【摘要】 分别以尿素、硫脲、三聚氰胺为前聚体,采用热缩聚法在550℃下制备了3种石墨相氮化碳,与硅粉复合后合成Si@C₃N₄-u、Si@C₃N₄-t、Si@C₃N₄-m 3种材料。通过SEM、TEM、XRD、XPS、FT-IR、BET等测试方法表征了3种原材料和复合材料的形貌及晶体结构,并采用恒流充放电、循环伏安、交流阻抗等测试了复合电极的电化学性能。结果表明,以硫脲为前聚体合成的氮化碳有着更加合适的片层以及多孔结构,C₃N₄-t上残留的含S基团还能与硅颗粒能形成氢键,部分硅可以进入片层之间以及大的孔洞中,从而缓解了硅的体积效应,使电极的电化学稳定性有所提高。以硫脲为前聚体合成的氮化碳与硅复合后的材料在500 mA/g的电流密度下,充放电循环200次后,容量可以保持在971.7 mAh/g。更多还原

【Abstract】 The graphitic carbon nitride materials are prepared via direct polymerization of urea, thiourea, melamine, respectively, then Si@C₃N₄-u, Si@C₃N₄-t, Si@C₃N₄-m are synthesized by compounding with silicon powder. The morphology and crystal structure of the three raw materials and composite materials are characterized by using SEM, TEM, XRD, XPS, FT-IR and BET, and the electrochemical properties are tested by galvanostatic charge-discharge measurements, cyclic voltammetry, and electrochemical impedance spectroscopy. The results indicate that the electrochemical performance of Si@C₃N₄-t is better than Si@C₃N₄-u and Si@C₃N₄-m. C₃N₄-t has a more suitable lamellar and porous structure, and the residual groups on C₃N₄-t can form hydrogen bonds with silicon particles. Some silicon powder can enter the large pores and the gap between the layers, so the volume effect of silicon can be alleviated and the electrochemical stability of the electrode can be improved. The Si@C₃N₄-t electrode delivers a capacity of 971.7 mAh/g at a current density of 500 mA/g after 200 cycles.更多还原