Oxygen-Deficient HNaV6O16•4H2O@Reduced Graphene Oxide as a Cathode for Aqueous Rechargeable Zinc-Ion Batteries

Aqueous zinc ion batteries (AZIBs) are considered as grid energy storage materials due to their high abundance, low cost, safety, pollution-free characteristic. However, its poor conductivity and insufficient structural stability are still the key factors restricting the development of cathode materials. Therefore, we adopt a one-step hydrothermal method to construct HNaV6O16 center dot 4H(2)O@reduced graphene oxide with oxygen-rich defects and large Zn2+ deintercalation channels of 10.87 angstrom (O-d-HNaVO@rGO). Encouragingly, our constructed oxygen-deficient Zn//Od-HNaVO@rGO battery possesses 380.4 mA h g(-1) at 0.5 A g(-1) with 97.4% capacity retention and exhibits a 258.9 mA h g(-1) discharge capacity at 3 A g(-1) after 2500 cycles, which is 4.79 times that of a NaVO@rGO electrode and 5.9 times that of a HNaVO electrode. Meanwhile, it has a high power density of 1273.1 W kg(-1) and an energy density of 207.9 W h kg(-1) at 5 A g(-1), lighting up a light bulb by connecting two batteries in series. Furthermore, ex situ XRD and XPS techniques reveal the zinc storage mechanism of the Od-HNaVO@rGO electrode, which follows the energy storage mechanism of the co-intercalation of Zn2+ and H+ while reversibly generating the by-product Zn-3(OH)(2)V2O7 center dot 2H(2)O. Therefore, this work will open up a new way for the design of high-efficiency electrode cathode materials.

Automated summary

In this study, a one-step hydrothermal method was used to construct HNaV6O16·4H2O@reduced graphene oxide (O-d-HNaVO@rGO) electrode with oxygen-rich defects and large Zn2+ deintercalation channels. The zinc storage mechanism of the Od-HNaVO@rGO electrode was revealed through ex situ XRD and XPS techniques, showing reversible generation of by-product Zn-3(OH)(2)V2O7·2H(2)O. The Od-HNaVO@rGO battery exhibited excellent cyclic stability, high discharge capacity at high rates, and high power and energy densities, highlighting its potential as an efficient electrode cathode material.