Brookite phase vanadium dioxide (B) with nanosheet structure for superior rate capability aqueous Zn-ion batteries

Abstract

• We prepared VO 2 (B) nanoflakes with petal-shaped folds as a new cathode material. • The VO 2 (B) had higher activity and quicker electron transfer kinetics. • The cathode material got high capacity and excellent rate performance. • The VO 2 (B) obtained for 101.4% high capacity retention at 10 A g −1 after 2000 cycles. Vanadium dioxide is widely used as a low-cost, high-safety cathode material for aqueous zinc ion batteries because of its tunnel structure that facilitates the intercalates/de-intercalates of Zn 2+ . However, it has been a challenge to improve the rate performance of vanadium dioxide and its cycling stability at high current densities. Here, we report VO 2 (B) nanoflakes with petal-shaped folds at the top. Combine with a higher pseudocapacitance contribution and part of diffusion control, the VO 2 (B) led to higher electrochemical activity, quicker electron transfer kinetics and better electronic conductivity. The VO 2 (B) discovers a considerable capacity of 301.7 mA h g −1 at 1 A g −1 , an impressive rate performance of 248.4 mA h g −1 after 1000 cycles at 5 A g −1 ,and 89.0 mA h g −1 at the current density of 50 A g −1 . More surprisingly, the VO 2 (B) can keep 201.3 mA h g −1 after 2000 cycles at 10 A g −1 , and obtain 101.4% high capacity retention. This method effectively improves the rate performance and long-cycle stability of vanadium dioxide, and also provides ideas for improving the performance of other cathode materials for aqueous zinc ion batteries.