One-dimensional nanofiber architecture of an anatase TiO2–carbon composite with improved sodium storage performance

Abstract

Titanium-based oxides have been considered promising anode materials for rechargeable sodium (Na)-ion batteries (NIBs); however, the slow reaction kinetics of TiO₂ due to its low electrical conductivity remains a critical problem to be addressed for its practical application in NIBs. Here, we report one-dimensional (1D) TiO₂–C composite nanofibers for use as an anode for NIBs, which were fabricated via an electrospinning technique combined with optimized heat-treatment. The TiO₂–C composite nanofibers are composed of tiny anatase TiO₂ nanocrystals surrounded by and/or embedded in the conducting carbon matrix. When tested in an electrochemical Na cell, the TiO₂–C nanofiber electrode retained a high charge capacity of 140 mA h g⁻¹, even after 100 cycles at a current density of 60 mA g⁻¹, and it exhibited excellent rate-capability (105 mA h g⁻¹ at 3 A g⁻¹), proving its feasibility as an NIB anode. The superior Na storage performance of the nanofiber anode is mainly attributed to the unique composite architecture, that is, a large number of active sites per volume due to the high aspect ratios and short lengths for Na transport through 1D nanofibers and TiO₂ nanocrystals as well as highly conducting electron paths.