Ethylene Glycol Intercalation Engineered Interplanar Spacing and Redox Activity of Ammonium Vanadate Nanoflowers as a High-Performance Cathode for Aqueous Zinc–Ion Batteries
Abstract:Ammonium vanadate (NH4V4O10) has
attracted considerable focus as a cathode material with great potential
for aqueous zinc ion batteries due to its multielectron redox reaction
of V and low cost; however, problems such as structural instability
and slow reaction kinetics during cycling hinder its widespread application.
Herein, ethylene glycol is intercalated into the interlayer of NH4V4O10 to develop high-performance cathodes
for aqueous zinc ion batteries. The layer spacing of the material
is expanded by ∼23%… Show more
“…+ ion and oxygen atom between V─O layers, multivalent states of vanadium, and extensive pathways facilitating Zn 2+ ion transport. [31,33] Besides, NH 4…”
Section: Introductionmentioning
confidence: 99%
“…[ 16,31,32 ] Its broad appeal stems from the robust interaction between NH 4 + ion and oxygen atom between V─O layers, multivalent states of vanadium, and extensive pathways facilitating Zn 2+ ion transport. [ 31,33 ] Besides, NH 4 + has a large ionic radius (1.43 Å) and a low molar mass (18 g mol −1 ), which could provide high mass and volume specific capacities when acting as a pre‐inserted layer ion. [ 34 ] However, the strong electrostatic attraction between the small‐radius Zn 2+ (0.76 Å) and the highly electronegative oxygen atoms poses a challenge Zn 2+ ions readily associate with these highly electronegative oxygen atoms within the V─O layers.…”
Ammonium vanadates, featuring an N─H···O hydrogen bond network structure between NH4+ and V─O layers, have become popular cathode materials for aqueous zinc‐ion batteries (AZIBs). Their appeal lies in their multi‐electron transfer, high specific capacity, and facile synthesis. However, a major drawback arises as Zn2+ ions tend to form bonds with electronegative oxygen atoms between V─O layers during cycling, leading to irreversible structural collapse. Herein, Li+ pre‐insertion into the intermediate layer of NH4V4O10 is proposed to enhance the electrochemical activity of ammonium vanadate cathodes for AZIBs, which extends the interlayer distance of NH4V4O10 to 9.8 Å and offers large interlaminar channels for Zn2+ (de)intercalation. Moreover, Li+ intercalation weakens the crystallinity, transforms the micromorphology from non‐nanostructured strips to ultrathin nanosheets, and increases the level of oxygen defects, thus exposing more active sites for ion and electron transport, facilitating electrolyte penetration, and improving electrochemical kinetics of electrode. In addition, the introduction of Li+ significantly reduces the bandgap by 0.18 eV, enhancing electron transfer in redox reactions. Leveraging these unique advantages, the Li+ pre‐intercalated NH4V4O10 cathode exhibits a high reversible capacity of 486.1 mAh g−1 at 0.5 A g−1 and an impressive capacity retention rate of 72% after 5,000 cycles at 5 A g−1.
“…+ ion and oxygen atom between V─O layers, multivalent states of vanadium, and extensive pathways facilitating Zn 2+ ion transport. [31,33] Besides, NH 4…”
Section: Introductionmentioning
confidence: 99%
“…[ 16,31,32 ] Its broad appeal stems from the robust interaction between NH 4 + ion and oxygen atom between V─O layers, multivalent states of vanadium, and extensive pathways facilitating Zn 2+ ion transport. [ 31,33 ] Besides, NH 4 + has a large ionic radius (1.43 Å) and a low molar mass (18 g mol −1 ), which could provide high mass and volume specific capacities when acting as a pre‐inserted layer ion. [ 34 ] However, the strong electrostatic attraction between the small‐radius Zn 2+ (0.76 Å) and the highly electronegative oxygen atoms poses a challenge Zn 2+ ions readily associate with these highly electronegative oxygen atoms within the V─O layers.…”
Ammonium vanadates, featuring an N─H···O hydrogen bond network structure between NH4+ and V─O layers, have become popular cathode materials for aqueous zinc‐ion batteries (AZIBs). Their appeal lies in their multi‐electron transfer, high specific capacity, and facile synthesis. However, a major drawback arises as Zn2+ ions tend to form bonds with electronegative oxygen atoms between V─O layers during cycling, leading to irreversible structural collapse. Herein, Li+ pre‐insertion into the intermediate layer of NH4V4O10 is proposed to enhance the electrochemical activity of ammonium vanadate cathodes for AZIBs, which extends the interlayer distance of NH4V4O10 to 9.8 Å and offers large interlaminar channels for Zn2+ (de)intercalation. Moreover, Li+ intercalation weakens the crystallinity, transforms the micromorphology from non‐nanostructured strips to ultrathin nanosheets, and increases the level of oxygen defects, thus exposing more active sites for ion and electron transport, facilitating electrolyte penetration, and improving electrochemical kinetics of electrode. In addition, the introduction of Li+ significantly reduces the bandgap by 0.18 eV, enhancing electron transfer in redox reactions. Leveraging these unique advantages, the Li+ pre‐intercalated NH4V4O10 cathode exhibits a high reversible capacity of 486.1 mAh g−1 at 0.5 A g−1 and an impressive capacity retention rate of 72% after 5,000 cycles at 5 A g−1.
Aqueous zinc‐ion batteries, considered one of the important candidate technologies for green and environmentally friendly large‐scale energy storage, hinge upon the performance of cathode materials as the key factor driving their development. Vanadate oxide is a promising cathode material due to its high theoretical capacity; furthermore, in order to accelerate the reaction kinetics, ion or molecular intercalation is often utilized. However, non‐electrochemically active intercalants tend to cause capacity degradation. In this study, a one‐step hydrothermal method is employed to intercalate electrochemically active poly‐o‐phenylenediamine (PoPDA) into the interlayers of NH4V3O8 (NVO), with graphene oxide (GO) being used to further improve the conductivity of the composite material (NVO/PoPDA@GO). The insertion of PoPDA expands the interlayer spacing of the NVO, alters the charge distribution, and enhances the migration rate of Zn2+ among the hybrid materials. Additionally, PoPDA serves as a support within the interlayers, improving the material stability. Moreover, the reversible transformation and rearrangement of chemical bonds (C═N/C─N) in PoPDA allows for coordination with Zn2+, providing additional capacity. As a result, NVO/PoPDA@GO exhibits excellent electrochemical performance, releasing a specific capacity of 433 mAh g−1 at 0.5 A g−1, even with a capacity of 224 mAh g−1 at 5 A g−1. This work provides a promising direction for the preparation of organic–inorganic composite cathode materials with dual active components.
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