1D Sub-Nanotubes with Anatase/Bronze TiO 2 Nanocrystal Wall for High-Rate and Long-Life Sodium-Ion Batteries.

The development of 1D nanostructures with enhanced material properties has been an attractive endeavor for applications in energy and environmental fields, but it remains a major research challenge. Herein, this work demonstrates a simple, gel-derived method to synthesize uniform 1D elongated sub-nanotubes with an anatase/bronze TiO ₂ nanocrystal wall (TiO ₂ SNTs). The transformation mechanism of TiO ₂ SNTs is studied by various ex situ characterization techniques. The resulting 1D nanostructures exhibit, synchronously, a high aspect ratio, open tubular interior, and anatase/bronze nanocrystal TiO ₂ wall. This results in excellent properties of electron/ion transport and reaction kinetics. Consequently, as an anode material for sodium-ion batteries (SIBs), the TiO ₂ SNTs display an ultrastable long-life cycling stability with a capacity of 107 mAh g ^-1 at 16 C after 4000 cycles and a high-rate capacity of 94 mAh g ^-1 at 32 C. This a high-rate and long-life performance is superior to any report on pure TiO ₂ for SIBs. This work provides new fundamental information for the design and fabrication of inorganic structures for energy and environmental applications.
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