The effect of Ti-based surface layer on AlSi thin film as a high-performance anode for the lithium-ion battery

Abstract

Significant volume changes during cycling and the instability of the solid electrolyte interphase (SEI) are the main challenges that limit the practical application of silicon-based anodes. TiN and TiO2 were selected as surface layers and deposited on the HCl-etched AlSi (AlSi’) thin films by atomic layer deposition (ALD) to enhance the electrochemical performance of the anode. The surface layers with excellent mechanical strength can effectively suppress the volume expansion of the AlSi thin film and maintain excellent electrical contact between the film and the substrate during cycling. The effects of TiN and TiO2 surface layers on the composition and growth of the SEI layer on the AlSi’ film anode have been discussed in detail. The TiO2 surface layer was found to inhibit the continuous growth of the SEI layer and promote the formation of a mechanically robust and stable SEI layer. The AlSi’/TiO2(8 nm) anode shows a high initial discharge capacity of 2802 mA h g-1 with an initial coulomb efficiency (ICE) of 88% at 0.8 A g-1, and it maintains a capacity retention rate of 83% after 500 cycles. Moreover, the AlSi’/TiO2(8 nm) anode exhibits outstanding rate performance, as it sustains a capacity of 1710 mA h g-1 after 500 cycles at 5 A g-1, and maintains a capacity above 1032 mA h g-1 even at 30 A g-1.