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    张少阳, 刘宇, 刘洪来. 锂离子在石墨、MoS2及其复合材料中扩散过程的分子模拟及量子力学研究[J]. 华东理工大学学报(自然科学版), 2021, 47(2): 129-136. DOI: 10.14135/j.cnki.1006-3080.20191224004
    引用本文: 张少阳, 刘宇, 刘洪来. 锂离子在石墨、MoS2及其复合材料中扩散过程的分子模拟及量子力学研究[J]. 华东理工大学学报(自然科学版), 2021, 47(2): 129-136. DOI: 10.14135/j.cnki.1006-3080.20191224004
    ZHANG Shaoyang, LIU Yu, LIU Honglai. Molecular Simulation and Quantum Mechanical Study of Lithium Ion Diffusion in Graphite, MoS2 and Their Composites[J]. Journal of East China University of Science and Technology, 2021, 47(2): 129-136. DOI: 10.14135/j.cnki.1006-3080.20191224004
    Citation: ZHANG Shaoyang, LIU Yu, LIU Honglai. Molecular Simulation and Quantum Mechanical Study of Lithium Ion Diffusion in Graphite, MoS2 and Their Composites[J]. Journal of East China University of Science and Technology, 2021, 47(2): 129-136. DOI: 10.14135/j.cnki.1006-3080.20191224004

    锂离子在石墨、MoS2及其复合材料中扩散过程的分子模拟及量子力学研究

    Molecular Simulation and Quantum Mechanical Study of Lithium Ion Diffusion in Graphite, MoS2 and Their Composites

    • 摘要: 锂离子在电极材料中的传递性能对电池的充放电速率起着至关重要的作用。采用非平衡态分子动力学(NEMD)方法,模拟了充电过程中锂离子在石墨、MoS2及其复合材料(G/MoS2)中的迁移过程,考察了锂离子的非平衡态扩散时间、平衡态扩散系数(D)和吸附能,探究了石墨、MoS2层间距及边缘结构对锂离子扩散的影响。计算结果表明:锂离子的传递扩散系数与其自扩散系数间有5~7个数量级的差别;锂离子在石墨、MoS2中迁移的最佳层间距分别为0.42、0.75 nm;石墨边缘结构对锂离子迁移的促进效果依次为:C−OH>C−F>C= O>C−H。G/MoS2复合材料的分析结果表明:材料复合的均匀度越高,越有利于锂离子的扩散。

       

      Abstract: The transfer diffusion properties of lithium ions play an important role in the charge and discharge rate of lithium ion batteries (LIBs). In this article, we used non-equilibrium molecular dynamics (NEMD) simulation to mimic lithium ions migration behavior in graphite, MoS2 and their composites (G/MoS2 ) during charging process. Assisted by equilibrium molecular dynamics (EMD) simulation and quantum mechanics simulation, we investigated the relationship of the diffusion time, diffusion coefficient and adsorption energy of lithium ions, and examined the influences of layers spacing and edge structures of graphite and MoS2 on lithium ions diffusion. It was shown that transport diffusivity varied from the self-diffusivity by 5—7 orders of magnitudes, which indicated that the self-diffusion coefficient based on EMD could not properly describe the LIBs charging and discharging processes. The results also indicated that lithium ions had the highest diffusion rate when the layers spacing of graphite and MoS2 were 0.42 nm and 0.75 nm, respectively. The promoting effect of graphite edge structure on lithium diffusion was: C−OH > C−F > C= O > C−H. On the other hand, we compared the diffusion time of lithium ions when the edges of MoS2 were Mo atom and S atom, it was found that the difference between them was not significant. For G/MoS2 composites, we studied six kinds of composite structures, the analysis results showed that lithium ions had the fastest diffusion rate and the largest diffusion coefficient in the 1+1 composite structure. Therefore, the more homogeneous the composites are, the faster the diffusion will be.

       

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