Enhanced Zn2+ transfer dynamics via a 3D bird nest-like VO2/MXene heterojunction for ultrahigh-rate aqueous zinc-ion batteries

With the increasing demand of the large-scale storage equipment, more scholars are involved in the research of aqueous zinc-ion batteries (AZIBs) owing to their cost-effectiveness, good safety and environment-friendly. Herein, we demonstrate a three-dimensional (3D) bird nest-like VO2/MXene heterojunction using a facile ultrasonication method combined with freeze-drying. The particular heterostructure of cathode material not only effectively suppresses the volume changes of electrodes, but also prominently improves the kinetics of active materials upon cycling, thus results in remarkably enhanced electrochemical performance. It delivers a specific capacity of 445 mAh g−1 at 0.1 A g−1 and exhibits unexceptionable high-rate capacities of 244.5 and 225.0 mAh g−1 at 20.0 (over 2600 cycles) and 30.0 (over 4000 cycles) A g−1, respectively. Moreover, a high specific capacity of 247.2 mAh g−1 is achieved at 5.0 A g−1 at −20 °C, and almost no capacity loss is observed even after 2500 cycles. Moreover, the further research on ex-situ XPS and XRD measurements are carried out for VO2/MXene material in hope of better understanding its Zn2+ storage mechanism. The proposed interfacial engineering approach combining metal oxides and MXene in this work opens up a novel way for cathode in AZIBs.