Mechanistic investigation of silver vanadate as superior cathode for high rate and durable zinc-ion batteries

Recent Advancements of Graphene-Based Materials for Zinc-Based Batteries: Beyond Lithium-Ion Batteries

Graphene-based materials (GBMs) possess a unique set of properties including tunable interlayer channels, high specific surface area, and good electrical conductivity characteristics, making it a promising material of choice for making electrode in rechargeable batteries. Lithium-ion batteries (LIBs) currently dominate the commercial rechargeable battery market, but their further development has been hampered by limited lithium resources, high lithium costs, and organic electrolyte safety concerns. From the performance, safety, and cost aspects, zinc-based rechargeable batteries have become a promising alternative of rechargeable batteries. This review highlights recent advancements and development of a variety of graphene derivative-based materials and its composites, with a focus on their potential applications in rechargeable batteries such as LIBs, zinc-air batteries (ZABs), zinc-ion batteries (ZIBs), and zinc-iodine batteries (Zn-I2 Bs). Finally, there is an outlook on the challenges and future directions of this great potential research field.

How About Vanadium-Based Compounds as Cathode Materials for Aqueous Zinc Ion Batteries?

Aqueous zinc-ion batteries (AZIBs) stand out among many monovalent/multivalent metal-ion batteries as promising new energy storage devices because of their good safety, low cost, and environmental friendliness. Nevertheless, there are still many great challenges to exploring new-type cathode materials that are suitable for Zn²⁺ intercalation. Vanadium-based compounds with various structures, large layer spacing, and different oxidation states are considered suitable cathode candidates for AZIBs. Herein, the research advances in vanadium-based compounds in recent years are systematically reviewed. The preparation methods, crystal structures, electrochemical performances, and energy storage mechanisms of vanadium-based compounds (e.g., vanadium phosphates, vanadium oxides, vanadates, vanadium sulfides, and vanadium nitrides) are mainly introduced. Finally, the limitations and development prospects of vanadium-based compounds are pointed out. Vanadium-based compounds as cathode materials for AZIBs are hoped to flourish in the coming years and attract more and more researchers' attention.

AmV2O5 with Binary Phases as High-Performance Cathode Materials for Zinc-Ion Batteries: Effect of the Pre-Intercalated Cations A and Reversible Transformation of Coordination Polyhedra

In this work, five vanadium oxide materials with a series of pre-intercalated cations A (A_mV₂O₅), including Zn²⁺, Mg²⁺, NH₄⁺, Li⁺, and Ag⁺, have been successfully prepared by a two-step method. All of them possess binary monoclinic and orthorhombic V₂O₅ phases with an open layered structure that allows the ionic storage and diffusion of hydrated cations. The interlayer space for the monoclinic V₂O₅ phase is strongly dependent on the radii of hydrated cations A, while the one for the orthorhombic V₂O₅ phase remains the same regardless of the radii of cations A. Among them, A_mV₂O₅ with pre-intercalated Zn²⁺ (ZVO) has the best storage ability of Zn²⁺ with a reversible capacity close to 400 mAh g^-1, and A_mV₂O₅ with pre-intercalated Ag⁺ shows the highest rate capacity with a nearly 40% capacity retention at a current of 20 A g^-1 (≈25 C). Kinetic studies have clearly shown that pseudocapacitive behavior dominates the electrochemical reaction on ZVO. During the Zn²⁺ (de)intercalation reaction, a highly reversible transformation of binary monoclinic or orthorhombic V₂O₅ phases into a single triclinic Zn_xV₂O₅·nH₂O phase is demonstrated on ZVO. Vanadium atoms are identified as the redox centers that undergo the mutual transition among the chemical states of V³⁺, V⁴⁺, and V⁵⁺. They together with oxygen atoms constitute reasonable V-O coordination polyhedra to generate a layered structure with a suitable interlayer space for the insertion or removal of zinc ions. Actually, the intrinsic coordination chemistry changes between VO₅ square pyramids and VO₆ octahedra account for the phase transformation during the Zn²⁺-(de)intercalation reaction.

Co-intercalation strategy of constructing partial cation substitution of ammonium vanadate {(NH4)2V6O16} for stable zinc ion storage

Recently, aqueous zinc-ion batteries have become a hot research topic in the field of grid-scale application, which can be attributed to their low-cost, aqueous electrolyte and dominant theoretical reversible capacity. Nevertheless, the lack of suitable cathode materials greatly hinders the development of aqueous zinc-ion batteries. In this work, we adopt a simple one-step synthesis strategy to prepare (NH₄)₂V₆O₁₆ with an intercalation of Na⁺ and H₂O, which exhibits a novel crystal structure in which the ammonium ion, crystal water, and sodium ion co-locate in the V₃O₈ layers. The co-intercalation not only effectively enhances the binding energy between V-O layers to suppress vanadium dissolution but also successfully improves the structural stability to alleviate the structural collapse during the cyclic process. As result, (NH₄)₂V₆O₁₆ with the intercalation of crystal water and Na⁺ presents a remarkable reversible discharge capacity of 423.9 mA h g^-1 after 90 cycles at 0.1 A g^-1 with an excellent energy density of 350.3 W h kg^-1 and demonstrates an outstanding specific capacity of 182.5 mA h g^-1 at the high current density of 5 A g^-1 upon 1400 cycles during the ultra-wide voltage window of 0.1-2.0 V.

Facile Synthesis of Ag/AgVO3/N-rGO Hybrid Nanocomposites for Electrochemical Detection of Levofloxacin for Complex Biological Samples Using Screen-Printed Carbon Paste Electrodes

Silver vanadate nanorods (β-AgVO₃) with silver nanoparticles (Ag-NPs) decorated on the surface of the rods were synthesized by using simple hydrothermal technique and later anchored onto nitrogen-doped reduced graphene oxide (N-rGO) to make a novel nanocomposite. Experimental analyses were carried out to identify the electronic configuration by X-ray diffraction analysis, Fourier transform infrared spectroscopy, and X-ray photoelectron spectroscopy analysis, which revealed monoclinic patterns of the C12/m1 space group with Wulff construction forming beta silver vanadate (β-AgVO₃) crystals with optical density and phase transformations. Ag nucleation showed consistent results with metallic formation and electronic changes occurring in [AgO₅] and [AgO₃] clusters. Transmission electron microscopy and field-emission scanning electron microscopy with elemental mapping and EDX analysis of the morphology reveals the nanorod structure for β-AgVO₃ with AgNPs on the surface and sheets for N-rGO. Additionally, a novel electrochemical sensor is constructed by using Ag/AgVO₃/N-rGO on screen-printed carbon paste electrodes for the detection of antiviral drug levofloxacin (LEV) which is used as a primary antibiotic in controlling COVID-19. Using differential pulse voltammetry, LEV is determined with a low detection limit of 0.00792 nm for a linear range of 0.09-671 μM with an ultrahigh sensitivity of 152.19 μA μM^-1 cm^-2. Furthermore, modified electrode performance is tested by real-time monitoring using biological and river samples.

Reduction of silver ions in molybdates: elucidation of framework acidity as the factor controlling charge balance mechanisms in aqueous zinc-ion electrolyte

Across four molybdates, reduction of silver ions in aqueous zinc electrolyte is more facile with increasing acidity.