多孔硅/碳复合负极材料的制备及电化学性能

以介孔二氧化硅SBA-15为硅源, 采用镁热还原法和化学气相沉积(CVD)法合成了具有莲藕状结构的多孔硅/碳复合材料。利用X射线衍射仪(XRD)、扫描电子显微镜(SEM)、透射电子显微镜(TEM)和氮气吸脱附法研究了原料配比, 混压方式以及反应温度对多孔硅物相组成和结构形貌的影响。多孔硅的最佳合成条件为: 镁粉过量20wt%, 原料经球磨混合均匀后直接在750℃下高温反应4 h。对多孔硅及多孔硅/碳材料进行了电化学性能测试, 在0.5 A/g电流密度下循环70次后仍保持1633.1 mAh/g的可逆容量, 并且在8 A/g下容量达到580.1 mAh/g, 表现出优异的循环稳定性以及倍率性能。

Preparation and Electrochemical Properties of Porous Silicon/Carbon Composite as Negative Electrode Materials

Lotus root-like porous silicon / carbon composite was synthesized via magnesiothermic reduction and chemical vapor deposition (CVD) method, using mesoporous silica SBA-15 as silicon source. X-ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscope (TEM) and nitrogen adsorption-desorption measurements were used to study the effects of the raw material ratio, mixing-pressing method and reaction temperature on the phase composition and morphology of the lotus root-like porous silicon. The optimal synthesis condition of porous silicon is that the uniformly mixed precursors with the excess amount of 20wt% Mg powder after ball-milling are directly reacted at 750℃ for 4 h. The electrochemical tests reveal the porous silicon/carbon composite material maintains the reversible capacity of 1633.1 mAh/g at a current density of 0.5 A/g after 70 charge-discharge cycles, and attains 580.1 mAh/g even at 8 A/g.