A carbon-coated Si/ graphene (Si@ C/ G) nanocomposite was prepared by dispersing a mixture containing graphene, citric acid, and Si nanoparticles in ethanol, followed by drying and carbonization at 800 ℃ for 1 h. Transmission electron microsco-py revealed that a carbon layer with a uniform thickness of ca. 2 nm was formed on the surface of the Si nanoparticles. The Si@ C nanoparticles were supported by graphene sheets with an strong interaction between them. However, the carbon layer on the Si@ C nanoparticles without the graphene addition was not uniform. This can be ascribed to the high thermal conductivity of graphene that ensures a uniform temperature distribution on the surface of the Si nanoparticles. As an anode material for lithium ion batteries, the Si@ C/ G electrode exhibits a high initial coulombic efficiency of 82. 7% and an excellent cycling stability with a capacity of 1 431 mAh·g-1 after 100 cycles at a current density of 500 mA·g-1 . Such excellent electrochemical performance is attributed to the high electrical conductivity and superior flexibility of graphene.%石墨烯、柠檬酸和硅纳米颗粒的乙醇混合物经超声分散、乙醇挥发和热处理(800℃1 h)制备出炭涂层硅/石墨烯(Si@ C/ G)纳米复合材料。透射电镜表明,Si 纳米颗粒的表面形成了一层厚度约为2 nm 的均匀炭涂层,石墨烯片层支撑着 Si@ C 纳米粒子,且两者具有较强的相互作用。作为锂离子电池负极材料,Si@ C/ G 电极具有较高的库仑效率,在500 mA·g-1的电流密度下,100卷循环后比容量为1431 mAh·g-1,表现出优越的循环稳定性。 Si@ C/ G 优异的电化学性能归因于石墨烯片层的高导热率、高导电率和优良的机械柔韧性。
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