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CNTs/Si/C——New Hope for High Energy Lithium Ion Battery Anode Materials

2018-07-25 来源:亚科官网
  Recently, researchers from China University of Mining and Technology, Georgia Institute of Technology, Shenzhen University, and Shenzhen Graduate School of Tsinghua University collaborated to synthesize sandwich structure CNTs/Si/C materials by hydrothermal method and magnesia method for lithium ion battery anodes, which showed excellent electrochemical performance. Related research results are published in the article "Sandwich-like CNTs/Si/C nanotubes as high performance anode materials for lithium-ion batteries" [1] in the internationally renowned journal Journal of Materials Chemistry A.
  Lithium-ion batteries are considered to be power supplies that meet the increasing energy demands of portable electronic devices, electric and hybrid vehicles due to their high capacity and stable cycle life. Anode material is one of the key links. As the main anode material, graphite anodes have been widely used, but their capacity is close to the theoretical capacity and it is difficult to improve. Silicon-based anode materials have higher specific capacity and energy density and are considered to be the most promising anode materials for next-generation lithium-ion batteries. However, such a negative electrode material generates a large volume change during the charge and discharge cycle, resulting in pulverization of the electrode material and collapse of the conductive network, thereby drastically attenuating the cycle performance.
  In this study, the researchers used nitrate-treated carbon nanotubes as a template and tetraethyl orthosilicate as raw materials to successfully synthesize coaxial silicon-coated carbon nanotubes (CNTs) by hydrothermal method and magnesium thermal reduction method(CNTs/Si). CNTs/Si/C sandwich composite structure was obtained after further carbon coating. Among them, the conductivity and excellent mechanical properties of the one-dimensional carbon nanotubes can alleviate the stress caused by the volume change during charging and discharging and improve the conductivity of the silicon-based anode material, and the sandwich tubular structure increases the contact area between the electrolyte and the anode material. The lithium ion diffusion path is shortened, and the outer carbon layer is easy to form a stable SEI film with the electrolyte.
  CNTs/Si/C as an anode material in lithium ion batteries exhibits excellent cycle performance. When the current density is as high as 500mAg-1, the reversible discharge can be stabilized up to 1508.5mAhg-1 after 1000 cycles with no observable structural changes during the charge/discharge process during charge and discharge. At higher current densities, CNT/Si/C nanotubes also exhibit desirable cycling performance.
  The test results show that the sandwich structure CNT/Si/C material has good electrochemical stability and safety performance, and is expected to be used as a negative electrode material for lithium ion batteries in the future.
[1] Ruiping Liu, Chao Shen, Yue Dong, Jinlei Qin, Qi Wang, James Iocozzia, Shiqiang Zhao, Kunjie Yuan, Cuiping Han, Baohua Li, Zhiqun Lin. Sandwich-like CNTs/Si/C nanotubes as high performance anode materials for lithium-ion batteries. Journal of Materials Chemistry A, 2018, DOI:10.1039/c8ta04686g.
Edited by Suzhou Yacoo Science Co., Ltd.