Investigation of Na6V10O28 as a promising rechargeable aqueous zinc-ion batteries cathode

For cost and safety reasons, aqueous batteries are suitable for large-scale energy storage. Among all aqueous batteries, rechargeable aqueous zinc-ion batteries (ZIBs) are promising choices owing to the low equilibrium potential and high volumetric capacity of zinc. However, its development is also severely hindered by the limited available cathode materials, which generally display poor cycling capabilities. As one of the most investigated POVs (polyvanadates) today, (V 10 O 28 ) 6− has been demonstrated to be feasible in energy storage rely on the well-defined structure and fascinating material activity. Herein, we propose a polyvanadate-Na 6 V 10 O 28 with (V 10 O 28 ) 6− anion as a support structure and serve it for the first time as an aqueous ZIBs cathode. The high stability of the (V 10 O 28 ) 6− cluster permits the material to tolerate the reversible (de)insertion of Zn 2+ . As a result, the Na 6 V 10 O 28 cathode delivers a high capacity of 279.5 mAh g −1 after activation and an extraordinary lifespan over 2000 cycles. Furthermore, the pseudocapacitance analysis and GITT test reveal the pseudocapacitance behavior and high Zn 2+ diffusion coefficient (10 −10 cm 2 s −1 ) of the Na 6 V 10 O 28 /Zn cell, respectively. Not only that, ex-situ XRD, XPS, and TEM are also employed to analyze the storage mechanism of Zn 2+ , indicating the synergistic zinc-storage capacity of Na 6 V 10 O 28 and irreversible products. Overall, this work presents new insights into the application of Na 6 V 10 O 28 in aqueous ZIBs and also demonstrates the competitive potential of POVs for energy storage.