Zhu Hongzheng, Shiraz Mohammad Hossein Aboonasr, Liu Liang, Hu Yuhai, Liu Jian
School of Engineering, Faculty of Applied Science, University of British Columbia, Kelowna, BC, V1V 1V7, Canada.
Automotive Engineering Research Institute, Jiangsu University, Zhenjiang, 212013, People's Republic of China.
Nanotechnology. 2021 Apr 2;32(14):144001. doi: 10.1088/1361-6528/abd580.
Graphite/silicon (G/Si) composites are considered as possible alternative anode materials to commercial graphite anodes. However, the unstable solid electrolyte interphase (SEI) on G/Si particles results in rapid capacity decay, impeding practical applications. Herein, a facile and low-cost AlO coating was developed to fabricate stable artificial SEI layers on G/Si composites. The amorphous AlO coating with a thickness of 10-15 nm was synthesized by a simple sol-gel method followed by high-temperature annealing. The AlO coated G/Si anode delivers an initial discharge capacity of 540 mAh g at 25 °C and has improved Coulombic efficiency and cycling stability. After 100 cycles, the capacity retention is 76.4%, much higher than the 56.4% of the uncoated anode. Furthermore, the AlO coating was found to be more effective at improving the stability of G/Si at a higher temperature (55 °C). This was explained by the AlO coating suppressing the growth of SEI on Si/G and thus reducing the charge transfer resistance at the G/Si-electrolyte interface. It is expected that the AlO coating prepared by the sol-gel process can be applied to other Si-based anodes in the manufacture of practical high-performance lithium-ion batteries.
石墨/硅（G/Si）复合材料被认为是商业石墨负极可能的替代负极材料。然而，G/Si颗粒上不稳定的固体电解质界面（SEI）导致容量快速衰减，阻碍了其实际应用。在此，开发了一种简便且低成本的AlO涂层，以在G/Si复合材料上制备稳定的人工SEI层。通过简单的溶胶-凝胶法，随后进行高温退火，合成了厚度为10-15nm的非晶AlO涂层。AlO涂层的G/Si负极在25°C下的初始放电容量为540mAh g，并且具有提高的库仑效率和循环稳定性。100次循环后，容量保持率为76.4%，远高于未涂层负极的56.4%。此外，发现AlO涂层在更高温度（55°C）下更有效地提高了G/Si的稳定性。这可以解释为AlO涂层抑制了Si/G上SEI的生长，从而降低了G/Si-电解质界面处的电荷转移电阻。预计通过溶胶-凝胶法制备的AlO涂层可应用于实际高性能锂离子电池制造中的其他硅基负极。
