Developing a practical silicon-based (Si-based) anode is a precondition for high-performance lithium-ion batteries. However, the chemical reactivity of the Si renders it liable to be consumed, which must be completely understood for it to be used in practical battery systems. Here, a fresh and fundamental mechanism is proposed for the rapid failure of Si-based materials. Silicon can chemically react with lithium hexafluorophosphate (LiPF₆) to constantly generate lithium hexafluorosilicate (Li₂SiF₆) aggregates during cycling. In addition, nanocarbon coated on silicon acts as a catalyst to accelerate such detrimental reactions. By taking advantage of the high strength and toughness of silicon carbide (SiC), a SiC layer is introduced between the inner silicon and outer carbon layers to inhibit the formation of Li₂SiF₆. The side reaction rate decreases significantly due to the increase in the activation energy of the reaction. [email protected]@C maintains a specific capacity of 980 mAh g^–1 at a current density of 1 A g^–1 after 800 cycles with an initial Coulombic efficiency over 88.5%. This study will contribute to improved design of Si-based anode for high-performance Li-ion batteries.

中文翻译：

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碳化硅作为保护层，通过抑制化学反应来稳定硅基阳极

开发实用的硅基（Si基）阳极是高性能锂离子电池的前提。然而，Si的化学反应性使其易于被消耗，必须将其完全理解才能用于实际的电池系统中。在此，提出了一种用于硅基材料快速失效的新的基本机制。硅可以与六氟磷酸锂（LiPF ₆）化学反应以不断生成六氟硅酸锂（Li ₂ SiF ₆）在循环过程中聚集。另外，涂覆在硅上的纳米碳充当催化剂以加速这种有害反应。通过利用碳化硅（SiC）的高强度和韧性，在内硅层和外碳层之间引入SiC层以抑制Li ₂ SiF ₆的形成。由于反应活化能的增加，副反应速率显着降低。[电子邮件保护] @C经过800次循环后，在1 A g ^–1的电流密度下可保持980 mAh g ^–1的比容量，初始库仑效率超过88.5％。这项研究将有助于改进高性能锂离子电池硅基负极的设计。