Nanobelt-like vanadium dioxide with three-dimensional interconnected tunnel structure enables ultrafast Al-ion storage

Aqueous aluminum-based batteries (AABs) are one of promising energy storage systems because of its high safety and high capacity of aluminum. However, the capacity and cycling performance are limited by the unstable structure of cathode materials, which hinder the further applications of AABs. Here, we develop nanobelt-like vanadium dioxide (VO2) with three-dimensional interconnected tunnel structure as fast Al3+ storage cathode for AABs. The VO2 electrode can deliver a high capacity of 235 mAh g−1 at the current density of 200 mA g−1 as well as a good rate ability of 49.3% capacity retention as the current density increases to 2 A g−1. Moreover, ex situ characterizations further confirm the Al3+ ion intercalation/deintercalation mechanism in VO2 during the charge/discharge process. Our work provides new design principle for improving cathode performance in AABs.