Facile hydrothermal synthesis and electrochemical properties of (NH4)2V6O16 nanobelts for aqueous rechargeable zinc ion batteries

Aqueous rechargeable Zn-ion batteries (ARZIBs) have attracted great attention owing to many advantages including environmental protection, low cost and safety. Ammonium vanadates with multi-oxidation valence and open-framework layered structure, which is beneficial for zinc storage performance, are chosen as alternative candidates of cathode materials. (NH4)2V6O16 has received some attention in Li-ion battery, however, the electrochemical properties of (NH4)2V6O16 applied to ARZIBs has rarely reported comparatively. In this work, (NH4)2V6O16 nanobelts are prepared through a facile hydrothermal method and reported as the cathode material in ARZIBs. The Zn/(NH4)2V6O16 battery displays a wonderful rate capability with a staged reversible capacity of 322.0, 300.8, 267.5, 239.3, 209.2 mA h g−1 at 0.1, 0.2, 0.5, 1, 2 A g−1, respectively. The battery exhibits a high energy density (249 W h kg−1) and a long-term reversible cycling performance (78.3 % retained at 5 A g−1 after 2000 cycles). The complete morphology of (NH4)2V6O16 after long-term cycle also illustrates its good flexibility during Zn2+ insertion/extraction without structural damage. Multiple analytical measurements methods are applied to investigate the major reaction mechanisms of the Zn2+ reversible (de)intercalation. The results demonstrate that the (NH4)2V6O16 as a cathode substitute is very promising for ARZIBs or other advanced battery systems.