The poor structural stability and cycling coulombic efficiency (CE) of silicon–carbon composites largely limit their commercial application. In this report, a compact silicon–carbon composite with an embedded structure (Si@C) is fabricated by a facile and scalable approach. Coal tar pitch is carbonized to obtain amorphous carbon. Nano-silicon is uniformly embedded in an amorphous carbon matrix which acts as a three-dimensional conductive network. Meanwhile, no obvious interface can be observed between amorphous carbon and nano-silicon. As the anode material, the Si@C composite displays a high specific capacity of 1314.6 mA h g⁻¹ and an average CE of 99.66% from the 10th to 100th cycle. The amorphous carbon can restrain the volume variation of nano-silicon, and the structure of the Si@C composite can remain intact during cycling. The Si@C-G composite is designed, which comprises the Si@C composite and commercial graphite anode materials, to further improve the CE and make the Si@C composite suitable for lithium-ion batteries with different energy densities. The capacity of the Si@C-G composite is controlled to 669.5 mA h g⁻¹; the composite shows an initial CE of 83.76%, a high average CE of 99.88% and a capacity retention of 80.10% over 250 cycles. Besides, the full cell of Si@C-G exhibits the excellent electrochemical performance. Therefore, this Si@C composite can be developed into anode materials with high CE for lithium-ion batteries.

中文翻译：

---

一种紧凑的硅碳复合材料，具有嵌入式结构，可用于锂离子电池中的高循环库伦效率阳极材料

硅碳复合物较差的结构稳定性和循环库伦效率（CE）在很大程度上限制了其商业应用。在本报告中，通过一种简便且可扩展的方法制造了一种具有嵌入式结构（Si @ C）的紧凑型硅碳复合材料。将煤焦油沥青碳化以获得无定形碳。纳米硅均匀地嵌入无定形碳基质中，该碳基质充当三维导电网络。同时，在非晶碳和纳米硅之间没有观察到明显的界面。作为阳极材料，Si @ C复合材料显示出1314.6 mA hg ^-1的高比电容第10至第100个周期的平均CE为99.66％。非晶碳可以抑制纳米硅的体积变化，并且在循环过程中Si @ C复合材料的结构可以保持完整。设计了由Si @ C复合材料和商用石墨负极材料组成的Si @ CG复合材料，以进一步提高CE，并使Si @ C复合材料适用于具有不同能量密度的锂离子电池。Si @ CG复合材料的容量控制为669.5 mA hg ^-1; 复合材料在250个循环中的初始CE为83.76％，平均CE为99.88％，容量保持率为80.10％。此外，Si @ CG的全电池表现出优异的电化学性能。因此，该Si @ C复合材料可以开发为具有高CE的锂离子电池负极材料。