Enhancing Ni-Sn nanowire lithium-ion anode performance by tailoring active/inactive material interfaces

Nanowire arrays have attracted great attention due to their great potential to improve the performance of Li-ion batteries. In this work, we studied anode performance of lithium-ion batteries using Ni-Sn nanowire arrays. A versatile method through a porous anodic alumina (PAA) template-assisted electrochemical deposition process was developed to directly synthesize Ni-Sn nanowire arrays on copper current collectors. This method presents significant advantage that the as-prepared Ni-Sn nanowire arrays can be directly used as anode electrode without any binder or conductive materials. However, the formation of a continuous Ni-Sn film at the base of the nanowires result in quick loss of electrical contact between the active material and the current collector because of the large strain mismatch at the large continuous active/inactive material (A/I) interface. By growing short Cu nanoscrews as a buffer layer before Ni-Sn nanowire growth, the formation of Ni-Sn film was inhibited and the A/I interface was scaled down to nanoscale islands. The strain mismatch is thus significantly reduced, which results in enhanced structural stability and battery performance. The effect of the composition and the length of Ni-Sn nanowire arrays on the electrochemical performance of lithium ion batteries are also systematically studied. (C) 2011 Elsevier B.V. All rights reserved.