A facile and low-cost Al <sub>2</sub> O <sub>3</sub> coating as an artificial solid electrolyte interphase layer on graphite/silicon composites for lithium-ion batteries
Hongzheng Zhu, Mohammad Hossein Aboonasr Shiraz, Liang Liu, Yongfeng Hu, Jian Liu
Abstract
Abstract 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 Al 2 O 3 coating was developed to fabricate stable artificial SEI layers on G/Si composites. The amorphous Al 2 O 3 coating with a thickness of 10–15 nm was synthesized by a simple sol–gel method followed by high-temperature annealing. The Al 2 O 3 coated G/Si anode delivers an initial discharge capacity of 540 mAh g −1 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 Al 2 O 3 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 Al 2 O 3 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 Al 2 O 3 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.