Free-standing aluminium nanowire architectures made in an ionic liquid.

We report on the electrochemical synthesis of free-standing aluminium nanowire architectures through a template-assisted electrodeposition technique. For this purpose, nuclear track-etched polycarbonate membranes were employed as templates. One side of the template was sputtered with a thin gold film to serve as a working electrode. Subsequently the nanowires were made in the ionic liquid 1-ethyl-3-methylimidazolium chloride ([EMIm]Cl)/AlCl(3) (40/60 mol %) under potentiostatic conditions. Two different electrodeposition procedures were employed to fabricate strongly adherent Al nanowire structures on an electrodeposited Al layer. In the first procedure, electrodeposition simultaneously occurs along the pores of the template and on the Au-sputtered side of the template. In the second procedure, electrodeposition takes place in two different steps: first a thick supporting film of Al is deposited on the sputtered side of the membrane and second Al nanowires are grown within the pores. After chemical dissolution of the membrane in dichloromethane, an aluminium foil of a controlled thickness with a three-dimensional nanowire structure on one side was obtained. Different nanowire architectures, such as free-standing nanowires, vertically aligned tree-shaped arrays, and bunched nanowire films, were obtained. Such nanowire architectures are of particular interest for applications in Li-ion micro-batteries.