中文摘要：

硅作为锂离子电池负极材料具有极高的理论比容量（4200mAh/g）,是目前商业化石墨负极材料的数十倍。但是由于在充放电过程中极易发生粉化破碎,导致其循环比容量会迅速衰减。首次通过水热还原的方法制备了自支撑纳米硅/石墨烯复合纸柔性负极材料。SEM表征显示纳米硅颗粒均匀地分散在石墨烯片层中,制得的复合纸电极较纯硅纳米颗粒的电化学性能有大幅度提高,在100mA/g的电流密度下,首周放电比容量4003mAh/g,十分接近硅的理论比容量,且首周库伦效率高达91%。复合纸循环20周后比容量在3300mAh/g左右,50周后仍能维持1000mAh/g左右的比容量。这主要可归功于石墨烯纸电极优异的柔韧性和导电性,有效抑制了纳米硅颗粒的体积膨胀和结构破坏。同时水热还原法较低的还原温度保证了石墨烯纸还原前后厚度变化不大,有利于石墨烯片层与Si纳米颗粒的紧密接触。

英文摘要：

Silicon possesses an extremely high theoretical specific capacity of 4200 mAh/g, which is about more than ten times higher than that of commercial graphite, thus is a promising anode material for lithium ion batteries. However, during the charge/discharge process, Si particles pulverize and crack due to the huge volume expansion, leading to dramatic decrease on the specific capacity. This work is the first to successfully fabricate free-standing flexible nano-silicon/graphene paper electrode via hydrothermal reduction. SEM showed that Si nanoparticles are homogenously dispersed on the graphene nanosheets. The Si/rGO paper electrode exhibits a significantly improved electro- chemical performance than the pristine Si, owing to the excellent flexibility of graphene which suppresses the pulverization of Si particles as well as its excellent electrical conductivity. Moreover, the low reduction temperature enables the paper thickness unchanged after hydrothermal reduction, which facilitates the close contact between Si nanoparti- cles and graphene nanosheets. This composite paper shows an initial specific discharge capacity of 4003 mAh/g at a current density of 100 mA/g （close to the theoretical capacity of silicon）, and maintains a high specific capacity of about 3300 mAh/g after 20 cycles and 1000 mAh/g after 50 cycles.