Ultrahigh capacity and cyclability of dual-phase TiO2 nanowires with low working potential at room and subzero temperatures

The commercialization of TiO2 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 TiO2 nanowires composed of anatase and TiO2–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 TiO2-350, 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, TiO2-350 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 TiO2. Cyclic voltammetry results indicated that the ultrahigh capacity of the TiO2 nanowire is the main reason that the capacitive contribution is below 1.0 V. Structural analyses indicated the solid solution reaction of TiO2-350 nanowires with Li+ and the excellent structure stability during cycling, which contributes to the excellent cyclic performance of nanowires. Furthermore, the TiO2-350 anode exhibits superb low-temperature performance between 0.01 V and 3.0 V at 273 K and 248 K. This work demonstrates a TiO2-based anode with ultrahigh capacity and low working potential, and will promote the practical application of TiO2-based materials for all-climate LIB anodes.