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.

Recent Progress in Understanding Ion Storage in Self‐Organized Anodic TiO2 Nanotubes

“…In both studies, the anatase structure of the doped sample was confirmed via XRD. Furthermore, a significant enlargement of the lattice parameters was determined and found to result from the incorporation of Nb 5+ and displacement of Ti 4+ in the oxide matrix . Average specific capacity values of around 160 mAh g −1 with an overall capacity retention of almost 90% after 100 cycles were found for TiO 2 NTs with a 10 wt% Nb content.…”

“…Average reversible capacity values for different types of anodic self‐organized nanotubes recorded at rates between 0.1 C and 2 C. Data collected from refs. .…”

“…Another example for enhancing the electrochemical properties of the Li‐ion anode material is represented by doping of TiO 2 NT arrays with Nb 5+ . Self‐organized Nb‐doped NTs were fabricated by anodization of Nb/Ti alloys and thermal treatment in air.…”

Optimized Spacing between TiO2 Nanotubes for Enhanced Light Harvesting and Charge Transfer

“…A general advantage of all vertically aligned nanotubes grown by anodic oxidation is that they offer a direct electron pathway to a back contact (in contrast to particle‐like nanostructures). Therefore, throughout the past decades, TiO 2 nanotubes, specifically conventional CP TiO 2 nanotubes, have been extensively studied for a wide range of applications where this direct electrode contact is beneficial, such as dye‐sensitized solar cells,, fuel cells,, Li‐ion batteries,, photocatalysts,, bio‐applications, and sensors . As SP NTs have been only recently introduced, relatively little is known about their properties – particularly their photoelectrochemical properties, in comparison to conventional close‐packed tubes.…”

Sol-Gel Processed TiO2 Nanotube Photoelectrodes for Dye-Sensitized Solar Cells with Enhanced Photovoltaic Performance

“…In regards to the replacement of the TiO 2 NP structure with alternative, TiO 2 nanotubes (NTs) for DSCs offer several advantages due to increased light scattering, fast electron transportation and reduction of trap sites compared to TiO 2 NPs [19,20]. Pristine and chemically modified TiO 2 NTs have been studied as photoelectrodes for DSCs and energy storage systems [21,22]. To the best of our knowledge, the most of publications which deal with TiO 2 NTs-based photoelectrodes report the fabrication of nanotubes by anodization of the Ti foils that is rather a complicated fabrication method [20,[23][24][25].…”