硅用作锂离子电池的负极材料,有着超高的理论比容量(4200mAh/g)、较低的嵌脱锂电位。采用海藻酸钠(SA)和葡萄糖(GLU)作为复合碳源,添加五氧化二铌(Nb₂O₅)和分散剂进行包覆改性纳米硅,制得的硅碳复合材料与石墨负极材料混合后得到Si@SA-C。X射线衍射测试表明Si@SA-C具有很强的石墨和硅的特征衍射峰,没有无定型碳的杂峰。Si@SA-C的首次放电比容量为564.4mAh/g,首次充电比容量为320.2mAh/g,首次充放电效率为56.7%。添加Nb₂O₅改性材料Si@SA/NO-G的首次放电比容量为658.4mAh/g,首次充电比容量为413.5mAh/g,首次充放电效率为62.8%,在首次充放电比容量和效率方面均有显著提升。添加聚乙烯吡咯烷酮(PVP)材料Si@SA/NO/PVP-G的首次放电比容量为689.7mAh/g,首次充电比容量为446.2mAh/g,首次充放电效率为64.7%,在首次充放电比容量和效率方面进一步得到提升。

Silicon is used as a negative electrode material for lithium-ion batteries,which has an ultra-high theoretical specific capacity (4200mAh/g) and a low intercalating and deintercalating lithium potential.Sodium alginate (SA) and glucose (GLU) were used as composite carbon sources.Bismuth pentoxide and dispersant were added to coat the modified nano-silicon.The prepared silicon-carbon composite material was mixed with graphite anode material to obtain Si@SA-C.XRD tests shown that Si@SA-C had strong characteristic diffraction peaks of graphite and silicon,and there was no impurity peak of amorphous carbon.Si@SA-C had a first discharge specific capacity of 564.4mAh/g,a first charge specific capacity of 320.2mAh/g,and a first charge and discharge efficiency of 56.7%.The initial discharge specific capacity of Si@SA/NO-G was 658.4mAh/g,the first charge specific capacity was 413.5mAh/g,and the initial charge and discharge efficiency was 62.8%.The silicon-carbon material doped with antimony pentoxide had a significant improvement in the first charge-discharge ratio capacity and efficiency.The initial discharge specific capacity of Si@SA/NO/PVP-G with polyvinylpyrrolidone (PVP) was 689.7mAh/g,the first charge specific capacity was 446.2mAh/g,and the first charge-discharge efficiency was 64.7%.It was further improved in terms of first charge-discharge ratio capacity and efficiency.