Kim Won-Sik, Hwa Yoon, Shin Jung-Hoo, Yang Myung, Sohn Hun-Joon, Hong Seong-Hyeon
Department of Materials Science and Engineering and Research Institute of Advanced Materials, Seoul National University, Seoul 151-744, Republic of Korea.
Nanoscale. 2014 Apr 21;6(8):4297-302. doi: 10.1039/c3nr05354g.
The silicon nanostructure is a promising candidate for an anode of Li-ion batteries due to its high theoretical capacity. In this work, we have demonstrated the scalable synthesis of Si nanosheets from natural sand by magnesiothermic reduction, and suggested a new formation mechanism for Si nanosheets. In the suggested mechanism, an Mg₂Si intermediate phase was formed at an early stage of the reduction process, which leads to the two-dimensional Si nanostructure. The synthesized Si nanosheets have a leaf-like sheet morphology ranging from several ten to several hundred nanometers, and show comparable electrochemical properties to the commercial Si nanopowder as an anode for lithium ion batteries. For the improved electrochemical performance, Si nanosheets are encapsulated with reduced graphene oxide (RGO), and the RGO-encapsulated Si nanosheet electrode exhibits high-reversible capacity and excellent rate capability.
由于其高理论容量，硅纳米结构是锂离子电池阳极的一个有前途的候选材料。在这项工作中，我们展示了通过镁热还原从天然砂中可扩展地合成硅纳米片，并提出了一种硅纳米片的新形成机制。在所提出的机制中，在还原过程的早期形成了Mg₂Si中间相，这导致了二维硅纳米结构。合成的硅纳米片具有从几十到几百纳米的叶状片状形态，并且作为锂离子电池的阳极，其电化学性能与商业硅纳米粉相当。为了提高电化学性能，硅纳米片用还原氧化石墨烯（RGO）封装，并且RGO封装的硅纳米片电极表现出高可逆容量和优异的倍率性能。
