Bi/Bi2O3复合碳纳米纤维的制备及其储锂性能研究

为提高Bi负极材料的循环性能，提出了一种Bi/Bi₂O₃碳纳米复合纤维(Bi/Bi₂O₃-CNFs)的合成方法。以Bi₂S₃纳米棒为模板，采用静电纺丝技术及后续高温热处理方法成功合成了具有纵孔结构的Bi/Bi₂O₃(w)-CNFs。采用扫描电子显微镜(SEM)、X射线衍射(XRD)、热重分析(TGA)、透射电子显微镜(TEM)和X-射线光电子能谱(XPS)对复合材料进行了表征。讨论了不同质量分数的Bi₂S₃对复合材料结构以及电化学性能的影响。结果表明:当添加8.7%(质量分数)的Bi₂S₃时，合成的Bi/Bi₂O₃(8.7%)-CNFs拥有最佳的电化学储锂性能。当充放电电流密度为0.1 A/g时，Bi/Bi₂O₃(8.7%)-CNFs复合材料首次放电比容量可达到806 mA·h/g，并能稳定循环1 000次，即使在5.0 A/g的大电流密度下，储锂容量仍有147 mA·h/g。Bi/Bi₂O₃(8.7%)-CNFs复合结构改善了充放电过程的动力学性能，提高了电化学性能。碳纤维及内部纵孔结构缓解了充放电过程中电极材料的体积膨胀，增强了电池的循环稳定性。

The Preparation of Bi/Bi2O3 Composite Carbon Nanofiber and Its Lithium Storage Performance

In order to improve the cycling performance of Bi anode materials, a method of synthesizing Bi/Bi₂O₃ carbon nanocomposite fibers (Bi/Bi₂O₃(w)-CNFs) was proposed. Bi/Bi₂O₃(w)-CNFs with longitudinal pore structure were successfully synthesized using Bi₂S₃ nanorods as templates based on the electrospinning technique and subsequent high-temperature heat treatment. The composites were characterized with scanning electron microscopy (SEM), X-ray diffraction (XRD), thermogravimetric analysis (TGA), transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). The effects of mass fraction of Bi₂S₃ on the structure and electrochemical properties of the composites were discussed. The results showed that the synthesized Bi/Bi₂O₃(8.7%)-CNFs possessed the best lithium storage performance when 8.7%(mass fraction) of Bi₂S₃ was added. At a current density of 0.1 A/g, the Bi/Bi₂O₃(8.7%)-CNFs composites could reach 806 mA·h/g in the first cycle and be stably cycled for 1 000 cycles. Even at a high current density of 5.0 A/g, the lithium storage capacity was still 147 mA·h/g. The structure of Bi/Bi₂O₃(8.7%)-CNFs improved the kinetic performance during charging and discharging, and enhanced the electrochemical performance. The carbon fiber and the internal longitudinal tunnel structure alleviated the volume expansion of the electrode material during the charging and discharging process and enhanced the cycling stability of the battery.