Porous Anatase-TiO2(B) Dual-Phase Nanorods Prepared from in Situ Pyrolysis of a Single Molecule Precursor Offer High Performance Lithium-Ion Storage.

Abstract

To overcome the problems faced by TiO2 materials for lithium-ion batteries usage, such as easy nanoparticles agglomeration during cycling and poor cycling performance, in this study, TiO2 nanorods with the controlled phase compositions are prepared via direct pyrolysis of single molecule precursors in combination with a simple washing process. By tuning the external cations in the single source precursors, three TiO2 samples in a nanorod shape with the compositions of pure anatase, anatase-rutile dual phase, and anatase-TiO2(B) dual phase are synthesized successfully. High-resolution transmission electron microscopy, X-ray powder diffraction, and Raman measurements confirm the phase structures and compositions of the three prepared samples. The electrochemical results manifest that all the three nanorod-shaped TiO2 samples show the long-term cycling stability as negative materials for LIBs. Among them, the TiO2 sample with the combination of the anatase and TiO2-B phase shows the best performance, with the specific capacity of ∼184, 164, 140, 105, 80, and 60 mAh g-1 at 0.1, 0.3, 0.5, 1.5, 3.0, and 5.0 A g-1, respectively, and showing no capacity loss and low resistance after 1000 cycles at 1.5 A g-1. By the analysis of the cyclic voltammetry results recorded from different scan rates, the lithium-ion storage mechanism is clarified, which is dominated by the semi-infinite linear diffusion (anatase phase) in combination with the partial surface pseudocapacitive contribution [TiO2(B) phase]. As a result, this sample shows a great potential as a negative material for LIBs because of its electrochemical stability, high specific capacity, and superior rate capability. The proof-of-concept design of the anatase and TiO2-B dual phase may provide a new strategy for the synthesis of high performance TiO2-based anode material for LIBs.