Porous Anatase-TiO₂(B) Dual-Phase Nanorods Prepared from <i>in Situ</i> 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.