Three-Dimensional Carbon Nanotubes Buffering Interfacial Stress of the Silicon/Carbon Anodes for Long-Cycle Lithium Storage

Silicon/graphite composites show a high specific capacity and improved cycling stability. However, the intrinsic difference between silicon and graphite, such as unequal volume expansion and lithium-ion diffusion kinetics, causes persistent stress at the silicon/graphite interface and the expansion of the electrical isolation region. Herein, carbon nanotubes (CNTs) were successfully introduced into silicon/carbon composites via ball milling and spray drying, which effectively relieved the stress concentration at the direct contact interface and formed a three-dimensional conductive structure. In addition, CNTs and amorphous carbon acting as "lubricants" further improved the inherent differences between silicon and graphite. As a result, the Si/CNTs/G@C-1 anode increased the cycling performance and rate capability, with a reversible capacity of up to 465 mAh g^-1 after 500 cycles at 1 A g^-1 and superior rate performance of 523 mAh g^-1 at 2 A g^-1. It is believed that this strategy may provide a feasible preparation of large-scale high-content silicon-based nanocomposite anodes in lithium-ion batteries.