Silicene -- A New Lithium Battery Negative Material

Lithium-ion batteries are the most commonly used energy storage devices. They are widely used in smartphones, laptops, and electric vehicles due to their portability, environmental friendliness, and high energy density. The most commonly used negative electrode material is graphite, and the van der Waals force between the layers ensures the stability of the material during charging and discharging and the recycling service life. However, due to the small lattice constant, which limits the position of lithium ions that can be interpolated, the capacity value is low. Finding a material with high capacity and cyclic stability is a hot topic in lithium-ion battery research.

Silicene is a layered Silicon material with a honeycomb structure and can be prepared by molecular beam Epitaxy and solid-phase reaction. Since in silylene, the bond length between Silicon atoms is much larger than the bond between carbon atoms in graphene, the arrangement of atoms between the silylene layers has a curved arrangement structure. Compared to the Silicon material of the traditional diamond structure, the interlayer coupling of silicene is Van der Waals force, and the space between the layer and the layer provides a space for lithium ion insertion, ensuring that the structure of the silicene is not destroyed during the charging and discharging process. In order to avoid the traditional Silicon electrode material in the process of charge and discharge electrode volume expansion problem. The stability and cycle times of negative electrode materials made of silicene can be greatly improved. Compared with graphite, multi-layer silicene has a larger lattice constant, and its theoretical capacity can reach about three times that of graphite.

Recently, the Du Yi team of Woolungong University in Australia prepared monolay/multilayer silicene samples by molecular beam Epitaxy, and studied the atomic and electronic structure of silicene in detail with a scanning tunneling microscope. The results of the study clearly show that the ABA of silene? Structure. The dirac fermion characteristics of silicene were determined by angular resolution photoelectron spectrometer. This study shows that the electrons in silicene have extremely fast transmission speed and solve the problem of poor conductivity in traditional Silicon materials. In addition, the study also showed that the stability of silicene in the atmosphere is much higher than that of traditional Silicon materials, and its structure and electronic properties are maintained. This result was recently published in Advanced Materials and ACS Central Science. The first authors of the article were Dr. Zhuangjin and Dr. Li Zhi of Wulungong University.

In addition, the Silicon atoms and calcium atoms in the silicene prepared by the solid-phase method are arranged alternately to form a layered structure, and calcium is removed by means of a local chemical intercalation, and independent substrates of silicene are obtained. Silicene prepared by this chemical method is a cathode of lithium batteries, and has the advantages of high capacity of silicon-based materials and good recycling characteristics of graphite materials, making it a very promising negative electrode material for lithium ion batteries.

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