Electrochemical characteristics and intercalation mechanism of ZnS/C composite as anode active material for lithium-ion batteries

ZnS/C composites were synthesized by a combined precipitation with carbon coating method. Morphology and structure of the as-prepared ZnS/C composite materials with carbon content of 4.6 wt%. 9.3 wt% and 11.4 wt% were characterized using TEM and XRD technique. TEM observation demonstrated that the ZnS/C (9.3 wt% C) composite showed excellent microstructure with 20-30 nm ZnS nanoparticles uniformly dispersed in conductive carbon network. Electrochemical tests showed that the ZnS/C (9.3 wt% C) composite presented superior performance with initial charge and discharge capacity of 1021.1 and 481.6 mAh/g at a high specific current of 400 mA/g, after 300 cycles, the discharge capacity of ZnS/C electrode still maintained at 304.4 mAh/g, with 63.2% of its initial capacity. The rate capability and low temperature performance of the ZnS/C (9.3 wt% C) composite were compared with commercial MCMB anode. The results showed that the ZnS/C (9.3 wt%) composite exhibited much better cycle capability and low temperature performance than MCMB anode. ZnS/C composite seems to be a promising anode active material for lithium ion batteries. Intercalation mechanism of the ZnS/C composites for lithium ion insertion-extraction is proposed based on the ex situ X-ray diffraction analysis incorporating with its electrochemical characteristics. (C) 2010 Elsevier Ltd. All rights reserved.