Carbon Nanolayer-Wrapped Mesoporous TiO₂–B/Anatase for Li⁺ Storage

Abstract

Optimizing the microstructure, the chemical composition, the surface-wrapped carbon nanolayer, and oxygen vacancies is expected to be an effective strategy for ameliorating electrochemical performance of anode materials. In this work, a series of mesoporous TiO 2 with different phase compositions and carbon nanolayers have been rationally designed and constructed. The in situ-synthesized carbon nanolayer could not only lead to the enhanced electric conductivity but also promote the content and stability of TiO 2 −B in the TiO 2 −B/anatase mixed phases. Moreover, mesoporous TiO 2 composites consisting of different ratios of TiO 2 −B/anatase with desired interfaces can be obtained by tailoring the carbonization temperature. As a result, the carbon nanolayer-coated mesoporous TiO 2 with the dual phase obtained at 600 °C (TiO 2 −B/anatase@C-6) not only achieves a high specific capacity (473.5 mA h g −1 at 0.1 A g −1 ) and a superior rate performance (181.9 mA h g −1 at a high current density of 5 A g −1 ) but also displays a long cycling lifetime by retaining 134% of its initial capacity after 1000 cycles at 1.0 A g −1 . The boosted electrochemical properties are owing to synergistic effects of the unique dual phase (TiO 2 −B/anatase) with an optimized mass ratio, the rich defects in the anatase/TiO 2 −B interface, the mesoporous structure, and the surface-wrapped highly conductive carbon layer. This work demonstrates an innovative approach to construct mesoporous TiO 2 nanocomposites with superior Li + storage performance.

One‐pot hydrothermal synthesis of porous anatase TiO2 nanotube formed bundles for lithium ion battery anodes

“…[ 21,22 ] The curve in the high‐resolution spectrum of O 1s shown in Figure 4c could be deconvoluted into three peaks at around 529.8, 530.4, and 531.7 eV, which are related to Ti−O, oxygen vacancies, and absorbed water in TiO 2 , respectively. [ 20 ]…”

“…[19] Figure 4b shows the Ti2p XPS spectrum, which can be divided into four peaks at 458.2, 458.9, 463.7, and 646.6 eV, corresponding to Ti 3+ 2p 3/2 , Ti 4+ 2p 3/2 , Ti 3+ 2p 1/2 , and Ti 4+ 2p 1/2 , respectively. [20] The existence of Ti 3+ could be ascribed to the introduction of oxygen vacancies generated in the annealing process at 400 C, which can promote Li-ion diffusion and reduce the charge transfer resistance, beneficial for improving the electrochemical performances in LIBs. [21,22] The curve in the high-resolution spectrum of O 1s shown in Figure 4c could be deconvoluted into three peaks at around 529.8, 530.4, and 531.7 eV, which are related to TiÀO, oxygen vacancies, and absorbed water in TiO 2 , respectively.…”

Defect‐rich bronze titanium dioxide ultrathin nanosheets supported on carbon nanotubes for enhanced lithium‐ion storages

“…The EIS of electrodes at 0.5 A g −1 were tested from high frequency (10 kHz) to low frequency (100 mHz) before and after 50 cycles. The Nyquist plots of the TiO 2 (B)‐CNTs electrode before and after cycling (Figure 6A) presented smaller semicircles and larger straight slope in different frequency region than that of pure TiO 2 (B) electrode, suggesting the accelerated electron transfer and lithium‐ion diffusions in TiO 2 (B)‐CNTs electrode 7,49 . The coefficient of lithium‐ion diffusion (D Li + ) for these electrodes after cycling can be calculated using Equation () 50 : …”

“…Compared with the common TiO 2 crystal phase, such as anatase and rutile, TiO 2 (B) (TiO 2 Bronze phase) is more conducive to Li + intercalation because of its open crystal structure 3‐6 . This structure is made up of three TiO 6 units, which share three corners and edges to form open channels 7 . TiO 2 (B) unique structure enables it to effectively alleviate volume expansion during the discharge/charge processes 8 .…”

“…[3][4][5][6] This structure is made up of three TiO 6 units, which share three corners and edges to form open channels. 7 TiO 2 (B) unique structure enables it to effectively alleviate volume expansion during the discharge/charge processes. 8 Besides, this special structure combined with the pseudocapacitance effect makes the theoretical specific capacity of TiO 2 (B) as anodes in LIBs is twice that of anatase and rutile TiO 2.…”