In situ electrochemically activated V 2 O 3 @MXene cathode for a super high-rate and long-life Zn-ion battery.

The development of a high specific capacity and stable vanadium-based cathode material is very attractive for aqueous zinc-ion batteries (ZIBs). Herein, an in situ electrochemically oxidized cathode is fabricated based on a V 2 O 3 @MXene cathode for Zn-ion storage. V 2 O 3 @MXene undergoes a phase transition to Zn 3 (OH) 2 V 2 O 7 ·2H 2 O and Zn y VO z on the first charge, thus allowing for the subsequent insertion/de-insertion of zinc ions, which can be regulated by the amount of H 2 O in the electrolyte. The MXene in the composite was also beneficial to electron transfer and cycling stability. V 2 O 3 @MXene delivered a high capacity of 450 mA h g -1 at 0.2 A g -1 , ultra-high-rate performance and cycling stability as well as high energy density.