中国物理B ›› 2021, Vol. 30 ›› Issue (10): 107102-107102.doi: 10.1088/1674-1056/ac0692

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Peculiar diffusion behavior of AlCl4 intercalated in graphite from nanosecond-long molecular dynamics simulations

Qianpeng Wang(王乾鹏)1, Daye Zheng(郑大也)1, Lixin He(何力新)1,†, and Xinguo Ren(任新国)2,‡   

  1. 1 CAS Key Laboratory of Quantum Information, University of Science and Technology of China, Hefei 230026, China;
    2 Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
  • 收稿日期:2021-04-24 修回日期:2021-05-27 接受日期:2021-05-29 出版日期:2021-09-17 发布日期:2021-10-08
  • 通讯作者: Lixin He, Xinguo Ren E-mail:helx@ustc.edu.cn;renxg@iphy.ac.cn
  • 基金资助:
    Project supported by the National Key Research and Development Program of China (Grant No. 2016YFB0201202) and the National Natural Science Foundation of China (Grant Nos. 11874335 and 11774327).

Peculiar diffusion behavior of AlCl4 intercalated in graphite from nanosecond-long molecular dynamics simulations

Qianpeng Wang(王乾鹏)1, Daye Zheng(郑大也)1, Lixin He(何力新)1,†, and Xinguo Ren(任新国)2,‡   

  1. 1 CAS Key Laboratory of Quantum Information, University of Science and Technology of China, Hefei 230026, China;
    2 Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
  • Received:2021-04-24 Revised:2021-05-27 Accepted:2021-05-29 Online:2021-09-17 Published:2021-10-08
  • Contact: Lixin He, Xinguo Ren E-mail:helx@ustc.edu.cn;renxg@iphy.ac.cn
  • Supported by:
    Project supported by the National Key Research and Development Program of China (Grant No. 2016YFB0201202) and the National Natural Science Foundation of China (Grant Nos. 11874335 and 11774327).

摘要: The diffusion property of the intercalated species in the graphite materials is at the heart of the rate performance of graphite-based metal-ion secondary battery. Here we study the diffusion process of a AlCl4 molecule within graphite – a key component of a recently reported aluminum ion battery with excellent performance – via molecular dynamics (MD) simulations. Both ab-initio MD (AIMD) and semiempirical tight-binding MD simulations show that the diffusion process of the intercalated AlCl4 molecule becomes rather inhomogeneous, when the simulation time exceeds approximately 100 picoseconds. Specifically, during its migration in between graphene layers, the intercalated AlCl4 molecule may become stagnant occasionally, and then recovers its normal (fast) diffusion behavior after halting for a while. When this phenomenon occurs, the linear relationship of the mean squared displacement (MSD) versus the duration time is not fulfilled. We interpret this peculiar behavior as a manifestation of inadequate sampling of rare event (the stagnation of the molecule), which does not yet appear in short-time MD simulations. We further check the influence of strains present in graphite intercalated compounds (GIC) on the diffusion properties of AlCl4, and find that their presence in general slows down the diffusion of the intercalated molecule, and is detrimental to the rate performance of the GIC-based battery.

关键词: diffusion, molecular dynamics calculations, graphite, electrodes

Abstract: The diffusion property of the intercalated species in the graphite materials is at the heart of the rate performance of graphite-based metal-ion secondary battery. Here we study the diffusion process of a AlCl4 molecule within graphite – a key component of a recently reported aluminum ion battery with excellent performance – via molecular dynamics (MD) simulations. Both ab-initio MD (AIMD) and semiempirical tight-binding MD simulations show that the diffusion process of the intercalated AlCl4 molecule becomes rather inhomogeneous, when the simulation time exceeds approximately 100 picoseconds. Specifically, during its migration in between graphene layers, the intercalated AlCl4 molecule may become stagnant occasionally, and then recovers its normal (fast) diffusion behavior after halting for a while. When this phenomenon occurs, the linear relationship of the mean squared displacement (MSD) versus the duration time is not fulfilled. We interpret this peculiar behavior as a manifestation of inadequate sampling of rare event (the stagnation of the molecule), which does not yet appear in short-time MD simulations. We further check the influence of strains present in graphite intercalated compounds (GIC) on the diffusion properties of AlCl4, and find that their presence in general slows down the diffusion of the intercalated molecule, and is detrimental to the rate performance of the GIC-based battery.

Key words: diffusion, molecular dynamics calculations, graphite, electrodes

中图分类号:  (Diffusion)

  • 82.56.Lz
71.15.Pd (Molecular dynamics calculations (Car-Parrinello) and other numerical simulations) 81.05.uf (Graphite) 82.45.Fk (Electrodes)