【摘要】 通过对氧化硅预处理得到多组分硅pSi（Si、SiO、SiO₂）,再利用化学气相沉积法（CVD）设计了具有核壳结构的pSi与碳纳米纤维（CNF）的复合材料（pSi-CNF）。多组分硅中Si、SiO提供电化学可逆容量,SiO₂可以抑制硅的体积膨胀;碳纳米纤维包覆形成的壳层结构可以有效提高复合材料的导电性,同时进一步抑制硅的体积膨胀保持核壳结构的完整。通过SEM、TEM、EDS、XRD、Raman和XPS对复合物的微观结构进行分析。结果表明:pSi-CNF的粒径为5～20μm,碳纳米纤维的直径为5～40 nm, pSi-CNF复合材料中含有Si、SiO和SiO₂多种组分硅,有明显特征峰;碳纳米纤维均匀包覆于硅表面,形成核壳结构。电化学性能测试表明,在0.2 A·g^-1的电流密度下,经100次循环后其可逆容量为1 411 mAh·g^-1,容量保持率为74%,具有良好的循环稳定性和较高的可逆容量;在1 A·g^-1的电流密度下,经300次循环后其可逆容量为735 mAh·g^-1,容量保持率为86%,且具有良好的倍率性能。更多还原

【Abstract】 Multi-component porous Si-SiO_x（pSi） consisting of Si, SiO and SiO₂ was formed by the pretreatment of SiO at 950℃ for 3 h in an inert atmosphere（He） using a disproportionation reaction. Hybrids of pSi and carbon nanofibers（pSi-CNFs） with a core-shell structure were prepared by catalytic chemical vapor deposition（CVD） using Fe-Ni species as the catalyst and a mixture of CO/H₂/C₂H₄（volumetric ratio 3∶1∶1） as the reactant for 0.5, 1 and 2 h, and were characterized by SEM, TEM, EDS, XRD, Raman spectroscopy and XPS. Results indicate that the pSi-CNF particle sizes are 5-20 μm with the diameters of the CNFs being 5-40 nm.The CNFs are uniformly coated on the surface of the pSi to form a core-shell structure. Electrochemical performance testing shows that the reversible capacity of the pSi-CNF（0.5 h） remains at 1 411 mAh·g^-1 and the capacity retention is 74% after 100 cycles at a current density of 0.2 A·g^-1. The reversible capacity remains at 735 mAh·g^-1 at a current density of 1 Ag^-1 after 300 cycles with a capacity retention of 86%. In the pSi, Si and SiO provide the electrochemical reversible capacity. The core-shell structure with the CNF coating effectively improves the conductivity of the composites, and also inhibits the volume expansion of silicon to maintain the integrity of the core shell structure.更多还原