Niobium Alloying of Self‐Organized TiO₂ Nanotubes as an Anode for Lithium‐Ion Microbatteries

Abstract Self‐supported titanium dioxide nanotube is explored as a potential negative electrode for 3D Li‐ion (micro) batteries. Apart from the direct contact of the nanotubes with the substrate, the 1D porous structure effectively facilitates the flow of electrolyte into the bulk, alleviates any volume expansion during cycling, and provides a short lithium‐ion diffusion length. The fabrication of self‐supported Nb rich titanium dioxide nanotubes by electrochemical anodization of Ti–Nb alloys is reported. The structure, morphology, and the composition of the Nb alloyed TiO₂ nanotubes are studied using scanning electron microscopy, X‐ray diffraction, and X‐ray photoelectron spectroscopy. The electrochemical behavior of the alloyed and the pristine TiO₂ nanotubes is investigated by cyclic voltammetry, chronopotentiometry, and electrochemical impedance spectroscopy. The electrochemical performance of the pristine and the alloyed titania nanotubes reveals that as the niobium concentration increases the capacity increases. The titania nanotubes containing 10 wt% of Nb deliver a higher capacity, with good capacity retention and coulombic efficiency. Electrochemical impedance spectroscopy analysis shows that Nb alloying can decrease the overall cell impedance by reducing the charge transfer resistance.