NH4V3O8•0.5H2O nanobelts with intercalated water molecules as a high performance zinc ion battery cathode

Aqueous rechargeable Zn-ion batteries (ARZIBs) have been attracting huge attention recently, where V-based materials with host layer structures and fast channels enable the efficient diffusion of metal ions, leading to excellent properties of Zn2+ storage. Several ammonium vanadates have been explored as potential cathodes, and their performance in ARZIBs varies considerably. Herein, we choose H2O-intercalated NH4V3O8 (NH4V3O8 center dot 0.5H(2)O) nanobelts, which are synthesized by a low-temperature hydrothermal process, and reveal that the electrochemical performance of NH4V3O8 is strongly enhanced by the H2O molecules intercalated in the layer structure. Indeed, the NH4V3O8 center dot 0.5H(2)O nanobelts exhibit a super-high capacity of 423 mA h g(-1) at 0.1 A g(-1), together with long-term stability (50.1% retention after 1000 cycles) at 1 A g(-1). The Zn//NH4V3O8 center dot 0.5H(2)O battery thus assembled delivers a high energy density of 353 W h kg(-1) at a power density of 114 W kg(-1), comparing favorably with most of the state-of-the-art V-based cathode materials reported for ARZIBs. As a promising cathode candidate for aqueous batteries, the reversible (de)intercalation of Zn2+ in the H2O-intercalated NH4V3O8 center dot 0.5H(2)O gives rise to the formation of Zn-3(OH)(2)V2O7 center dot 2H(2)O, which helps retain the desired long-term stability.