TiO2 nanotubes with different spacing, Fe2O3 decoration and their evaluation for Li-ion battery application

摘要

In the present work, we report on the use of organized TiO2 nanotube (NT) layers with a regular intertube spacing for the growth of highly defined alpha-Fe2O3 nano-needles in the interspace. These alpha-Fe2O3 decorated TiO2 NTs are then explored for Li-ion battery applications and compared to classic close-packed (CP) NTs that are decorated with various amounts of nanoscale alpha-Fe2O3. We show that NTs with tube-to-tube spacing allow uniform decoration of individual NTs with regular arrangements of hematite nano-needles. The tube spacing also facilitates the electrolyte penetration as well as yielding better ion diffusion. While bare CP NTs show a higher capacitance of 71 mu Ah cm(-2) compared to bare spaced NTs with a capacitance of 54 mu Ah cm(-2), the hierarchical decoration with secondary metal oxide, alpha-Fe2O3, remarkably enhances the Li-ion battery performance. Namely, spaced NTs with alpha-Fe2O3 decoration have an areal capacitance of 477 mu Ah cm(-2), i.e. they have nearly similar to 8 times higher capacitance. However, the areal capacitance of CP NTs with alpha-Fe2O3 decoration saturates at 208 mu Ah cm(-2), i.e. is limited to similar to 3 times increase.