Interwoven scaffolded porous titanium oxide nanocubes/carbon nanotubes framework for high-performance sodium-ion battery

Supercapacitor-like Na-ion batteries have attracted much attention due to the high energy density of batteries and power density of capacitors. Titanium dioxide (TiO₂), is a promising anode material. Its performance is however seriously hindered by its low electrical conductivity and the sluggish diffusion of sodium ions (Na⁺) in the TiO₂ matrix. Herein, this work combines porous TiO₂ nanocubes with carbon nanotubes (CNTs) to enhance the electrical conductivity and accelerate Na⁺ diffusivity for Na-ion batteries (NIBs). In this composite, an interwoven scaffolded TiO₂/CNTs framework is formed to provide abundant channels and shorter diffusion pathways for electrons and ions. The in-situ X-ray diffraction and cyclic voltammetry confirm the low strain and superior transport kinetics in Na⁺ intercalation/extraction processes. In addition, the chemically bonded TiO₂/CNTs hybrid provides a more feasible channel for Na⁺ insertion/extraction with a much lower energy barrier. Consequently, the TiO₂/CNTs composite exhibits excellent electrochemical performance with a capacity of 223.4 mAh g⁻¹ at 1 C and a capacity of 142.8 mAh g⁻¹ at 10 C (3.35 A g⁻¹). The work here reveals that the combination of active materials with CNTs can largely improve the utilization efficiency and enhance their sodium storage.