石墨烯/硫复合正极材料的一步水热法制备与电化学性能

摘要

将硫代硫酸钠(Na2S2O3)与氧化石墨烯(GO)的混合溶液,在酸性条件下经过一步水热反应制备还原氧化石墨烯/硫(RGO/S)复合正极材料.实验探索了水热温度、反应时间、碳硫质量比例对材料的影响.通过X射线衍射(XRD)、扫描电镜(SEM)、透射电镜(TEM)和恒电流充放电对材料进行分析.结果表明在180°C下,碳硫质量比为3：7时,水热12 h得到的RGO/S复合材料具有优异的循环性能,首次放电比容量为931 mAh∙g-1,50次循环之后其比容量还保持在828.16 mAh∙g-1；RGO/S复合材料的充放电库仑效率在95%以上；同时RGO/S复合材料的倍率性能相比于单质硫有很大提高.一步水热法能够使硫分子均匀分布在石墨烯片层结构中,同时加强了石墨烯表面基团对硫分子的固定作用.%Reduced graphene oxide/sulfur (RGO/S) composites were synthesized by a one-step hydrothermal method using a mixture of sodium thiosulfate (Na2S2O3) and graphene oxide (GO) solution reacting under acid conditions. We explored the influence of the hydrothermal temperature, reaction time, and sulfur content on the composites. Analysis by X-ray diffraction (XRD), scanning electron microscope (SEM), and the galvanostatic charge and discharge shows that the composites have excellent cycling performance when synthesis occurs at 180 °C for 12 h to provide a carbon:sulfur mass ratio of 3:7. The first discharge capacity is delivered at 931 mAh∙g-1 and it remains at 828.16 mAh∙g-1 after 50 cycles. The coulomb efficiency of the composites is above 95%. In addition, the rate capability of these composites is much better than that of sulfur. Sulfur molecules can be evenly distributed between the graphene layers and fixed to the functional groups on the surface of graphene by this one-step hydrothermal method.