Au nanocrystals decorated TiO2 nanotube arrays as anode material for lithium ion batteries

Abstract

In this work, we report the synthesis of TiO2 nanotube arrays with Au nanocrystals (Au@TiO2) via magnetron sputtering and thermal annealing at 450 °C. The prepared TiO2 nanotube arrays are characterized by field emission scanning electron microscopy, X-ray diffraction and transmission electron microscopy. The annealing leads to the formation of a layer of Au nanocrystals on the surface of TiO2 nanotubes and the dewetting of Au nanofilms on the top of TiO2 nanotube arrays. Using the Au@TiO2 nanotube arrays as anode material, we prepare lithium-ion half cells, and study the electrochemical performance of the lithium-ion half cells. The experimental results show that the lithium-ion half cells with the Au@TiO2 nanotube arrays prepared with the thickest Au film of 160 nm have the smallest charge-transfer resistance and the lithium-ion half cells with TiO2 nanotube arrays have the largest charge-transfer resistance. The specific capacity of the lithium-ion half cells with the Au@TiO2 nanotube arrays prepared with Au nanofilm of 120 nm is ~185 mAh·g−1, about twice of those with TiO2 nanotube arrays after 200 cycles. The Au nanocrystals in TiO2 nanotube arrays improve the cycle stability of the lithium-ion half cells with the Au@TiO2 nanotube arrays as anode material.