High-specific-capacity materials are crucial for the high-energy-density lithium-ion secondary batteries as the automakers and customers are both eager to extend the cruising range of electric vehicles. The current commercial silicon/carbon composites are based on the mechanical mixture of silicon and graphite, but this weak combination is not suitable for the higher-capacity materials. Here, low-cost raw materials are used for the preparation of a graphite/silicon@carbon composite negative electrode material, which synergizes ball milling, molten salts electrolysis and carbon coating. Silica is in situ electrochemically reduced to silicon on the flaky graphite serving as the conducting substrate during the electrolysis process. It is found that ball milling increases the active sites on the basal plane of graphite, which is beneficial for the nucleation and growth of the silicon, and enhances the bonding of silicon particles and graphite. As for the electrochemical results of coin-type cells, this graphite/silicon@carbon composite material exhibits a better cycle performance than the commercial Si/C 650 silicon-based composite material.

中文翻译：

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熔盐电解制备锂离子电池用石墨/硅@碳复合材料

高比容量材料对于高能量密度锂离子二次电池至关重要，因为汽车制造商和客户都渴望扩大电动汽车的续航里程。目前商业化的硅/碳复合材料是基于硅和石墨的机械混合物，但这种弱组合不适用于更高容量的材料。在这里，低成本的原材料被用于制备石墨/硅@碳复合负极材料，其协同球磨、熔盐电解和碳涂层。在电解过程中，二氧化硅在作为导电基材的片状石墨上被原位电化学还原为硅。发现球磨增加了石墨基面上的活性位点，有利于硅的成核和生长，增强硅颗粒与石墨的结合。至于纽扣电池的电化学结果，这种石墨/硅@碳复合材料比市售的 Si/C 650 硅基复合材料表现出更好的循环性能。