Controlled Growth and Ion Intercalation Mechanism of Monocrystalline Niobium Pentoxide Nanotubes for Advanced Rechargeable Aluminum-Ion Batteries

Rechargeable aluminum-ion batteries (RAIBs) have attracted rising attention owing to the high theoretical volumetric capacity, rich resource abundance, and good safety performance. However, the existing RAIB systems usually exhibit relatively low specific capacities limited by the cathode materials. In this study, we developed a one-step chemical vapor deposition method to prepare single-crystal orthogonal Nb2O5 nanotubes for serving as high-performance electrode material for RAIBs, showing a high reversible capability of 556 mA h g-1 at 25 mA g-1 and good thermal endurability at elevated temperature (50 °C). The combination of a series of detailed ex-situ structural characterizations verified the reversible intercalation/de-intercalation of chloroaluminate anions (AlCl4-) into/from the (001) planes of monocrystalline Nb2O5 nanotubes. It also revealed that the nanoarchitecture of Nb2O5 nanotubes with thin tube walls, hollow inner space and short ion transport distance is conducive to the rapid kinetics of insertion/extraction process. This work provides a promising route to design high-performance electrode materials based on transition-metal compounds for RAIBs via the rationally modulation of structure and morphology.