储能科学与技术 ›› 2023, Vol. 12 ›› Issue (3): 698-709.doi: 10.19799/j.cnki.2095-4239.2022.0669

• 储能材料与器件 • 上一篇    下一篇

MoS2/RGO复合材料的电化学性能和第一性原理研究

祝玉婷(), 闫共芹(), 林羽芊   

  1. 广西科技大学机械与汽车工程学院，广西 柳州 545616
  • 收稿日期:2022-11-11 修回日期:2022-12-09 出版日期:2023-03-05 发布日期:2022-12-29
  • 通讯作者: 闫共芹 E-mail:993847379@qq.com;ygq@gxust.edu.cn
  • 作者简介:祝玉婷（1996—），女，硕士研究生，主要研究方向为锂离子电池负极材料，E-mail： 993847379@qq.com；
  • 基金资助:
    广西自然科学基金项目(2020GXNSFAA159024);广西科技大学大学生创新创业训练计划项目(S202110594087)

Electrochemical properties and First-principles study of MoS2/rGO composite

Yuting ZHU(), Gongqin YAN(), Yuqian LIN   

  1. School of Mechanical and Automotive Engineering, Guangxi University of Science and Technology, Liuzhou 545616, Guangxi, China
  • Received:2022-11-11 Revised:2022-12-09 Online:2023-03-05 Published:2022-12-29
  • Contact: Gongqin YAN E-mail:993847379@qq.com;ygq@gxust.edu.cn

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摘要：

利用MoS2高的理论储锂容量和石墨烯良好的导电性能，采用一步水热法成功制备出卷曲片层状的MoS2/RGO复合材料，通过X射线衍射(XRD)、扫描电子显微镜(SEM)、X射线能谱(EDS)、Raman光谱等手段对其进行了结构、形貌、和成分的表征，并通过第一性原理计算了MoS2和MoS2/RGO模型的最稳定锂离子吸附位置、电荷密度、差分电荷密度、态密度和扩散能垒。实验结果表明，MoS2/RGO复合材料在前70次充放电循环中，保持着800 mAh/g以上的高放电比容量，经过100次循环后，放电比容量为515.3 mAh/g，明显高于单一MoS2(170.8 mAh/g)，同时，该复合材料具有优于单一MoS2的倍率性能，经过1000 mA/g的大电流密度循环后重新回到100 mA/g时，MoS2/RGO复合材料仍保持在高的放电比容量(941.2 mAh/g)。第一性原理计算结果表明，在石墨烯的作用下，MoS2层的Mo原子附近的电荷呈减少趋势，MoS2/RGO整体态密度增强，使价带中的电子更容易跃迁到导带，同时，MoS2/RGO较单一MoS2低的扩散能垒(0.25 eV)使锂离子更容易扩散，这解释了在石墨烯的作用下，MoS2/RGO复合材料拥有优于单一MoS2的电化学性能。

关键词: 水热法制备, MoS2/RGO复合材料, 电化学性能, 第一性原理计算

Abstract:

Based on the high theoretical lithium storage capacity of molybdenum disulfide (MoS2) and the good conductivity of graphene, a curly lamellar MoS2/reduced graphene oxide (RGO) composite was successfully prepared by a one-step hydrothermal method. The structure, morphology, and composition of the MoS2/RGO composite were characterized using an X-ray diffractometer, scanning electron microscope, X-ray energy spectrometer, and Raman spectrometer. The most stable adsorption position of lithium-ion, charge density, charge density difference, density of states, and diffusion energy barrier of MoS2 and MoS2/RGO models were calculated by first-principles. Results show that the MoS2/RGO composite maintains a high discharge specific capacity of more than 800 mAh/g in the first 70 charge and discharge cycles. After 100 cycles, the discharge specific capacity of the MoS2/RGO composite is 515.3 mAh/g, which is significantly higher than that of MoS2 (170.8 mAh/g). Simultaneously, the composite material shows a better rate of performance than MoS2. When the current density is back to 100 mA/g after the 1000 mA/g high current density cycle, the MoS2/RGO composite still maintains a high discharge specific capacity (941.2 mAh/g). The first-principles calculation results show that the charge near the Mo atom of MoS2 decreases, and the whole density of states of the MoS2/RGO composite is enhanced due to the action of graphene, making it easier for electrons in the valence band to migrate to the conduction band. Furthermore, compared with MoS2, the low diffusion energy barrier (0.25 eV) of MoS2/RGO makes it easier for lithium ions to diffuse. Therefore, it explains why the MoS2/RGO composite has a better electrochemical performance than MoS2 with the effect of graphene.

Key words: hydrothermal preparation, MoS2/RGO composite, electrochemical performance, first-principles calculation

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