SnS_2-SnO_2/石墨烯复合材料的合成及其电化学储锂性能的研究

Synthesis and Electrochemical Li-storage Performance of SnS_2-SnO_2/Graphene Composites

目的制备高容量和循环性能稳定的锂离子电池复合电极材料。方法通过L-半胱氨酸(Lcys)辅助水热法合成SnS2-SnO2/石墨烯复合纳米材料,采用XRD,SEM,TEM和HRTEM技术对其进行结构表征,并采用循环伏安、恒流充放电和电化学阻抗技术研究了其电化学贮锂性能。结果随着水热溶液中L-cys的量增加,复合材料中少层数结构SnS2的含量也增加。当Sn4+/L-cys的物质的量之比为1∶4时,制得了SnS2/石墨烯复合纳米材料,而且石墨烯的存在在一定程度上抑制了SnS2沿c轴方向的生长,减少了层状SnS2的层数。结论由于二维层状结构的SnS2具有与石墨烯类似的微观结构和形貌,与石墨烯的复合具有更好的匹配性和相互协同效应,增强了SnS2/石墨烯复合材料的电化学贮锂性能,使其具有较高的可逆储锂容量、良好的循环性能和增强的倍率特性。

Objective To prepare the nanomaterials with high specific capacity and stable cyclic performance as Li-ion battery anode. Methods The SnO2-SnS2/GNS composites were prepared by an L-cys-assisted hydrothermal method and characterized by XRD, SEM, TEM and HRTEM. The electrochemical performances of the composites for reversible lithium storage were measured＆amp;nbsp;by cyclic voltammogram, galvanostatic charge/discharge and electrochemical impedance spectroscopy. Results With the increasing amount of L-cys in the hydrothermal solution, the content of SnS2 in the low-rise structure of the composite material also increased. The SnS2/graphene nanocomposite could be prepared when the molar ratio of Sn^4＋/L-cys was 1 ∶ 4. The presence of graphene in-hibited the growth of SnS2 along the c-axis direction to some extent, and reduced the layer number of the layered SnS2 . Conclusion Because the two-dimensional layered SnS2 had similar morphology and microstructure to graphene, the compositing of the layered SnS2 with graphene exhibited better synergetic effects. Therefore, the SnS2/graphene nanocomposite showed a high reversible spe-cific capacity with stable cyclic performance and enhanced rate capability.