A hydrated NH4V3O8 nanobelt electrode for superior aqueous and quasi-solid-state zinc ion batteries†
Rechargeable zinc ion batteries (ZIBs) featuring high abundance, environmental benignity, cost effectiveness, and intrinsic safety are regarded as high-potential grid energy storage systems, but the developments of high-performance cathodes with large capacity, high energy density, and long-term cyclability remain a huge challenge, owing to sluggish Zn2+ intercalation kinetics with bivalent charges in the cathodes. Herein, we report novel NH4V3O8·1.9H2O nanobelts as advanced cathode materials in aqueous and quasi-solid-state (QSS) ZIBs. When examined in aqueous ZIBs, these cathode materials enable ultrafast Zn2+ diffusion and highly reversible processes, exhibiting superior electrochemical performances with a high discharge capacity of 463 mA h g−1 at 0.1 A g−1, excellent rate capability (183 mA h g−1 even at 10 A g−1), and impressive cycling stability with a capacity retention of 81% after 2000 cycles, retaining a decent discharge capacity of 166 mA h g−1 at 10 A g−1. Moreover, the NH4V3O8·1.9H2O electrode can deliver a high energy density of 332 W h kg−1 at a power density of 72 W kg−1 and retain an energy density of 101 W h kg−1 at a high power density of 5519 W kg−1. In addition, the QSS flexible Zn/NH4V3O8·1.9H2O battery is investigated, showing durable cycling performance and stable electrochemical properties under various bending states. This study shows that the NH4V3O8·1.9H2O nanobelt cathode with high energy density and long cycle life is a potential candidate for grid energy storage systems, and it sheds light on the rational design of novel cathodes for practical rechargeable ZIBs.