多孔硅/硅钛合金的制备及在锂离子电池负极上的应用

Preparation and electrochemical properties of Si/Si-Ti alloy nanoparticle composites as anode materials for lithium-ion batteries

以钛掺杂介孔二氧化硅SBA-15为前驱体,用镁热还原法制备多孔硅/硅钛合金复合材料。采用X射线衍射(XRD)、扫描电镜(SEM)、透射电镜(TEM)和红外光谱(FT-IR)等方法对复合材料进行表征;利用恒电流充放电对复合材料作为锂离子电池负极材料的电化学性能进行分析。结果表明,多孔结构为体积膨胀提供了缓冲空间,硅钛合金的存在起到支撑骨架的作用,同时一定程度上改善了负极材料的导电性,多孔硅/硅钛合金复合材料具有较好的循环稳定性,0.1C循环50圈后可逆容量为801mAh/g,倍率性能也较单质硅材料大大提高,1C倍率下放电容量为618.9mAh/g。

A series of porous Si/Si-Ti alloy were prepared by magnesium reduction process with Ti-containing silica molecular sieves(Ti-SiO_2)as the precursor.The morphologies and structures of Si/Si-Ti alloy were characterized by X-ray diffraction(XRD),scanning electron microscopy(SEM),transmission electron microscopy(TEM)and Fourier transform infrared spectroscopy(FT-IR).The electrochemical properties of the composites as anode materials for lithium-ion batteries were evaluated by Galvanostatical text.The results show that the effect of volumetric expansion wasrelieved because porous structure provides sufficient buffer space.In addition,the existence of Si-Ti alloy improved the conductivity of the composite materials.The sample achieved remarkable electrochemical performance with a capacity of 801mAh/g at 420mA/g after 50 cycles.