Novel approach for improving the performance of Si-based anodes in lithium-ion batteries

Herein, we report successful deposition of aluminum oxide films on the silicon nanowires (SiNWs) to realize core-shell silicon-based lithium-ion battery anodes. By means of reactive ion etching, it has been possible to form an ultra-thin layer of Al₂O₃ on SiNWs through hydrogen plasma. This deposition technique leads to the formation of tiny holes on the surface of the Al₂O₃ layer while introducing the pore sites into the inner silicon material without damaging the whole structure. SiNW@Al₂O₃ core-shell nanostructures were used as the effective anode materials and showed a superior electrochemical performance compared to conventional SiNWs. Our electrode exhibited the high first cycle specific discharge capacity of 3936 mAh g^-1 at a rate of C/16 as well as high rate capability. Furthermore, this anode electrode showed less than 6% degradation of specific capacity over 120 cycles at high rate density of 2C and it delivers high reversible capacity of 965 mAh g^-1. The improvement in the electrochemical properties of our electrode is achieved due to both a high specific capacity of Si core and the effect of aluminum oxide shell on active material cycling stability.