). The integrity of the cathode structure during cycling is reflected in low impedance values observed after cycling. This facile in situ sulfur deposition route represents a low-cost approach to obtain high-performance sulfur-carbon composite cathodes for rechargeable Li-S batteries. (C) 2012 Elsevier Ltd. All rights reserved.