Boosting the zinc storage performance of vanadium dioxide by integrated morphology engineering and carbon nanotube conductive networks

Vanadium dioxide (VO 2 ) with the advantages of high theoretical capacity and tunnel structure has attracted considerable promising candidates for aqueous zinc-ion batteries. Nevertheless, the intrinsic low electronic conductivity of VO 2 results in an unsatisfactory electrochemical performance. Herein, a flower-like VO 2 /carbon nanotubes (CNTs) composite was obtained by a facile hydrothermal method. The unique flower-like morphology shortens the ion transport length and facilitates electrolyte infiltration. Meanwhile, the CNT conductive networks is in favor of fast electron transfer. A highly reversible zinc storage mechanism was revealed by ex-situ X-ray diffraction and X-ray photoelectron spectroscopy. As a result, the VO 2 /CNTs cathode exhibits a high reversible capacity (410 mAh·g −1 ), superior rate performance (305 mAh·g −1 at 5 A·g −1 ), and excellent cycling stability (a reversible capacity of 221 mAh·g −1 was maintained even after 2000 cycles). This work provides a guide for the design of high-performance cathode materials for aqueous zinc metal batteries.