Improved Performance of Ag-nanoparticle-decorated TiO2 Nanotube Arrays in Li-ion Batteries

The present work investigates the electrochemical response of silver nanoparticle (Ag-NP)-decorated TiO2 nanotube (NT) layers as an anode material for a lithium-ion battery. Self-organized nanotube layers with a thickness of approximately 1 mu m and a diameter of approximately 100 nm were grown by anodization of Ti in a fluoride-containing aqueous electrolyte. Ag NPs (average particle size of similar to 10 nm) were deposited both inside and outside the nanotube geometry in a well-distributed manner through a simple and efficient photocatalytic reduction process. The morphology and the chemical composition of the resulting materials were characterized by using field-emission scanning electron microscopy (FE-SEM), X-ray diffraction (XRD) and energy dispersive X-ray spectroscopy (EDX). Our results show that the TiO2 NT layers decorated with Ag NPs had a superior electrochemical response in terms of charge/discharge capacity, rate capability, cyclic performance and columbic efficiency. The enhanced performance is attributed to the improved electronic and ionic conductivity, obtained by providing highly conductive paths to electrons flowing through a well-distributed Ag NPs deposition on the walls of the highly-oriented NTs.