Activating ZnV₂O₄by an Electrochemical Oxidation Strategy for Enhanced Energy Storage in Zinc-Ion Batteries

Abstract

Rechargeable aqueous zinc-ion batteries (RAZIBs) are recognized as promising energy storage systems to meet the ever-growing demand for grid-scale applications. Developing reliable cathode materials with superior electrochemical performance plays a decisive role in this field. In this work, an electrochemical oxidation strategy is employed to successfully activate the electrochemical activity of ZnV 2 O 4 spinel oxide. Operating at high potentials up to 2.0 V enables the capacity activation process efficiently, in which the specific capacity increases from 86 to 232 mAh g −1 (corresponding to 170% capacity enhancement) after 50 cycles at 2 A g −1 . On the contrary, ZnV 2 O 4 operating in the potential window of 0.4−1.6 V only delivers 87 mAh g −1 after 50 cycles, whereas negligible capacity (<3 mAh g −1 ) is obtained in the case of 0.4−1.3 V. As characterized by X-ray diffraction (XRD), Raman microscopy, X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), and in situ pH measurements, the underlying mechanism is unraveled as a hydrolysis reaction coupled with the dissolution−recrystallization process, leading to the formation of high-valent Zn 0.06 V 2 O 5 •1.07H 2 O with a localized layered structure. The activated cathode demonstrates facilitated ion transport kinetics, reduced charge transfer resistance, and high electrochemical reversibility in RAZIBs. Benefiting from these features, stable cycle stability is achieved, that is, a reversible capacity of 138 mAh g −1 (83% capacity retention) can be retained after 2000 cycles at 4 A g −1 . This work sheds light on activating low-valent vanadium-based oxides for practical application in RAZIBs, opening an avenue for developing cathode materials for aqueous batteries.

Porous layered ZnV2O4@C synthesized based on a bimetallic MOF as a stable cathode material for aqueous zinc ion batteries

“…Meanwhile, the signal peak at 233 cm −1 coincides with the V 3 O stretching vibration mode, and the signal peaks at 890 and 944 cm −1 are corresponding to the VO 4 stretching vibration mode. These spectral vibration signal peaks are consistent with the reported spinel ZnV 2 O 4 , 19,37 implying the successful synthesis of the ZnV 2 O 4…”

“…Constructing spinel structures has become an effective strategy for regulating the electrochemical cycling performance of vanadium-based oxides due to their unique large three-dimensional skeletal structure, which can provide good three-dimensional channels for cation insertion. [16][17][18][19] For example, Wu et al 20 initially synthesized spinel Zn 3 V 3 O 8 using the sol-gel method. Due to its high zinc content and the twoelectron reaction of vanadium, it has a capacity of 285 mA h g −1 and retains 72.6% of its capacity after 2000 cycles at a 5 A g −1 current density.…”

An In Situ Electrochemical Amorphization Electrode Enables High‐Power High‐Cryogenic Capacity Aqueous Zinc‐Ion Batteries

“…It is worth pointing out that such a conversion mechanism is sharply different from the previously reported ZnV 2 O 4 electrode that converts into high-valent layered hydrates. [15] As our theoretical and experimental results indicated, the local extraction of zinc atoms would induce the reconstruction of host, leading to the phase transition from long-range ordered ZnV 2 O 4 crystalline to quantum dot-size (4-8 nm) shortrange ordered amorphous Zn 0.44 V 2 O 4 after charged to 1.6 V in the initial cycle. Benefiting from the abundant storage sites, improved Zn 2+ adsorption capability, and short diffusion path, such reconstructed amorphous electrode enables performing ultrafast reaction kinetics and excellent storage performance.…”

Cesium-doped ammonium vanadium bronze nanosheets as high capacity aqueous zinc-ion battery cathodes with long cycle life and superb rate capability

“…V 2 O 5 with expanded interlayers can provide faster ion reaction kinetics and be used for enhancing the electrochemical performance of AZIBs. 11,12 In recent years, novel vanadium-based structures have allowed aqueous zinc-ion batteries to perform well. For example, a dual redox mechanism of ions and halogens that ensures interfacial stability, 13 porous structures with lattice irregularities 14 and hydrated layered cathode materials that do not require adhesives.…”

“…V 2 O 5 with expanded interlayers can provide faster ion reaction kinetics and be used for enhancing the electrochemical performance of AZIBs. 11,12…”