Ethylene Glycol Intercalation Engineered Interplanar Spacing and Redox Activity of Ammonium Vanadate Nanoflowers as a High-Performance Cathode for Aqueous Zinc-Ion Batteries

Ammonium vanadate (NH4V4O10) hasattracted considerable focus as a cathode material with great potentialfor aqueous zinc ion batteries due to its multielectron redox reactionof V and low cost; however, problems such as structural instabilityand slow reaction kinetics during cycling hinder its widespread application.Herein, ethylene glycol is intercalated into the interlayer of NH4V4O10 to develop high-performance cathodesfor aqueous zinc ion batteries. The layer spacing of the materialis expanded by & SIM;23% after the intercalation of ethylene glycol,providing a large interlaminar channel for Zn2+ diffusion,while the addition of ethylene glycol leads to the micromorphologyof nanoflowers self-assembled by ultrathin nanosheets, exposing moreactive sites for ion and electron transport. Moreover, the successfulpartial substitution of ethylene glycol for NH4 (+) in the NH4V4O10-based materialresults in an increase in the level of V5+ and alleviatesirreversible deamination, promoting efficient redox reactions. Inaddition, the introduction of ethylene glycol efficiently decreasesthe band gap of NH4V4O10 and, thus,improves the conductivity. As a result, the ethylene glycol-intercalatedNH(4)V(4)O(10) cathode provides a highreversible capacity of 516 mAh g(-1) at 0.5 A g(-1) and achieves an excellent cycling performance witha capacity retention rate of 91% after 1000 cycles at 10 A g(-1). This work provides a feasible strategy to develop high-performancelayered V-based cathodes for AZIBs by the coregulation of crystalstructure, micromorphology, and redox chemistry. Ethylene glycol intercalation expands interplanar spacingand promotes redox activity of NH4V4O10 as a high-performance cathode for aqueous zinc-ion batteries.