【摘要】 目前,锂离子电池被广泛地应用于移动电子设备、电动汽车以及混合动力汽车,因此,对高比容量以及长循环寿命的需求也愈加迫切.石墨类负极材料具有优异的循环性能,但理论比容量较低(372mA·h·g^-1),难以满足日益增长的高能量密度需求.Si负极材料因具有较高的可逆比容量(3579mA·h·g^-1)而引起广泛关注.但是,巨大的体积膨胀限制了Si负极的使用.纳米化可以有效的释放Si体积膨胀带来的应力变化,提高其电化学性能.然而,单独的纳米材料具有很高的比表面会引起诸多副反应,阻碍其实际应用.将纳米Si与石墨复合制备Si/石墨复合材料,可充分利用纳米Si和石墨的优点,有望成为新一代高能量密度和长循环寿命锂离子电池负极材料.截至目前,多种技术手段被应用于制备纳米Si/石墨的复合材料,其核心问题是保证纳米Si和石墨的均匀分散以及稳定的结合.根据石墨与纳米Si的复合过程可以将该类材料的制备方法分为:固相法、液相法、以及气相沉积法.本综述对现有文献报道的Si/石墨复合材料制备方法以及所面临的主要问题进行简要总结概括.更多还原

【Abstract】 Rechargeable lithium-ion batteries（LIBs） are recognized as the most important power supply for portable electronic devices, electric vehicle and hybrid electric vehicle. There is a continuing demand for advanced LIBs with longer life spans and higher capacity. Graphite based anode materials are now widely employed in LIBs due to their excellent cycling stability and good conductivity. However, the theoretical capacity of graphite is as low as 372 mA·h·g^-1 that is hard to meet the ever-increasing demand of high energy density LIBs. Recent years, Si based anode materials have attracted enormous attention due to its high reversible capacity(3579 mA·h·g^-1). However, the main challenge facing Si is the huge volume change during lithiation/delithiation process. It is well accepted that nanostructured Si could effectively release the strain stress caused by volume variation, thus maintaining the conductive and structural integrity of the electrode. But, the high surface area of nanostructured anode materials would result in serious side reactions between electrode materials and electrolyte, which would consume a lot of Li⁺, and leading to low coulombic efficiency. Very recently, preparation of nano-Si/graphite composite as anode for LIBs has been demonstrated as a promising high-capacity anode. The Si/graphite anode is able to take full advantages of the properties of these two materials such as the high specific capacity of nano-sized Si, mechanical flexibility and good conductivity of graphite. These beneficial features make Si/graphite hybrid composite as an ideal anode candidate for high-performance LIBs. To date, a lot of fabricating strategies have been reported to prepare Si/graphite composite. The keys and interests are focused on how to make the nanosized Si and graphite particles distributed uniformly, and how to construct a stable framework with three-dimensional conductive network. An overview of the methodologies proposed in the last decade for combining nanosized Si and graphite is summarized, which are composed of a series of technological means. Here, these methodologies are classified in three categories on basis of the composite step, including solid-state approach, liquid-phase mixture method, and chemical vapor deposition process.更多还原