Electrodeposition of Ag nanoparticles onto bamboo-type TiO2 nanotube arrays to improve their lithium-ion intercalation performance

Bamboo-type TiO2 nanotube arrays prepared via anodic oxidation are modified with Ag nanoparticles by pulsed electrochemical deposition, for improved lithium-ion intercalation property as the anode material in lithium-ion batteries. Heat treatment converts as-formed nanotubes into anatase for Ag deposition. Bare and Ag-modified nanotubes are cycled at a current density of 800 μAcm between 1.0 and 2.6 V (vs. Li/Li). All Ag-modified nanotubes exhibit significantly improved or even doubled areal discharge capacities and better cycleability compared to bare nanotubes. Particularly, the nanotubes modified using 100 Ag deposition cycles deliver the highest initial discharge capacity of 199.6 μAh cm and the largest final discharge capacity of 131.7 μAh cm after 50 electrochemical cycles, while bare nanotubes exhibit an initial capacity of 93.5 μAh cm and a final discharge capacity of 54.8 μAh cm. The former also exhibits 10 % higher capacity retention efficiency than the latter. In addition, an increase in the capacity of modified nanotubes is observed with more Ag deposition, but superfluous Ag content yields reduced capacities due to slower Li-ion transfer inside. Finally, kinetic characteristics of TiO2 nanotubes are explored using cyclic voltammetry to understand the origin of improvements in electrochemical properties of Agmodified nanotubes.