Department of Materials Physics and Chemistry, School of Materials Science and Engineering, Beijing Institute of Technology, Beijing 100081, People's Republic of China.
Nanotechnology. 2017 Apr 21;28(16):165404. doi: 10.1088/1361-6528/aa63a1. Epub 2017 Mar 24.
Silicon is a promising alternative anode material since it has a ten times higher theoretical specific capacity than that of a traditional graphite anode. However, the poor cycling stability due to the huge volume change of Si during charge/discharge processes has seriously hampered its widespread application. To address this challenge, we design a silicon hollow sphere nanostructure by selective etching and a subsequent magnesiothermic reduction. The Si hollow spheres exhibit enhanced electrochemical properties compared to the commercial Si nanoparticles. The initial discharge and charge capacities of the Si hollow sphere anode are 2215.8 mAh g and 1615.1 mAh g with a high initial coulombic efficiency (72%) at a current density of 200 mA g, respectively. In particular, the reversible capacity is 1534.5 mAh g with a remarkable 88% capacity retention against the second cycle after 100 cycles, over four times the theoretical capacity of the traditional graphite electrode. Therefore, our work demonstrates the considerable potential of silicon structures for displacing commercial graphite, and might open up new opportunities to rationally design various nanostructured materials for lithium ion batteries.
硅是一种很有前途的替代阳极材料，因为它的理论比容量是传统石墨阳极的十倍。然而，由于 Si 在充放电过程中的巨大体积变化，其循环稳定性较差，严重阻碍了其广泛应用。为了解决这一挑战，我们通过选择性刻蚀和随后的镁热还原设计了硅空心球纳米结构。与商业硅纳米颗粒相比，硅空心球表现出增强的电化学性能。硅空心球阳极的初始放电和充电容量分别为 2215.8 mAh g 和 1615.1 mAh g，在 200 mA g 的电流密度下具有 72%的高初始库仑效率。特别是，在 100 次循环后第二次循环的可逆容量为 1534.5 mAh g，容量保持率为 88%，是传统石墨电极理论容量的四倍多。因此，我们的工作证明了硅结构在取代商业石墨方面具有相当大的潜力，并可能为锂离子电池的合理设计各种纳米结构材料开辟新的机会。
