Synthesis and performance of nanostructured silicon/graphite composites with a thin carbon shell and engineered voids
Synthesis and performance of nanostructured silicon/graphite composites with a thin carbon shell and engineered voids
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DOI：
10.1016/j.electacta.2017.10.198
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发表时间：
2017-12
影响因子：
6.6
通讯作者：
M. Ashuri;Qianran He;Yuzi Liu;S. Emani;L. Shaw
中科院分区：
文献类型：
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作者：
M. Ashuri;Qianran He;Yuzi Liu;S. Emani;L. Shaw
利用硅作为锂离子电池的负极材料一直是人们研究的主题。然而，由于硅在锂化过程中的体积变化很大，硅的电化学性能较差。在这里，我们研究了一种新颖而简单的方法来合成具有碳涂层和工程孔洞的纳米结构硅/石墨复合材料。利用高能球磨机将微米级的硅和石墨转化为纳米结构的硅/石墨复合积木，同时应用一层薄的碳涂层来封装这些复合团聚体，然后对硅进行部分刻蚀，在复合团聚体内产生工程孔洞。用这种量身定制的纳米结构制成的电池表现出比用硅纳米颗粒制成的电池更好的电化学性能，第一次循环的比容量为∼1800 mA/g−1，40次循环后的比容量为580 mA/g−1,300次循环后的比容量为350 mA/g−1。这项研究建立了一种在工业环境下可扩展的新方法，能够制备低成本的硅阳极，并且清楚地表明，在我们所研究的范围内，随着工程孔洞的增加，定制纳米结构的循环稳定性提高。
Utilizing silicon as an anode material for Li-ion batteries has been the subject of many studies. However, due to the huge volume change of silicon during lithiation, the electrochemical performance of silicon is poor. Here, we have investigated a novel yet simple approach to synthesize nanostructured silicon/graphite composites with a carbon coating and engineered voids. High-energy ball mill is employed to convert micrometer-sized silicon and graphite to nanostructured silicon/graphite composite building blocks, while a thin carbon coating is applied to encapsulate these composite agglomerates, followed by partial etching of silicon to create engineered voids inside the composite agglomerates. The batteries made with this tailored nanostructure exhibit improved electrochemical performance over the counterparts made with silicon nanoparticles and exhibited a specific capacity of ∼1800 mA h g−1discharge capacity at the first cycle, 580 mA h g−1after 40 cycles, and 350 mA h g−1after 300 cycles. This study has established a novel method scalable at industry environment and capable of producing low cost Si anodes and clearly shown that the cycle stability of the tailored nanostructure improves with increasing engineered voids in the range we have investigated.