Evidence of Intrinsic Pseudocapacitive Lithium Intercalation in Rutile TiNbO₄

Abstract

TiNbO4 is a recently discovered Li host material. Unlike most mixed oxides of Ti and Nb, TiNbO4 does not show a phase transformation for Li storage. It stores Li-ions via a purely single-phase reaction. In this work, we show that TiNbO4 stores Li-ions via intercalation pseudocapacitance in both bulk and nanostructured states. The rate performance and capacity of TiNbO4 are independent of nanostructuring, indicating that TiNbO4 stores charges through an intrinsic pseudocapacitance mechanism.

Amorphization-Driven Lithium Ion Storage Mechanism Change for Anomalous Capacity Enhancement

“…Indeed, all the samples in the current work showed a gradual incline/decline in their voltage profiles, and no voltage plateau region was observed (Figure B–D). This result indicates the absence of a phase transformation mechanism and the presence of a pseudocapacitive Li storage mechanism, irrespective of the surface area and grain structure; this is consistent with previous reports investigating the Li storage mechanism in TNO. − …”

“…TNO powder was synthesized by a method reported previously. , Briefly, to synthesize the TNO precursor, ethylene glycol (40 mL) was taken in a 300 mL beaker and placed under stirring (500 rpm). Then, titanium butoxide (0.05 mL) and niobium ethoxide (0.04 mL) were added to ethylene glycol using a syringe.…”

“…28,29 Moreover, the rate performance of TNO is independent of the surface area and nanostructure of the particles. 28 Interestingly, while exploring the nanostructuring effect of TNO in this work, we observed that, unlike other nanostructured titanium niobium oxide families that show gradual capacity degradation over cycling, nanostructured TNO is highly stable and can even see a boost in its initial capacity over long-term cycling. However, this newly observed negative fading in TNO cannot be explained by any of the mechanisms proposed so far.…”

“…Here, we report another possible mechanism of negative fading appearing in a recently discovered anode material: TiNbO 4 (TNO). Unlike other titanium niobium oxide analogues (e.g., TiNb 2 O 7 , Ti 2 Nb 10 O 29 , TiNb 6 O 17 , and TiNb 24 O 62 ), the rutile-phased TNO is an intrinsic intercalation pseudocapacitive Li storage material, i.e., the Li storage in TNO is pseudocapacitive in nature and accompanied by bulk Faradaic processes. , Moreover, the rate performance of TNO is independent of the surface area and nanostructure of the particles . Interestingly, while exploring the nanostructuring effect of TNO in this work, we observed that, unlike other nanostructured titanium niobium oxide families that show gradual capacity degradation over cycling, nanostructured TNO is highly stable and can even see a boost in its initial capacity over long-term cycling.…”

TiNbO4‐coated industrial submicron Si anode for high‐performance Li‐ion batteries

“…Compared to previously reported TNOs, TiNbO 4 exhibited enhanced electronic because of the availability of free valence electrons in the 4d orbital and excellent ionic conductivity because of the Li + storage via the solid-solution mechanism without any phase transformations during the lithiation/delithiation. [30][31][32] These characteristics are help buffer Si expansion, as previously discussed. In this work, we reported this novel TiNbO 4 coating on nano-Si as anode LIBs materials, through which a new strategy for enhancing the cycle stability of Si anode was revealed, indicating that TiNbO 4 can be a suitable buffering material in the development of Si anode materials.…”