Ultrathin 2D Mesoporous TiO₂/rGO Heterostructure for High‐Performance Lithium Storage

Abstract

Lithium‐ion batteries (LIBs) have been widely applied and studied as an effective energy supplement for a variety of electronic devices. Titanium dioxide (TiO2), with a high theoretical capacity (335 mAh g−1) and low volume expansion ratio upon lithiation, has been considered as one of the most promising anode materials for LIBs. However, the application of TiO2 is hindered by its low electrical conductivity and slow ionic diffusion rate. Herein, a 2D ultrathin mesoporous TiO2/reduced graphene (rGO) heterostructure is fabricated via a layer‐by‐layer assembly process. The synergistic effect of ultrathin mesoporous TiO2 and the rGO nanosheets significantly enhances the ionic diffusion and electron conductivity of the composite. The introduced 2D mesoporous heterostructure delivers a significantly improved capacity of 350 mAh g−1 at a current density of 200 mA g−1 and excellent cycling stability, with a capacity of 245 mAh g−1 maintained over 1000 cycles at a high current density of 1 A g−1. The in situ transmission electron microscopy analysis indicates that the volume of the as‐prepared 2D heterostructures changes slightly upon the insertion and extraction of Li+, thus contributing to the enhanced long‐cycle performance.

Immobilizing Polysulfide by In Situ Topochemical Oxidation Derivative TiC@Carbon‐Included TiO2 Core–Shell Sulfur Hosts for Advanced Lithium–Sulfur Batteries

“…As shown in Figure 3a, the TiC@C‐TiO 2 composite exhibits a sharp Raman scattering peak at 154 cm −1 , corresponding to the E g 1 mode of anatase TiO 2 . [ 41,42 ] Other Raman scattering peaks are assigned to the E g 2 , B 1g 1 , B 1g 2 + A 1g , and E g 3 vibrational modes of anatase TiO 2 , [ 41,43 ] respectively. In addition, two characteristic D band (1343 cm −1 ) and G band (1602 cm −1 ) of carbon can be identified in the TiC@C‐TiO 2 sample (Figure 3b), [ 44 ] proving the existence of amorphous carbon within the C‐TiO 2 shell.…”

“…Figure S4 in the Supporting Information shows the Raman spectra of the TiC and p‐TiO 2 samples. The TiC sample shows three Raman scattering peaks at 257, 409, and 604 cm −1 , [ 45 ] respectively, while the p‐TiO 2 samples exhibit five Raman scattering peaks at 145, 199, 397, 517, and 638 cm −1 , corresponding to the E g 1 , E g 2 , B 1g 1 , B 1g 2 + A 1g , and E g 3 vibrational modes of anatase TiO 2 , [ 41–43 ] respectively. By comparison with the Raman spectrum of the TiC@C‐TiO 2 composite, it is found that both the TiC and p‐TiO 2 samples have no characteristic D band and G band of carbon, indicating the absence of amorphous carbon in these samples.…”

“…2 + A 1g , and E g 3 vibrational modes of anatase TiO 2 , [41][42][43] respectively. By comparison with the Raman spectrum of the TiC@C-TiO 2 composite, it is found that both the TiC and p-TiO 2 samples have no characteristic D band and G band of carbon, indicating the absence of amorphous carbon in these samples.…”

“…As shown in Figure 3a, the TiC@C-TiO 2 composite exhibits a sharp Raman scattering peak at 154 cm −1 , corresponding to the E g 1 mode of anatase TiO 2 . [41,42] Other Raman scattering peaks are assigned to the E g 2 , B 1g…”

Nanostructured Graphene Oxide-Based Hybrids as Anodes for Lithium-Ion Batteries

“…The hierarchically porous TiO 2 /rGO hybrid anode material designed by Yu and coworkers [352] exhibited a reversible capacity of 250 mAh g −1 at 1C rate (1 C = 335 mA g −1 ) in the voltage range of 1.0-3.0 V. After 1000 cycles, stable capacities of 176 and 160 mAh g −1 were delivered at 5C and 500 cycles at 10C, respectively. An ultrathin mesoporous TiO 2 /rGO composite was obtained by Liang et al via a layer-by-layer process [353]. Several studies were attempted to enhance the performance of TiO 2 /rGO composites by doping with nitrogen.…”