Department of Chemical and Chemical Engineering, Hefei Normal University, Hefei 230601, China.
Nanoscale. 2019 Sep 19;11(36):16781-16787. doi: 10.1039/c9nr05264j.
The application of Si-based anode materials is hindered by their extreme volume change, poor cycling stability, and low coulombic efficiency. Solving these problems generally requires a combination of strategies, such as nanostructure designing or surface coating. However, these strategies increase the difficulty of the fabrication process. Herein, a simple and one-pot replacement reaction route was designed to produce an Al2O3 layer anchored on mesoporous Si nanospheres (Si@Al2O3) by employing Al nanospheres with a naturally formed Al2O3 layer as a reducing agent and self-sacrificial template. The obtained Si@Al2O3 was mesoporous, with enough porous space to buffer the volume change and provide a fast lithium ion transfer channel. Furthermore, the coated Al2O3 layer could stabilize the structure and SEI layer of the mesoporous Si nanospheres, endowing the Si@Al2O3 nanospheres with improved initial coulombic efficiency, cycling performance and rate capability. As a result, a high capacity of 1750.2 mA h g-1 at 0.5 A g-1 after 120 cycles and 1001.7 mA h g-1 at 2 A g-1 after 500 cycles were delivered for lithium ion batteries. The good performance could be attributed to the mesoporous structure and the outer-coated Al2O3 layer.
硅基阳极材料的应用受到其极端的体积变化、差的循环稳定性和低库仑效率的限制。解决这些问题通常需要结合策略，如纳米结构设计或表面涂层。然而，这些策略增加了制造过程的难度。在此，通过采用具有自然形成的 Al2O3 层的 Al 纳米球作为还原剂和自牺牲模板，设计了一种简单的一锅替换反应路线，以在介孔 Si 纳米球（Si@Al2O3）上锚定 Al2O3 层。所得到的 Si@Al2O3 是介孔的，具有足够的多孔空间来缓冲体积变化并提供快速锂离子传输通道。此外，涂覆的 Al2O3 层可以稳定介孔 Si 纳米球的结构和 SEI 层，赋予 Si@Al2O3 纳米球更高的初始库仑效率、循环性能和倍率性能。结果，锂离子电池在 0.5 A g-1 下循环 120 次后可提供 1750.2 mA h g-1 的高容量，在 2 A g-1 下循环 500 次后可提供 1001.7 mA h g-1 的容量。良好的性能可归因于介孔结构和外部涂覆的 Al2O3 层。
