MoS2薄膜负极材料的制备及其电化学行为

Synthesis and electrochemical performance of MoS2 thin film anode material

采用射频磁控溅射技术,以MoS2为溅射靶材,在不同溅射功率下制备了系列MoS2薄膜。利用X射线衍射仪(XRD)、扫描电镜(SEM)、透射电镜(TEM)和X射线光电子能谱(XPS)等测试手段对薄膜进行表征,探讨循环过程中薄膜结构与形貌变化及其对电池循环性能的影响。结果表明,所制备的薄膜为富S的MoS2非晶态薄膜;SEM分析表明薄膜中S与Mo元素分布均匀,不存在偏聚现象;XPS分析表明所制备的薄膜中存在单质S相,单质S相在整体薄膜中含量大体占14%(原子分数)左右。在初始充放电循环过程中,这些均匀分布的单质S和Li^+反应生成多硫化锂,产生不可逆损耗,从而原位形成分布均匀的多孔结构,可有效缓解薄膜后续循环过程中的体膨胀,同时增加活性材料比表面积,有利于改善薄膜比容量及循环稳定性。当靶功率为100 W时,薄膜电极循环20圈,放电比容量为429.8 mAh/g,经300圈循环,放电比容量仍可保持在420.4 mAh/g,表现出优异的循环稳定性。

MoS2 thin films were fabricated using RF magnetron sputtering method with MoS2 as sputtering targets at different sputtering powers.XRD,SEM,TEM and XPS were used to analyze the thin films.The change of film structure and morphology during cycling and its effect on the cycling performance of the electrodes were discussed.The results show that the prepared MoS2 thin films with S-rich content were amorphous.The SEM results show that the S and Mo elements in the film were uniformly distributed and there was no segregation phenomenon.The XPS analysis results show that the sulfur phase existed in the prepared film,and the content of sulfur phase in the overall film was about 14 at.%.During the initial cycling process,uniformly distributed porous structure was formed in situ by the irreversible loss of sulfur contained in the MoS2 film.The porous structure could effectively alleviate the volume expansion of the film during subsequent cycling process,and increase the specific surface area of the active material.When the target power was 100W,the discharge specific capacity of the film was 429.8 mAh/g after 20 cycles.And after 300 cycles,the discharge specific capacity still maintained at 420.4 mAh/g,exhibiting the excellent cycle stability.