因硅具有高达4 200 mA?偸h/g的理论嵌锂容量, 成为目前最具有发展前景的锂离子电池负极材料。但是, 因硅材料在嵌脱锂过程中存在巨大的体积膨胀(≥300%), 制约了其作为锂离子电池负极的商业化应用。通过采用静电纺丝技术和碳源前驱体包覆相结合的方法, 经过碳化处理制备的C@Si/C硅基复合负极。使用X射线衍射仪、扫描电子显微镜对材料的物相结构和微观形貌进行了表征, 采用热重分析实验研究了聚乙烯吡咯烷酮包覆后所得材料质量随温度的变化情况, 通过Raman测试考察了碳化后所得硅基负极材料的石墨化程度。对所制备的硅基负极材料进行了恒电流充放电、循环伏安及交流阻抗谱分析。结果表明: 经碳包覆后的静电纺丝Si/C纤维相较于未包覆前, 电化学性能有了明显提升。在0.1 A/g的电流密度下, 首次放电容量可达到1 401.4 mA?偸h/g, 首次Coulombic效率高达70.22%, 经100圈循环后容量仍保持在582.6 mA?偸h/g, 倍率测试结果表明, 经过1.0 A/g的大电流密度测试后, 在0.1 A/g的电流密度下, 仍具有622.2 mA?偸h/g的可逆容量。

Silicon has become the most promising anode material for lithium-ion batteries since its theoretical lithium intercalation capacity is as high as 4 200 mA?偸h/g. However, its commercial application as a negative electrode for Li-ion batteries is limited due to the huge volume expansion (≥300%) during intercalation and delithiation. In this paper, a C@Si/C silicon-based composite anode was prepared by an electrospinning technique with carbon source precursor coating. The phase structure and microstructure of the material were characterized by X-ray diffraction and scanning electron microscopy. The change of the quality of the obtained material after polyvinypyrrolidone coating with temperature was investigated by thermo-gravimetric analysis. Graphite transformation degree of the silicon-based negative electrode material obtained after carbonization was determined by Raman spectroscopy. The prepared silicon-based anode materials were analyzed by galvanostatic charge-discharge, cyclic voltammetry and alternating current impedance spectroscopy. The results show that the electrochemical performance of the carbon-coated electrospun Si/C fibers is improved compared to the uncoated fibers. At a current density of 0.1 A/g, the first discharge capacity can reach 1 401.4 mA?偸h/g, the first coulombic efficiency is as high as 70.22%, and the capacity remains at 582.6 mA?偸h/g after 100 cycles. The results of rate test show that after a large current density test of 1.0 A/g, C@Si/C silicon-based composite anode still has a reversible capacity of 622.2 mA?偸h/g at a current density of 0.1 A/g.