All electrochemical process for synthesis of Si coating on TiO2 nanotubes as durable negative electrode material for lithium ion batteries

Abstract The development of high energy density Li-ion batteries requires to look for electrode materials with high capacity while keeping their stability upon cycling. In this study, amorphous silicon (a-Si) thin film deposited on self-organized TiO 2 nanotubes is investigated as negative electrode for Li-ion batteries. Nanostructured composite negative electrodes were fabricated by a two-step cost effective electrochemical process. Firstly, self-organized TiO 2 nanotube arrays were synthesised by anodizing of Ti foil. Subsequently, thanks to the use of room temperature ionic liquid, conformal Si layer was electrodeposited on the TiO 2 nanotubes to achieve the synthesis of nanostructured a-Si/TiO 2 nanotube composite negative electrodes. The influence of the Si loading as well as the crystallinity of the TiO 2 nanotubes have been studied in terms of capacity and cyclic stability. For an optimized a-Si loading, it is shown that the amorphous state for the TiO 2 nanotubes enables to get stable lithiation and delithiation with a total areal charge capacity of about 0.32 mA h cm −2 with improved capacity retention of about 84% after 50 cycles, while a-Si on crystalline TiO 2 nanotubes shows poor cyclic stability independently from the Si loading.