硅/石墨烯基自支撑薄膜的制备及电化学性能

采用简单的超声、抽滤和水合肼化学还原相结合的方法制备硅/石墨烯基自支撑薄膜，系统研究了硅含量对硅/石墨烯复合材料电化学性能的影响。结果表明：通过在石墨烯水凝胶的片层之间插入纳米硅颗粒，可以有效地控制硅体积变化，增加该复合膜的机械强度并提高其导电性。提高硅/石墨烯复合材料中硅含量的比例可以提升其可逆比容量和首次库仑效率，当硅质量分数为53%时，复合膜在0.1C倍率下的可逆比容量及首次库仑效率分别达到945.6mA·h/g和64.8%（纯硅的229倍和9倍）；继续提高硅含量的比例，可以提升其循环寿命（循环50次容量保持率60.9%、质量分数为67%的Si），但材料比容量有所下降，说明石墨烯在稳定硅基复合材料电化学性能方面发挥着非常重要作用。

Preparation and electrochemical performance of self-supporting Si/graphene films

Self-supporting Si/graphene nanocomposite films were prepared by a simple method combined with ultrasonication, filtration and chemical reduction. The effects of the ratio of Si on electrochemical performance of Si/graphene composite materials were investigated systematically. The results showed that the volume change of silicon can be effectively controlled due to the insertion of silicon between the layers of graphene, leading to the composite films with improved mechanical strength. It was found that the reversible capacity and first columbic efficiency of the composite films increased with increasing Si content. The film with 53% of Si loading showed higher reversible capacity of 492mA·h/g and better first columbic efficiency of 64.8% at 0.1C, which were 229 times and 9 times higher than pure Si, respectively. Moreover, the capacitance of these composites was 60.9% after 50 cycles when Si content was further increased to 67%, indicating that the graphene played an important role to improve the cycle performance of the composites.