High-Temperature Stable Anatase Titanium Oxide Nanofibers for Lithium-Ion Battery Anodes

Control of the crystal structure of electrochemically active materials is an important approach to fabricating high-performance electrodes for lithium-ion batteries (LIBs). Here, we report a methodology for controlling the crystal structure of TiO₂ nanofibers by adding aluminum isopropoxide to a common sol-gel precursor solution utilized to create TiO₂ nanofibers. The introduction of aluminum cations impedes the phase transformation of electrospun TiO₂ nanofibers from the anatase to the rutile phase, which inevitably occurs in the typical annealing process utilized for the formation of TiO₂ crystals. As a result, high-temperature stable anatase TiO₂ nanofibers were created in which the crystal structure was well-maintained even at high annealing temperatures of up to 700 °C. Finally, the resulting anatase TiO₂ nanofibers were utilized to prepare LIB anodes, and their electrochemical performance was compared to pristine TiO₂ nanofibers that contain both anatase and rutile phases. Compared to the electrode prepared with pristine TiO₂ nanofibers, the electrode prepared with anatase TiO₂ nanofibers exhibited excellent electrochemical performances such as an initial Coulombic efficiency of 83.9%, a capacity retention of 89.5% after 100 cycles, and a rate capability of 48.5% at a current density of 10 C (1 C = 200 mA g^-1).