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Ab initio and kinetic Monte Carlo simulation study of lithiation in crystalline and amorphous silicon

机译:从头算和动力学蒙特卡洛模拟研究晶态和非晶态硅的锂化

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摘要

Energetics and kinetics of Li insertion into c-Si and a-Si systems are investigated using the density functional (DFT) theory calculations and kinetic Monte Carlo (KMC) simulations. DFT formation energies show the mechanism of phase separation between crystalline silicon and amorphous lithium silicide. Both crystalline and amorphous Si show similar trends in volume expansion and phase transition under lithiation, and kinetics of Li diffusion in bulk silicon (from DFT and KMC) shows a big difference between c-Si and a-Si. The Li migration barrier is 0.6 eV in c-Si, and quickly decreases to 0.4 eV under increasing Li concentration or Si volume expansion. To simulate Li diffusion in amorphous silicon using KMC, we have developed a formulation for environment dependent migration energy barriers of Li in a-Si using a volume dependent function. KMC simulations are performed for Li diffusion in both c-Si and a-Si, and the diffusion coefficient of Li in a-Si is an order of magnitude larger than in c-Si. These studies help to understand mechanisms of lithiation with atomic scale details and elucidate the phase separation between c-Si and lithium silicide.
机译:使用密度泛函(DFT)理论计算和动力学蒙特卡洛(KMC)模拟研究了Li插入c-Si和a-Si系统中的能量和动力学。 DFT形成能显示出晶体硅与非晶硅化锂之间的相分离机理。晶体硅和非晶硅在锂化下均显示出相似的体积膨胀和相变趋势,并且块状硅中的Li扩散动力学(来自DFT和KMC)在c-Si和a-Si之间显示出很大的差异。 Li迁移势垒在c-Si中为0.6 eV,在Li浓度增加或Si体积膨胀时迅速下降至0.4 eV。为了使用KMC模拟Li在非晶硅中的扩散,我们已经开发了一种使用体积依赖函数的锂在a-Si中与环境有关的迁移能垒的公式。针对c-Si和a-Si中的Li扩散进行了KMC模拟,并且Li在a-Si中的扩散系数比c-Si中的大一个数量级。这些研究有助于了解具有原子尺度细节的锂化机理,并阐明c-Si与硅化锂之间的相分离。

著录项

  • 来源
    《Journal of power sources》 |2014年第25期|1010-1017|共8页
  • 作者单位

    WCU Multiscale Mechanical Design Division, Department of Mechanical and Aerospace Engineering, Seoul National University, Seoul 151-742, Republic of Korea;

    Department of Mechanical Engineering, Kyung Hee University, Yongin 446-701, Republic of Korea;

    WCU Multiscale Mechanical Design Division, Department of Mechanical and Aerospace Engineering, Seoul National University, Seoul 151-742, Republic of Korea;

    WCU Multiscale Mechanical Design Division, Department of Mechanical and Aerospace Engineering, Seoul National University, Seoul 151-742, Republic of Korea, Department of Materials Science and Engineering and Department of Physics, The University of Texas at Dallas, Richardson, TX 75080, USA;

  • 收录信息 美国《科学引文索引》(SCI);美国《工程索引》(EI);美国《生物学医学文摘》(MEDLINE);
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

    Ab initio method; Kinetic Monte Carlo simulation; Silicon; Li diffusion; Phase separation;

    机译:从头算方法;动力学蒙特卡洛模拟;硅;锂扩散相分离;

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