Two-dimensional sandwich-like heterostructures of amorphous VOx/MXene as freestanding cathode materials with superior electrochemical performance for aqueous zinc-ion batteries

Although vanadium-based compounds are considered to be reliable zinc storage materials due to their high theoretical specific capacity, notorious poor conductivity and unstable structure hamper their practical applications. Herein, novel two-dimensional (2D) sandwich-like heterostructures of amorphous vanadium dioxide uniformly grown on two sides of ultrathin MXene nanosheets (A-VOx/M heterostructures) are constructed by ion adsorption method and following low-temperature annealing, which can be readily incorporated into carbon nanotube (CNT) network to obtain freestanding cathodes for aqueous zinc-ion batteries. The combination of 2D heterostructure, amorphous framework and conductive substrate endows A-VOx/M heterostructures with short ion diffusion pathway, high chemical stability, extra active sites and superior electrical conductivity. The freestanding A-VOx/M heterostructured cathodes for aqueous zinc-ion batteries exhibit a remarkable discharge capacity of 362 mAh g(-1) at 0.2 A g(-1) and high-rate capability of 202 mAh g(-1) at 15 A g(-1) as well as admirable cycling stability with a capacity decay of only 0.0043% per cycle over 3000 cycles. Besides, due to the outstanding conductivity and stability of freestanding A-VOx/M heterostructured cathodes, soft-package batteries are assembled with steady electrochemical performance, suggesting brilliant future in the field of energy storage.

Automated summary

Novel 2D sandwich-like heterostructures of amorphous vanadium dioxide grown on MXene nanosheets are used as freestanding cathodes for aqueous zinc-ion batteries. These cathodes exhibit high capacity, rate capability, and cycling stability due to their unique structure and conductivity. They also show potential for applications in energy storage.