Dual-cation preintercalated and amorphous carbon confined vanadium oxides as a superior cathode for aqueous zinc-ion batteries

Rechargeable aqueous zinc-ion batteries (AZIBs) that directly use metallic zinc as anode and mildly acidic Zn2+-containing aqueous solutions as electrolytes have exhibited promising complementarity for well-established lithium-ion batteries. The fabrication of high-voltage, high-capacity, and durable cathode and stable anode are the burning issues of fabricating high-performance AZIBs. Herein, the small amount of dual-cation preintercalated and amorphous carbon confined vanadium dioxide (Ni0.006Ca0.0045VO2@C) was prepared for high-performance Zn2+-storage materials, and subsequent in situ electrochemical anodic oxidation strategy was used to convert Ni0.006Ca0.0045VO2@C to δ-(Ni,Ca)V2O5@C as high-capacity AZIB cathode. The elaborate architecture not only showed a high specific capacity of 433.8 mAh g−1 at 0.1 A g−1 but also retained a reversible capacity of 74 mAh g−1 after 4000 cycles at 5 A g−1. In addition, the Zn2+/H+ co-intercalation mechanism was also verified by employing ex situ XRD and ex situ XPS. Finally, the flexible quasi-solid-state ZIBs were also assembled with the Ni0.006Ca0.0045VO2@C as cathode and polyvinyl alcohol hydrogel as electrolyte, suggesting its promising application for the superior Zn2+-storage performance.