Electrochemical Lithiation and Sodiation of Nb-Doped Rutile TiO₂

Abstract

As anode materials of Li-ion and Na-ion batteries, the electrochemical insertion/extraction reactions of Li and Na were investigated for a rutile-type Nb-doped TiO2 synthesized by a sol–gel method. We changed the particle and crystallite sizes of the Nb-doped rutile TiO2 powders by annealing at various temperatures between 100 and 1000 °C and prepared thick-film electrodes consisting of the powders. The anode performances were remarkably improved not only in the Li-ion battery but also in the Na-ion battery with a reduced annealing temperature of 400 from 1000 °C. We revealed that the Nb-doped TiO2 showing better high-rate performances exhibited a larger ratio of crystallite size to particle size. The size-dependent enhancement in the performance of rutile TiO2 was much more drastic than that of anatase TiO2. These results suggest that rutile’s potential diffusivity of Li and Na appeared more obviously when increasing the ratio because its diffusion coefficient is anisotropic and significantly high.

Hierarchical Porous Nanosheets Constructed by Graphene‐Coated, Interconnected TiO2 Nanoparticles for Ultrafast Sodium Storage

“…Representative intercalation anodes include disordered carbons, Ti‐based oxides (TiO 2 , Na 2 Ti 3 O 7 , and Li 4 Ti 5 O 12 ), and niobium pentoxide . Since Ti‐based oxide materials were proposed as anode materials for SIBs in 2011, great efforts have been devoted to developing different strategies to prepare polymorphic TiO 2 ‐based structures . For example, Myung and co‐workers synthesized carbon‐sheathed anatase‐TiO 2 nanorods to improve the rate capability .…”

Insertion of Mono- vs. Bi- vs. Trivalent Atoms in Prospective Active Electrode Materials for Electrochemical Batteries: An ab Initio Perspective

“…Our estimated voltage for magnesiation of the anatase phase (about 0.9 V, note that the numbers in Figure 9 are for defect formation energies and expected voltage is −E f /q) was shortly after confirmed experimentally [113]. For cases where there were no measurements or where the experimental results in different publications are contradictory (e.g., Na in rutile where both activity and lack of activity were reported [108,109,111]), our calculations provided practically useful information on the contribution to voltage due to the properties of the material itself, which is not directly accessible in experiments which compound contributions from interfaces, nanosizing, binders etc. An important finding is that amorphization of TiO 2 strengthens binding of Li, Na, and Mg vs any crystalline phase and can be used to control voltage.…”

“…We have produced the first comparative computational study [22] of Li, Na, and Mg interaction with four phases of titania which are intensely studied by experimentalists as potential electrode materials: anatase, rutile, (B), and amorphous TiO2 [39,[100][101][102][103][104][105][106][107][108][109][110][111][112]. Interaction energies were mapped for the first time among the three types of inserted metal atoms and four phases.…”

Improved conductivity and ionic mobility in nanostructured thin films via aliovalent doping for ultra-high rate energy storage

“…15 Specically, in comparison to other TiO 2 polymorphs, TiO 2 's anatase crystal structure possesses a good balance of stability and theoretical capacity (335 mA h g À1 ). [16][17][18] However, TiO 2 's relatively low intrinsic electronic conductivity and Li + mobility signicantly hinder its high-rate performance. [19][20][21] A variety of TiO 2 morphologies, such as solid particles, 22 hollow particles, 23 bers, 24 tubes, 25 rods, 26 and sheets, 20 have been investigated, all of which have shorter Li + diffusion lengths and enhanced 1dimensional (1-D) charge transport.…”