Synthesis and electrochemical properties of hydrangea‐like (NH4)2V4O9/V5O12·6H2O cathode for zinc‐ion battery

Abstract Energy density, power density, as well as the cost of aqueous zinc‐ion batteries (AZIBs), are largely determined by the cathode material. Among the various cathodic candidates, vanadium‐based materials with various oxidation states of vanadium cations and open frameworks have emerged as highly promising options. In this work, a heterogeneous with hydrangea‐like (NH 4 ) 2 V 4 O 9 /V 5 O 12 ·6H 2 O as cathode materials for AZIBs. The hydrogen bonds formed by NH 4 + of (NH 4 ) 2 V 4 O 9 , in conjunction with the lattice water in V 5 O 12 ·6H 2 O, sufficiently strengthen the cohesion of the layered structure and expand the interlayer space. As a result, accelerating the diffusion of Zn 2+ ultimately leads to an enhanced overall discharge capacity. Remarkably, the hydrangea‐like (NH 4 ) 2 V 4 O 9 /V 5 O 12 ·6H 2 O electrode at a current density of 100 mA g −1 shows a high reversible capacity of 209 mAh g −1 after 150 cycles and higher rate capability (172 mAh g −1 at 500 mA g −1 ). The outstanding electrochemical performance can be attributed to the unique structure of the cathode material and accelerated diffusion coefficient of Zn 2+ .