Phases Hybriding and Hierarchical Structuring of Mesoporous TiO₂ Nanowire Bundles for High‐Rate and High‐Capacity Lithium Batteries

Abstract

A hierarchical mesoporous TiO2 nanowire bundles (HM‐TiO2‐NB) superstructure with amorphous surface and straight nanochannels has been designed and synthesized through a templating method at a low temperature under acidic and wet conditions. The obtained HM‐TiO2‐NB superstructure demonstrates high reversible capacity, excellent cycling performance, and superior rate capability. Most importantly, a self‐improving phenomenon of Li+ insertion capability based on two simultaneous effects, the crystallization of amorphous TiO2 and the formation of Li2Ti2O4 crystalline dots on the surface of TiO2 nanowires, has been clearly revealed through ex situ transmission electron microcopy (TEM), high‐resolution transmission electron microscopy (HRTEM), X‐ray diffraction (XRD), Raman, and X‐ray photoelectron spectroscopy (XPS) techniques during the Li+ insertion process. When discharged for 100 cycles at 1 C, the HM‐TiO2‐NB exhibits a reversible capacity of 174 mA h g−1. Even when the current density is increased to 50 C, a very stable and extraordinarily high reversible capacity of 96 mA h g−1 can be delivered after 50 cycles. Compared to the previously reported results, both the lithium storage capacity and rate capability of our pure TiO2 material without any additives are among the highest values reported. The advanced electrochemical performance of these HM‐TiO2‐NB superstructures is the result of the synergistic effect of hybriding of amorphous and crystalline (anatase/rutile) phases and hierarchically structuring of TiO2 nanowire bundles. Our material could be a very promising anodic material for lithium‐ion batteries.

Hierarchical TiO2/C nanocomposite monoliths with a robust scaffolding architecture, mesopore–macropore network and TiO2–C heterostructure for high-performance lithium ion batteries

“…TiO 2 /C-500 retains 47.9 % of capacity at 5 C, which is higher than reported anode materials based on hierarchically structured TiO 2 . 16,32 Reducing the current rate to 0.2 C results in a discharge capacity of 179 mA h g -1…”

Eco-friendly synthesis of rutile TiO2 nanostructures with controlled morphology for efficient lithium-ion batteries

“…Particularly, it should be noted that the acidic condition provided by a certain amount of HCl plays a key role for effectively controlling the hydrolysis rate of TiOSO 4 during the process. [31] Without addition of HCl, we can only obtain the TiO 2 nanoparticles as shown in SEM images and the corresponding EDX patterns of the samples are displayed in Fig. 2.…”

Layer‐by‐Layer Synthesis of Thick Mesoporous TiO2 Films with Vertically Oriented Accessible Nanopores and Their Application for Lithium‐Ion Battery Negative Electrodes

“…[1a] Among them, the use of porous TiO 2 has been proven to be effective for the improvement in kinetics of lithium‐ion (Li + ) insertion/extraction since the pore structure provides materials with rapid ion transport paths and a large surface area for charge transfer reactions. [5a,9] Also, it has been found that a mesoporous nanowire bundle structure could decrease the polarization and enhance performance at high rates . Modification of the material composition by doping or introduction of carbon has also been shown to enhance electrical conductivity, and thus high‐rate LIB performance, but here the focus will be on enhancing the performance of the nanoporous TiO 2 platform itself.…”