Singapore University of Technology and Design, 20 Dover Drive, Singapore 138682, Singapore.
Phys Chem Chem Phys. 2014 Mar 7;16(9):4260-7. doi: 10.1039/c3cp54320j.
By means of density functional theory, we systematically investigate the insertion and diffusion of Na and Li in layered Si materials (polysilane and H-passivated silicene), in comparison with bulk Si. It is found that Na binding and mobility can be significantly facilitated in layered Si structures. In contrast to the Si bulk, where Na insertion is energetically unfavorable, Na storage can be achieved in polysilane and silicene. The energy barrier for Na diffusion is reduced from 1.06 eV in the Si bulk to 0.41 eV in polysilane. The improvements in binding energetics and in the activation energy for Na diffusion are attributed to the large surface area and available free volume for the large Na cation. Based on these results, we suggest that polysilane may be a promising anode material for Na-ion and Li-ion batteries with high charge-discharge rates.
利用密度泛函理论，我们系统地研究了 Na 和 Li 在层状 Si 材料（聚硅烷和 H 钝化硅烯）中的插入和扩散，与体 Si 进行了比较。结果发现，Na 的结合和迁移可以在层状 Si 结构中得到显著促进。与 Si 体中 Na 的插入是不利的情况相反，Na 可以储存在聚硅烷和硅烯中。Na 扩散的能垒从 Si 体中的 1.06 eV 降低到聚硅烷中的 0.41 eV。Na 扩散的结合能和活化能的改善归因于大的 Na 阳离子的表面积大和可用的自由体积。基于这些结果，我们提出聚硅烷可能是一种很有前途的用于高倍率充放电的钠离子和锂离子电池的阳极材料。
