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 Al2 O3 on SiNWs through hydrogen plasma. This deposition technique leads to the formation of tiny holes on the surface of the Al2 O3 layer while introducing the pore sites into the inner silicon material without damaging the whole structure. SiNW@Al2 O3 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.