| With the progress of technology and the improvement of demand for electronic products, portable electronic devices diversified development. As wearable electronic devices appearing, the power storage devices of these products also need to become lighter, more efficient and flexible. In this paper,based on the research results of lithium ion battery flexible electrode,graphene self-standing paper and carbonized electrospinning nanofiber membrane are prepared as flexible anode electrodes. These electrodes not only play the current collctor's role but also have the ability of storing lithium ions.This work tried to explore the best molding process, and afterward to do further doping with metal oxide which has high specific capacity. These doped materials have the enhanced electrochemical performance because of the synergistic effect of different materials. Then the flexible self-standing electrode with outstanding specific capacity are produced, which dosen't include any collector, conductive agent or polymer adhesive. This molding process needs no grinding and coating as traditional process, which could guarantee the structural integrity of the materials. Some column characterization tests were performed on the materials such as the SEM?XRD?XPS?FT-IR?TGA. The electrochemical performance of the self-standing electrodes also been tested. The research contents are as follows:(1) Electrochemical intercalation method combined with Hummers method to prepare large-scale graphene oxide with a diameter more than 0.3 mm. Compared of several film-forming processes, the graphene flexible electrode material prepared by "Freeze-drying and Lamination" method is not only the best in structural performance, but also has high production efficiency.The initial specific capacity of the graphene at the initial density of 0.1 A·g-1 is 582 mA h·g-1. The hollow Sn02 with spherical diameter of 500 nm, spherical shell thickness of 50 nm and particle size uniformity are synthesized by hydrothermal synthesis. Use this new method and mix the hollow Sn02 microspheres with the large size graphene oxide solution after by the freeze-drying and lamination method getting a hollow Sn02/graphene flexible self-standing electrod. As much as possible to increase the content of hollow Sn02 on the basis of ensuring the electrode's self-standing performance.We've got the HSN-30 which has a highest SnO2 content up to 63% and the optimum performance. The initial discharge capacity is as high as 1355.9 mA h·g-1, and the first charge capacity is up to 930.5 mA h·g-1. After 100 cycles,the specific capacity of this electrode still remains as 556.7 mA h·g-1. This new process provides a feasibility guide for other nano-active materials and graphene doped flexible electrode's preparation.(2) An amorphous nano-carbon fiber membrane (CNF) with flexibility is prepared by solidification and carbonization of polyacrylonitrile (PAN) by electrospinning. It can be used as the anode electrode for lithium ion battery all by itself. For the first time at 0.1 A·g-1 current density, the specific capacity of first discharge is 657 mA h·g-l, and the specific capacity remains as 398 mA h·g-1 after 100 cycles. Add the cobalt acetate as Co3O4's precursor to the spinning solution to get the CNF/Co3O4 electrodes. The result shows that the CNF5-Co-700 with the carbonization temperature is 700 ? and the ratio 5/1 of PAN/cobalt acetate performs the most excellent performance after compared different doping contents and different carbonization temperature.Carbonization process helps to form amorphous Co304, which disperses in the nano-fiber evenly. This material has excellent self-supporting ability and a certain flexibility that can be bent. As the lithium anode material, the first discharge capacity is as high as 977.7 mA h·g-1 at the certain current density of 0.1 A·g-1. The first coulomb efficiency is 80%. The specific capacity after 30 cycles still maintain 621.2 mA h·g-1. |
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