TiO₂ bunchy hierarchical structure with effective enhancement in sodium storage behaviors

Abstract Bronze phase TiO₂ [TiO₂(B)] has great research potential for sodium storage since it has a higher theoretical capacity and ion mobility compared with other phases of TiO₂. In this case, preparing porous TiO₂(B) nanosheets, which can provide abundant sodium insertion channels, is the most effective way to improve transport kinetics. Here, we use the strong one‐dimensional TiO₂ nanowires as the matrix for stringing these nanosheets together through a simple solvothermal method to build a bunchy hierarchical structure [TiO₂(B)‐BH], which has fast pseudocapacitance behavior, high structural stability, and effective ion/electron transport. With the superiorities of this structure design, TiO₂(B)‐BH has a higher capacity (131 vs. 70 mAh g⁻¹ [TiO₂‐NWs] at 0.5 C). And it is worth mentioning that the reversible capacity of up to 500 cycles can still be maintained at 85 mAh g⁻¹ at a high rate of 10 C. Meanwhile, we also further analyzed the sodium storage mechanism through the ex‐situ X‐ray powder diffraction test, which proved the high structural stability of TiO₂(B)‐BH in the process of sodiumization/de‐sodiumization. This strategy of uniformly integrating nanosheets into a matrix can also be extended to preparing electrode material structures of other energy devices.