Fig. 1.a) Schematic diagram of the silicon oxide stripping process, b) Schematic diagram of the molecular structure of siloxyethylene, c) Microstructure of carbon-coated 2-D nano silicon/silicon dioxide composite nano anode material Figure 2. High-rate performance comparison of 2-D nano-silicon/silicon dioxide composite negative electrode materials reported in the literature and silicon-based negative electrode materials reported in the literature. Figure 3. Cyclic stability of two-dimensional nano-silicon/silica composite anode material Figure 4. Schematic diagram of two-dimensional nano-silicon/silica composite materials used in long battery life electric vehicle battery Compared with the traditional graphite anode material (372mAh/g), the silicon anode material has a very high theoretical specific capacity (3580mAh/g) and is the first choice for high-energy-density lithium ion battery anode materials. However, the silicon anode material has a volume change (up to 3 times or more) during the charge-discharge cycle, resulting in powdering of the silicon particles, which results in the repeated regeneration of the SEI film, low Coulomb efficiency, and increased polarization of the electrical contact, resulting in an actual silicon negative electrode material. The cycle life and rate performance are poor. The Lithium Battery Engineering Laboratory of Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, has carried out research and development of silicon-based anode materials since 2011 and has made a series of progress. In 2012, a three-dimensional porous nano-silicon/graphene composite anode material was reported. Recently, a new 2D nano-silicon/silicon dioxide composite negative electrode material (2D nano-Si/SiO2) has been reported. This work utilizes the topological transformation of the CaSi2 layered structure, which chemically strips Ca atoms in an acidic solution (Fig. 1a) leaving a monoatomic layer of wrinkled silylene. Since the Si atoms only have sp3 hybridization, the silylene is extremely unstable. Oxidation in an aqueous solution results in a metastable two-dimensional silicone (Fig. 1b). The two-dimensional silicone is dehydrated by suitable heat treatment conditions to obtain a two-dimensional nano-silicon/silicon dioxide composite negative electrode material (2D nano-Si/SiO2). Nanosilicon is uniformly dispersed in amorphous silicon oxide (Fig. 1c). The two-dimensional structure can effectively reduce the lithium ion migration distance. Nano-silicon and silicon oxide can effectively reduce the volume expansion rate. Therefore, 2D nano-Si/SiO2@C prepared by this method shows excellent cycle stability and rate performance. Electrochemical performance tests showed that the initial discharge capacity was greater than 950 mAh/g at 0.15 A/g, and the discharge capacity was 360 mAh/g at a high current density of 7.5 A/g, compared to silicon or silicon reported in the literature. In the oxide materials, the rate performance has significant advantages (Fig. 2); at high current densities of 1.5, 3.0, and 7.5 A/g, the 300-cycle capacity retention rates were 73%, 73%, and 92%, respectively (Figure 3). The new 2D nano-Si/SiO2@C anode material is expected to be used in long-life electric vehicles (Figure 4). This work was published on Nano Energy under the title of Two-dimensional silicon suboxides nanostructures with Si nanodomains confined in amorphous SiO2 derived from siloxene as high performance anode for Li-ion batteries. The research work was supported by the national key R&D projects, the National Natural Science Foundation of China, the key deployment projects of the Chinese Academy of Sciences, the pilot project of the Chinese Academy of Sciences, and the Ningbo Graphene Applied Technology R&D project. Galvanized Welded Wire Mesh,Welded Wire Mesh Fence,Garden Welded Mesh,Welded Wire Mesh Galvanized Shenzhou City Hongda Hardware Products Co.,Ltd , https://www.hdgabion.com
