Ultrahigh capacity and cyclability of dual-phase TiO nanowires with low working potential at room and subzero temperatures

The commercialization of TiO 2 materials for lithium-ion battery (LIB) anodes has been seriously limited due to unsatisfactory capacities and high voltage plateaus vs. Li/Li + (∼1.75 V). In this work, we synthesized unique dual-phase TiO 2 nanowires composed of anatase and TiO 2 -B phases with tunable phase ratios and studied their electrochemical performance in the extended potential range of 0.01-3.0 V. It was found that the dual-phase nanowire with a phase ratio of ∼1.0, named TiO 2 -350, possesses the best rate and cyclic performance. More importantly, lowering the discharge cut-off voltage from 1.0 V to 0.01 V significantly increases the capacities, and moreover results in a decreased average discharge voltage of ∼0.58 V vs. Li/Li + . At the rates of 0.5C and 1C, TiO 2 -350 delivers the ultrahigh capacities of 518.0 and 444.5 mA h g −1 and remarkable long-term cyclic stability, which are strikingly higher than those reported in the literature and the theoretical capacity of TiO 2 . Cyclic voltammetry results indicated that the ultrahigh capacity of the TiO 2 nanowire is the main reason that the capacitive contribution is below 1.0 V. Structural analyses indicated the solid solution reaction of TiO 2 -350 nanowires with Li + and the excellent structure stability during cycling, which contributes to the excellent cyclic performance of nanowires. Furthermore, the TiO 2 -350 anode exhibits superb low-temperature performance between 0.01 V and 3.0 V at 273 K and 248 K. This work demonstrates a TiO 2 -based anode with ultrahigh capacity and low working potential, and will promote the practical application of TiO 2 -based materials for all-climate LIB anodes. Dual-phase TiO 2 nanowires exhibit ultrahigh reversible capacity and excellent long-term cycling stability with low working potential at room and subzero temperatures.