Reducing Crystallinity of Micrometer-Sized Titanium–Niobium Oxide through Cation Substitution for High-Rate Lithium Storage

Abstract

As promising anode materials for lithium-ion batteries, titanium− niobium oxides still suffer from the bottleneck of ion transport, which severely limits their practical usage. In this work, the ion-transport kinetics of micrometersized Ti 2 Nb 10 O 29 is improved by crystallinity mediation. The crystallinity of Ti 2 Nb 10 O 29 is intrinsically reduced through cation substitution (Nb 5+ → Ti 4+ and W 6+ ), with Ti 2.5 Nb 9 W 0.5 O 29 obtained. The amorphous phases not only optimize the ion transport through isotropic ion diffusion path but also introduce more oxygen vacancies, which can serve as nucleation sites for phase changing and improve electron conductivity. As a result, Ti 2.5 Nb 9 W 0.5 O 29 exhibits superior kinetics and remarkable rate performance. Even with large particle sizes from 5 to 20 μm, Ti 2.5 Nb 9 W 0.5 O 29 can achieve a reversible specific capacity of 110 mAh g −1 at a high current density of 10 A g −1 , much higher than Ti 2 Nb 10 O 29 (11.1 mAh g −1 ). This work provides a novel view for the development of practical, high-performance anode materials for LIBs.

Oxygen Defect and Cl–-Doped Modulated TiNb2O7 Compound with High Rate Performance in Lithium-Ion Batteries

“…This is attributed to the additional active sites and disordered structure of the amorphous phase. 62,63 Capacitance and diffusion contributions are also calculated, as shown in Figure 7c,f. With an increase in the scanning rate, the capacitance contribution will increase, while the diffusion contribution decreases gradually.…”

Fast and Durable Lithium Storage Enabled by Tuning Entropy in Wadsley–Roth Phase Titanium Niobium Oxides

“…The cycling stability of FTNO‐1000 is also competitive compared to the other micro‐sized Wadsley–Roth phase oxides previously reported (Figure 3g). [ 3–5,23,24 ] These results indicate the positive effect of iron substitution on stabilizing the structure during extensive cycling. Given the fact that the structural stability of the host mainly depends on the lattice evolution behavior during the repetitive insertion/extraction of Li + ions, detailed in situ XRD analysis was conducted and will be discussed later.…”

“…As shown in Figure 3c, the three electrodes display similar capacities at a relatively low C‐rate. However, compared to FTNO‐1000 electrodes, the capacities of FTNO‐1100 and TNO‐1100 drop significantly when the rate increases gradually from 2 to 50 C, delivering only 48.8 and 37.9 mAh g −1 at 50 C. The superior rate ability of FTNO‐1000 is prominent among the previously reported micro‐sized TiO 2 (B), [ 47 ] Li 4 Ti 5 O 12 , [ 48 ] Ti‐Nb‐O system (Ti 2 Nb 10 O 29 , [ 7 ] Ti 2.5 Nb 9 W 0.5 O 29 [ 23 ] and Fe 0.67 Ti 0.67 Nb 10.67 O 29 [ 24 ] ) and other Metal‐Nb‐O system (Nb 16 W 5 O 55 /Nb 18 W 16 O 93 , [ 3 ] Nb 14 W 3 O 44 [ 4 ] and NiNb 2 O 6 [ 5 ] ). Moreover, it is also comparable to nanocomposite of Nb 2 O 5 with holy graphene (Nb 2 O 5 /HGF) and outperforms some nano‐sized Ti‐Nb‐O (e.g., oxygen‐defected TiNb 2 O 7 nanoparticles).…”

“…reported that the partial substitution of Nb 5+ in Ti 2 Nb 10 O 29 by Ti 4+ and W 6+ reduces the crystallinity and induces an amorphous phase in which Li + diffusion becomes isotropic resulting in enhanced ionic transport. [ 23 ] Furthermore, Lv et al. indicated that the cation‐mixing effect in the Wadsley–Roth phase is favorable for Li + diffusion and narrows the bandgap of the compound.…”

“…[19][20][21][22] On the other hand, Wu et al reported that the partial substitution of Nb 5+ in Ti 2 Nb 10 O 29 by Ti 4+ and W 6+ reduces the crystallinity and induces an amorphous phase in which Li + diffusion becomes isotropic resulting in enhanced ionic transport. [23] Furthermore, Lv et al indicated that the cation-mixing effect in the Wadsley-Roth phase is favorable for Li + diffusion and narrows the bandgap of the compound. [24] Lately, entropy tuning has received considerable interest due to the favorable entropy-dominated phase-stabilization and ionic conductivity boosting effects.…”