Green Synthesis of Vanadate Nanobelts at Room Temperature for Superior Aqueous Rechargeable Zinc-Ion Batteries

Rechargeable aqueous zinc-ion batteries are emerging as new promising energy storage devices for potential grid-scale applications, owing to their high safety and low cost. However, the limited choice of cathode materials and lack of green and scalable synthesis strategies have largely hindered their practical applications. Herein, a universal synthesis approach is developed to produce a variety of nanostructured layered vanadates, i.e., nanobelts of NaV3O8·1.35H2O (NVO), Zn3V2O8·1.85H2O (ZnVO), and KV3O8·0.51H2O (KVO), at room temperature. When examined as new cathodes for the zinc-ion battery system with aqueous ZnSO4 as electrolyte, all three nanobelts exhibit excellent electrochemical performances, particularly the NVO and ZnVO electrodes, delivering high specific capacities of 366 and 328 mAh g–1 at 0.1 A g–1, respectively. In addition, at an ultrahigh current density of 10 A g–1, the NVO shows an initial capacity of 186 mAh g–1 with retained capacity of 200 mAh g–1 after 200 cycles, while ZnVO provides an initial capacity of 205 mAh g–1 with retained capacity of 191 mAh g–1. Such remarkable electrochemical performances make layered vanadates, especially the NVO and ZnVO, very promising cathode candidates for new-generation aqueous zinc-ion batteries.