In situ preparation of an anatase/rutile-TiO(2)/Ti(3)C(2)T(x) hybrid electrode for durable sodium ion batteries

Herein, a facile one-step method is developed to in situ prepare crystalline anatase and rutile TiO(2) nanocrystals on Ti(3)C(2)T(x) by regulating the metastable Ti ions. The combination of TiO(2) nanocrystals and Ti(3)C(2)T(x) not only introduces extensive accessible sites for Na(+) storage, but also promotes the charge transport by efficiently relieving the collapse of Ti(3)C(2)T(x). Compared with pristine Ti(3)C(2)T(x), the optimized TiO(2)/Ti(3)C(2)T(x) hybrid electrode (anatase/rutile-TiO(2)/Ti(3)C(2)T(x), A/R-TiO(2)/Ti(3)C(2)T(x)) exhibits a desirable specific surface area (22.5 m(2) g(−1)), an ultralow charge transfer resistance (42.46 Ω) and excellent ion diffusion (4.01 × 10(−14)). Remarkably, rich oxygen vacancies are produced on TiO(2)/Ti(3)C(2)T(x) which is beneficial to enhance the insertion/de-insertion of Na(+) during the charge/discharge process. As a result, the A/R-TiO(2)/Ti(3)C(2)T(x) delivers a high average capacity of 205.4 mA h g(−1) at 100 mA g(−1) and a desirable capacitance retention rate of 84.7% can be achieved after 600 cycles at 500 mA g(−1).