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

Vanadium dioxide (VO2) 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 VO2 results in an unsatisfactory electrochemical performance. Herein, a flower-like VO2/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 VO2/CNTs cathode exhibits a high reversible capacity (410 mAh<middle dot>g(-1)), superior rate performance (305 mAh<middle dot>g(-1) at 5 A<middle dot>g(-1)), and excellent cycling stability (a reversible capacity of 221 mAh<middle dot>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.