In situ preparation of an anatase/rutile-TiO₂/Ti₃C₂T hybrid electrode for durable sodium ion batteries

Herein, a facile one-step method is developed to in situ prepare crystalline anatase and rutile TiO₂ nanocrystals on Ti₃C₂T by regulating the metastable Ti ions. The combination of TiO₂ nanocrystals and Ti₃C₂T not only introduces extensive accessible sites for Na⁺ storage, but also promotes the charge transport by efficiently relieving the collapse of Ti₃C₂T . Compared with pristine Ti₃C₂T , the optimized TiO₂/Ti₃C₂T hybrid electrode (anatase/rutile-TiO₂/Ti₃C₂T , A/R-TiO₂/Ti₃C₂T ) exhibits a desirable specific surface area (22.5 m² 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 TiO₂/Ti₃C₂T which is beneficial to enhance the insertion/de-insertion of Na⁺ during the charge/discharge process. As a result, the A/R-TiO₂/Ti₃C₂T 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.