Encapsulating Oxygen‐Deficient TiNb₂₄O₆₂ Microspheres by N‐Doped Carbon Nanolayer Boosts Capacity and Stability of Lithium‐Ion Battery

Abstract

Most of the insertion anode materials are approaching their specific capacity limitations. TiNb 24 O 62 , combining the merits of high theoretical capacity, large working potential and excellent safety, is a promising candidate for lithium-ion batteries (LIBs). However, its poor intrinsic conductivity and relatively sluggish reaction kinetics hinder its wide applications. Herein, we encapsulate the oxygen-deficient TiNb 24 O 62 microspheres by highly conductive N-doped carbon nanolayer (DTNO@NC), where TiNb 24 O 62 is purposely made to exhibit oxygen deficiency, by aerosol spray followed by co-carbonization of the electronically coupled polydopamine (PDA) coating layer. The oxygen-deficient engineering for TiNb 24 O 62 improves the intrinsic conductivity and active sites, while the PDA derived Ndoped carbon coating layer not only stabilizes the interface between the electrode and electrolyte, but also further enhances the overall conductivity. As a result, the as-fabricated DTNO@NC electrode delivers excellent Li + ion storage capacity (270 mAh g À 1 at 0.1 A g À 1) and superior cycling lifespan (capacity retention of 90 % after 1000 cycles). This work demonstrates the effectiveness of integrating an oxygen-deficient structure of intercalation-type anode material with a carbon encapsulating nanolayer in enabling the overall energy storage performance.

Enabling intercalation‐type TiNb24O62 anode for sodium‐ and potassium‐ion batteries via a synergetic strategy of oxygen vacancy and carbon incorporation

“…The crystallinity and phase formation of TNO and TNO x /rGO were confirmed by X‐ray diffraction (XRD) (Figure 1C). The diffraction patterns are consistent with the monoclinic phase of TiNb 24 O 62 as reported from the previous literature with no impure phases such as Nb 2 O 5 and other titanium niobium oxides 22,38–40 . The wrapping of rGO over TNO x does not alter the crystal structure of TiNb 24 O 62 and the additional peak positioned at 26.5° in TNO x /rGO corresponds to the (0 0 2) graphitic plane of rGO 41,42 .…”

“…The diffraction patterns are consistent with the monoclinic phase of TiNb 24 O 62 as reported from the previous literature with no impure phases such as Nb 2 O 5 and other titanium niobium oxides. 22,[38][39][40] The wrapping of rGO over TNO x does not alter the crystal structure of TiNb 24 O 62 and the additional peak positioned at 26.5 • in TNO x /rGO corresponds to the (0 0 2) graphitic plane of rGO. 41,42 The structure of TNO was also confirmed by Raman spectra (Figure 1D).…”

“…The blocks are interconnected to form a shear plane by edge sharing octahedra and tetrahedra units (Figure 1A). 18,19 Due to these features, titanium niobium oxides have been demonstrated to be high‐rate and low volume expansion (6%–17%) anode materials for Li‐ion battery 19–24 . Considering the benefits of tunnel structure and the three‐electron redox process of Ti 4+ to Ti 3+ and Nb 5+ to Nb 3+ , titanium niobium oxides could be considered potential anode materials for SIBs and PIBs, but unfortunately only one titanium niobium oxide, TiNb 2 O 7 , has been reported for SIBs so far.…”

“…18,19 Due to these features, titanium niobium oxides have been demonstrated to be high-rate and low volume expansion (6%-17%) anode materials for Li-ion battery. [19][20][21][22][23][24] Considering the benefits of tunnel structure and the three-electron redox process of Ti 4+ to Ti 3+ and Nb 5+ to Nb 3+ , titanium niobium oxides could be considered potential anode materials for SIBs and PIBs, but unfortunately only one titanium niobium oxide, TiNb 2 O 7 , has been reported for SIBs so far. Huang et al investigated the Na + storage performance of the amorphous TiNb 2 O 7 phase synthesized by ball milling.…”

“Fast-Charging” Anode Materials for Lithium-Ion Batteries from Perspective of Ion Diffusion in Crystal Structure

“…TiNbO possesses diverse compositions and structures, the general formula is TiNb x O 2+2.5 x , including TiNb 2 O 7 , Ti 2 Nb 2 O 9 , Ti 2 Nb 10 O 29 , TiNb 24 O 62 , TiNb 38 O 97 , and TiNb 52 O 132 , etc. , The theoretical specific capacity of the TiNb x O 2+2.5 x materials can be obtained by adopting eq : C = 403 − 5441 / ( 133 x + 80 ) …”