Oct 21, 2019 Pageview：23
Lithium-ion batteries are the most commonly used energy storage devices. They are widely used in smart phones, laptops and electric vehicles because of their portability, environmental friendliness and high energy density. Graphite is the most commonly used anode material. Van der Waals force between layers ensures the stability and cycle life of the material during charging and discharging. However, due to the small lattice constants, lithium ion can be intercalated in a low capacity. Finding a kind of material with high capacity and cycle stability is a hot spot in the research of lithium ion batteries.
Silene is a layered silicon material with honeycomb structure, which can be prepared by molecular beam epitaxy and solid state reaction. Because the bond length between silicon atoms in silicone is much longer than that between carbon atoms in graphene, the arrangement of interlayer atoms in silicone has warped arrangement structure. Compared with traditional silicon materials with diamond structure, the interlayer coupling effect of silicone is Van der Waals force, which provides space for lithium ion insertion between layers to ensure that the structure of silicone is not destroyed during charging and discharging, thus avoiding the problem of volume expansion of traditional silicon electrode materials during charging and discharging. Compared with graphite, the lattice constant of multilayer silicone is larger, and its theoretical capacity can reach about three times of that of graphite.
Recently, Du Yi's team at the University of Wollongong, Australia, prepared monolayer/multilayer silicone samples by molecular beam epitaxy (MBE), and studied the atomic and electronic structures of silicone in detail by scanning tunneling microscopy (STM). The results clearly show the ABA of silicone. Structure. The Dirac fermion properties of silicone were determined by angular resolved photoelectron spectroscopy. This study shows that the electrons in silicone have a very fast transmission speed and solve the problem of poor conductivity in traditional silicon materials. In addition, the study also shows that the stability of silicone in the atmosphere is much higher than that of traditional silicon materials, and its structure and electronic properties are maintained. The results were recently published in Advanced Materials and ACS Central Science. The first authors are Dr. Chuang Jincheng and Dr. Li Zhi of Wulungong University.
In addition, the silicon and calcium atoms in the silicone prepared by solid-state method alternately arranged to form a layered structure. Calcium was removed by local chemical intercalation, and then the silicone without substrate was obtained. The silicone prepared by this chemical method is used as cathode of lithium-ion batteries, and has the advantages of high capacity of silicon-based materials and good cycling properties of graphite materials. It has become a very potential negative material for lithium-ion batteries.
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