石墨烯/硅负极材料的制备及其电化学性能的研究

通过将亚微米硅与石墨烯进行原位还原复合(SG1)和机械混合(SG2)这2种方式制备了不同的石墨烯/硅复合锂离子电池负极材料。SEM结果显示,2种复合物中硅颗粒都被石墨烯片层所包夹,且分散均匀;充放电测试表明,这2种复合方式均使复合电极的首次容量损失大大减小,循环稳定性得到很大提高,其首次放电比容量分别为2 070.5mAh/g和1 534.2mAh/g,循环12次后均保持在1 000mAh/g以上;通过EIS阻抗谱对硅复合电极的导电性以及电极结构的初步研究,发现复合电极本身导电性以及材料的电接触性远优于纯硅,电极结构也相对稳定。

Synthesis and electrochemical performance of the graphene/Si as the lithium ion batteries anode

Graphene/Si composites used for lithium-ion battery anode have been prepared via the re duction in situ （SG1） and mechanical mixing （SG2） methods. SEM and TEM results showed that in such two composites, silicon particles were sandwiched and dispersed in graphene layers uniformly. Charge-discharge tests revealed that the two composites significantly reduced the capacity loss for the first time and enhanced the cycling stability. After 12 cycles, the discharge was maintained above 1 000 mAh/g with the initial capacity of 2 070. 5 mAh/g and 1 534. 2 mAh/g respectly. Meanwhile, electro chemical impedance spectroscopy （EIS） was used to study the conductivity of the composite electrode and the change of electrode structure. The results demonstrated that the conductivity of composite e lectrode itself and electrical contact in the composites were far better than those of nature silicon,and the composite electrode maintained the structural integrity.