Vanadate Electrode Research Articles

Sodium Vanadates for Metal-Ion Batteries: Recent Advances and Perspectives.

Rechargeable metal-ion batteries (MIBs) play a pivotal role in advancing the stable supply of renewable energy by efficiently storing and discharging electrical energy. In recent years, to propel the continuous advancement of MIB technology, numerous studies have concentrated on exploring and innovating electrode materials, aiming to engineer commercial batteries with high energy density, superior power density, and extended cycle life. Notably, sodium vanadates have garnered significant attention in the realm of MIBs owing to their distinctive crystal structures, abundant resource reservoirs, and exceptional electrochemical properties. This paper provides a prompt and comprehensive review of the research landscape for various sodium vanadates (such as NaxV2O5, Na1+ xV3O8, Na2V6O16·xH2O, etc.) in the domain of MIBs over the past five years. It delves into the structural characteristics, electrochemical performances, and energy storage mechanisms of these materials, while also proposing some effective strategies to augment their electrochemical capabilities. Building upon these insights and prevailing research outcomes, this review envisions the future developmental pathways of sodium vanadates for MIBs and aims to reveal the vast potential of sodium vanadates in the emerging energy storage field and provide researchers with clear insights and perspectives for developing optimal sodium vanadate electrodes.

Regulating oxygen vacancies in ammonium vanadate electrode materials for advanced aqueous zinc ion batteries

In the past decade, vanadates have attracted one's attention as the electrode materials for aqueous zinc ion batteries (AZIBs). Nevertheless, their structural instability and sluggish ion/electron dynamics lead to an inevitable decline in the electrochemical performance. To address these issues, we introduce oxygen vacancies into NH4V4O10 nanosheets to improve the ion transport rate during the electrochemical reaction. The prepared NHVO-40 samples provide many active sites compared to NH4V4O10 materials. The assembled cell delivers a capacity of 452.03 mAh g-1 at a current density of 0.2 A g-1. It also presents a retention rate of 94.6% at 10 A g-1 after 4000 times cycling. In addition, they still possess an energy density of 332.5 Wh kg-1 at a power density of 70W kg-1.

High-performance battery type bismuth vanadate electrodes for supercapacitors

High-performance battery type bismuth vanadate electrodes for supercapacitors

Largely improved cycling stability of CoV2O6 supercapacitor electrode synthesized by deep eutectic solvent

Transition metal oxides composed of cobalt-based and vanadate configurations are widely used in supercapacitor electrodes due to the abundant nature of the various elements and their outstanding electrochemical performance. However, redox and ion intercalation mechanisms are involved between the electrodes and electrolyte, which inevitably lead to large differences in capacity retention and long-term cycling ability of synthetic electrodes by different preparation methods. In this work, the CoV2O6 electrode with a capacity of 194.0 C g−1 and a capacitance retention of 122.2 % after performing 100,000 cycles was synthesized by using deep eutectic solvent. In addition, the underlying mechanism of its excellent cycling stability was systematically studied. It was demonstrated that the continuous growth of particles on the electrode surface could lead to the formation of a stable polyhedron structure. More specifically, the generation of the CoOOH phase with strong reversibility on the electrode surface is considered the key to attaining the long cycling life of the CoV2O6 electrode. A hybrid supercapacitor (CoV2O6//AC HSC) was assembled for the evaluation of practical applications. It delivers a specific capacity of 119.3 C g−1 as well as a rate capability with 92.3 % capacity retention and good cycling durability, and the energy density of the HSC can reach up to a high energy density of 20.6 W h kg−1 at 373.4 W kg−1. A new cobalt vanadate electrode synthesis method was proposed here to examine the changes in the specific capacity and capacitance retention after performing ultra-long cycles, which provide a solid experimental basis for the development of supercapacitors for practical applications.

Gallium Ion Pre‐Insertion Protocol to (NH4)2V10O25·8H2O Cathode Materials for Reversible Aqueous Zn Battery

AbstractVanadate is one of the promising cathode materials for aqueous zinc ion batteries (AZIBs) due to its abundant resources and various valence states. However, the further development is restricted by their sluggish reaction kinetics between zinc ions and the host materials. In this work, several kinds of gallium ions pre‐intercalated vanadate electrode materials through a simple hydrothermal strategy are designed. Ga‐NHVO‐0.5 sample achieves a specific capacity of 438.23 mAh g−1 at current density of 0.2 A g−1. At the same time, it delivers an energy density of 250.34 Wh kg−1 at a power density of 55 W kg−1. The assembled button cells retain 83.84% of its initial capacity after 4000 times cycling, revealing their promising applications in portable power devices. Moreover, the devices still possess a favorable stability under different bending conditions.

A high-performance C@Na5V12O32 nanowire electrode derived from the reconstruction of carbon quantum dots.

Vanadate electrodes are potential candidates for lithium-ion batteries (LIBs) due to their large theoretical specific capacity. However, their easy dissolution in the electrolyte, large structural changes, low conductivity and capacity decay during cycling hinder their further application. Herein, a lithium-ion battery electrode of Na5V12O32 (NVO) nanowires covered with a carbon film and formed by the reconstruction of carbon quantum dots (CDs) was obtained using an in situ capping strategy. Remarkably, the carbon film could prevent direct contact between the NVO nanowires and the electrolyte, thus slowing down the occurrence of side reactions and avoiding the dissolution of the NVO nanowires. Among the electrodes treated at different temperatures, the C@NVO-400 electrode exhibits high capacity and excellent cycling stability as the electrode of LIBs, with a discharge specific capacity of 779.1 and 315.5 mAh g-1 after 400 and 1000 cycles at a current density of 0.1 and 2 A g-1, respectively. An in situ coating strategy is proposed here to contribute to the further development of coated vanadate electrodes for high-performance LIBs.

Chitosan-induced NH4V4O10 hierarchical hybrids as high-capacity cathode for aqueous zinc ion batteries.

Aqueous zinc ion batteries (AZIBs) have been widely investigated due to their characteristics of convenient operation and intrinsic safety. However, there are several issues to be addressed in AZIBs, such as slow diffusion kinetics of Zn2+, cathode material dissolution and the dendrite formation of zinc anodes. Thus, it is challenging to prepare a high-performance cathode material. In this work, we prepare NH4V4O10 flower-like structures by a facile hydrothermal route. The introduction of chitosan significantly enlarges the layer spacing of the (001) crystal plane. The assembled Zn//NVO-0.15C batteries deliver a specific capacity of 520.54 mA h g-1 at a current density of 0.2 A g-1. Furthermore, they maintain 91% of the retention rate at 5.0 A g-1 after 1000 times cycling. It demonstrates the excellent zinc ion storage behavior of ammonium vanadate electrode materials for AZIBs.

Ionic liquids-assisted electrolytes in aqueous zinc ion batteries

In the quest for safer and low-cost batteries, zinc ion batteries have remarkable potential in various energy storage applications. However, selecting suitable electrolytes for zinc electrochemistry is challenging due to zinc's passivation and dendritic growth hindering long-term stability. Moreover, the synergy between newly developed electrode materials and electrolytes remains challenging for commercial applications. Therefore, in this study fifty (50) combinations of ionic liquids (ILs) were screened using COSMO-RS simulation to identify suitable ILs for aqueous electrolytes with ZnSO4 salt by comparing activity coefficients at infinite dilution, selectivity, and capacity of ILs to dissolve ZnSO4 salt in the aqueous phase. Further, calcium vanadate (CaV2O6) was synthesized using a modified molten salt method and characterized using a Scanning Electron Microscope and X-ray diffraction to confirm its successful synthesis. Afterwards, the performance of calcium vanadate in aqueous zinc batteries having ILs-assisted electrolytes were also evaluated and compared with conventional electrolyte (aqueous 1 M ZnSO4). Results revealed that ILs based on tetramethyl ammonium cation were suitable for electrolyte applications with ZnSO4 salt. Furthermore, Tetramethylammonium hydrogen sulfate was compared with conventional ZnSO4 electrolyte and an initial discharge capacity of 330 mAh/g for calcium vanadate electrode with ILs-assisted electrolyte was observed as compared to 230 mAh/g with 1 M ZnSO4 aqueous electrolyte. Electrochemical impedance spectroscopy (EIS) measurements showed that ILs-assisted electrolyte's charge transfer and surface film resistance were lower than the conventional electrolyte. However, additional advancement in electrode and electrolytes, i.e. synthesis of electrode materials, and formulation of ILs-assisted electrolytes, may further improve the performance of aqueous zinc ion batteries.

Predominated capacitive behavior of Ag-doped magnesium vanadate as a novel electrode material for supercapacitors

Transition metal vanadate nanostructures are getting significant importance as an efficient electrode material for modern energy storage applications. In this work, a simple hydrothermal method is employed for the synthesis of magnesium vanadate (MgV2O5) and Ag-doped magnesium vanadate (Ag doped MgV3O8) nanomaterials. The X-ray diffraction (XRD) analysis reveals the formation of an orthorhombic structure for magnesium vanadate, whereas the Ag-doped magnesium vanadate results in a monoclinic structure. Interestingly, the optical bandgap is observed to increase from 2.85 eV to 3.92 eV with the increase in Ag-doping as revealed from Tauc's plot of the UV-visible absorption spectrum. The electrochemical performance of magnesium vanadate electrodes is thoroughly investigated by cyclic voltammetry (CV), Galvanostatic charge-discharge (GCD), and electrochemical impedance spectroscopy. The Ag-doped magnesium vanadate shows higher specific capacitance (Cs = 706 Fg−1) in comparison to undoped (325 Fg−1) at a current density J = 5 Ag−1. The theoretical investigations through Dunn's model demonstrate a major contribution arises from surface-controlled processes, which increase as high as 91% at scan rate of 60 mVsec−1. Our findings indicate that Ag-doping significantly improves the overall electrochemical response of magnesium vanadate as an efficient electrode material for supercapacitor applications.

P-doping boosting electronic properties and ionic kinetics of MnV2O6 for high-performance lithium-ion batteries.

Vanadate electrodes are potential candidates for lithium-ion batteries (LIBs) due to their large theoretical specific capacity. However, their practical application suffers from limitations of poor conductivity, inferior ion kinetics, and severe volume changes upon cycling. Herein, a doping strategy is realized to prepare phosphorus (P)-doped MnV2O6 (PMVO) nanosheets to enhance the electrochemical activity and structural stability. On combining experimental and computation results, it is found that the PMVO structure enhances the electrical conductivity, reduces the adsorption energy of lithium ions, increases the structural stability, and facilitates rapid surface diffusion kinetics. As expected, the desirable electrode of PMVO delivers a reversible capacity of 812.7 mA h g-1 at 200 mA g-1 and shows excellent coulombic efficiency, as well as an extraordinary energy density of 472.1 W h kg-1. Meanwhile, an excellent rate performance (from 0.1 to 5.0 and return to 0.1 A g-1; 779.6 to 319.6 and return to 811.9 mA h g-1) could be achieved. The strategy proposed here may aid in further development of doped vanadate electrodes for high-performance LIBs.

Ammonium vanadate electrode materials with stable layered structures for rechargeable zinc ion batteries

We prepared NHVO-1 nanobelts with C2H2O4·2H2O as a reducing agent by a simple hydrothermal strategy. The assembled cells deliver an energy density of 370.08 W h kg−1at a power density of 120 W kg−1and can maintain 87% of the initial capacity after 2000 cycles at 2 A g−1.

Aqueous zinc ion batteries based on sodium vanadate electrode materials with long lifespan and high energy density

We have prepared Na7V7.6O20·4H2O (NVO) nanobelts by a facile hydrothermal route. The assembled NVO/Zn batteries deliver a capacity of 309.4 mA h g−1 at 0.3 A g−1 and maintain excellent cycling stability after 10 000 cycles at 10 A g−1.

Studies on electrochemical mechanism of nanostructured cobalt vanadate electrode material for pseudocapacitors

The supercapacitive behaviour of chemically synthesized cobalt vanadate nanostructures was reported in this work. Various analytical techniques along with optical studies were utilized to investigate the crystallographic information's and optical response. Crystallographic information of the prepared nanostructures was revealed by the XRD analysis and it's formation was confirmed by the FTIR and XPS techniques. The nano-layered structural and surface morphology was observed through scanning electron microscopy and high-resolution transmission electron microscopy. Electrochemical performances in aqueous electrolytic medium were examined for supercapacitive behaviour of prepared Co3V2O8. Specific capacitance value of about 790 F/g was achieved at 1 A/g current density and the superior capacitive retention of 90.1 % after 10000 cycles had been imparted by the prepared Co3V2O8. Based on the results, it was confirmed that the prepared cobalt vanadate nanostructures can be used as an electrode material for future energy storage devices.

Gradient oxygen vacancies in BiVO4 olive-seeds nanostructure for electrochemical supercapacitor applications

In recent years, humans' increasing necessity and consumption of energy and the lack of energy-related issues have drawn considerable attention due to high power density, cyclic performance, and highly safe. Herein, we have designed and reported new Olive-Bismuth vanadate (O-BV) electrodes serving as excellent electrochemical materials for supercapacitors prepared by a simple solvothermal method. The supercapacitive features were examined by cyclic voltammetry (CV) and chronopotentiometry (CP) techniques. The cyclic voltammetric analyses were performed using three different electrolytes, including aqueous Na2SO4, KOH, and NaOH electrolyte solution in 1 M concentration. The as-prepared O-BV electrode exhibits a significant specific capacitance of 977 Fg-1 at a scan of 5 m V−1 in 1 M NaOH electrolyte solution. Furthermore, the Olive-Bismuth vanadate electrode was achieved outstanding performance of cyclic stability after 2000 cycles and retained 86% of its initial capacitance. The excellent specific capacitance and superior cyclic stability highlight the potential of the Olive-Bismuth vanadate material as an active electrode for high-performance supercapacitors.

Effect of anions on the copper vanadate structure during ion-exchange and its lithium storage performance

Copper vanadate materials have a higher gravimetric capacity and energy density than those of the traditional vanadium oxide or vanadate electrodes because of the multistep oxidation-reduction reactions. This work presents the synthesis of nano-structured copper vanadates using ion-exchange reaction of sodium vanadate nanowire arrays in an aqueous solution, containing copper acetate or copper nitrate. The morphology, crystal structure, composition and lithium-storage performance of the materials are measured and characterized thoroughly. Due to the dissolution effect of the acetate anion on the sodium vanadate nanowire arrays, copper vanadate spheres composed of nanosheets are produced. By contrast, after the ion-exchange reaction in the copper nitrate solution, the sample maintains its original nanowire arrays structure. The copper vanadate nanowire arrays synthesized in copper nitrate solution for 48 h followed with calcination at 300 °C for 2 h exhibit a remarkably high storage capacity of up to 997.76 mAh g−1 in 3–0.01 V versus Li/Li+, thus showing a great potential for application in lithium-ion batteries.

Effects of molecular modifications for water splitting enhancement of BiVO4

Combined organic (molecular adsorption) and inorganic (TiO2 passivation) modifications for enhancing water splitting efficiency of porous bismuth vanadate electrodes are tested. The catalytic activity of BiVO4 is increased after adsorption of a newly prepared ruthenium catalyst. TiO2 passivation and sensitization with RuP dye does not show straightforward improvements to the complex photocatalytic behaviour depending on the configuration of the (two- or three-electrode) photoelectrochemical cell, type of the experiment and sample aging. The time constant for electron transport in BiVO4 electrodes (in the range of seconds, revealed by electrochemical impedance measurements) was found to correlate with the stable photocurrent of the cells. The femtosecond transient absorption studies confirm the negligible effects of RuP on the population of the photoexcited carriers in BiVO4. The transient absorption studies also show that the processes responsible for the differences in photocurrents of the modified BiVO4 samples occur on a time scale longer than the first nanoseconds.

Facile synthesis of Mn2.1V0.9O4/rGO: A novel high-rate anode material for lithium-ion batteries

The development of novel manganese vanadate electrode materials with high capacity and good rate capability is a great challenge. In this work, a novel manganese vanadate grown on reduced graphene oxide is successfully prepared by a fast and facile approach. Small Mn2.1V0.9O4 particles (20–50 nm) are anchored on reduced graphene oxide, which significantly alleviates volume changes and improves electrical conductivity and lithium ion transfer. In addition, the strong chemical interactions between Mn2.1V0.9O4 and reduced graphene oxide are conducive to accelerate charge transfer. These features are favorable for achieving high reversible capacity and excellent rate performance. As an anode for lithium-ion batteries, a high discharge capacity of 981 mA h g−1 is retained after 80 cycles at 100 mA g−1. Even at 2000 mA g−1, a high capacity of 748 mA h g−1 is achieved. New prospects are brought by this work for the synthesis and the potential application of manganese vanadate materials.

Improving the photoelectrochemical catalytic ability of bismuth vanadate electrodes by depositing efficient Co-catalysts

Depositing effective co-catalysts with an excellent electrocatalytic ability is one of the most efficient ways to solve the serious surface charge recombination for BiVO4 as the photocatalyst toward water oxidation. Five cheap co-catalysts based on nickel, cobalt and iron were synthesized and deposited on BiVO4 electrodes using hydrothermal synthesis and electrodeposition methods. The negatively shifted onset potentials and higher photocurrent densities were obtained for the BiVO4 electrodes with co-catalyst depositions. The best photoelectrochemical performance toward catalysing water oxidation was attained for the NiOOH/BiVO4 electrode, owing to the better intrinsic properties of NiOOH and the continuous film on the BiVO4 surface to improve the connection between nanoparticles. The loading amount of NiOOH on the BiVO4 electrode was optimized by varying the photo-assisted electrodeposition times. The NiOOH/BiVO4 electrode prepared using 15 min for the photo-assisted electrodeposition showed the highest photocurrent density of 2.10 mA/cm2 at 1.23 V versus reversible hydrogen electrode under air mass 1.5 global illumination. The BiVO4 electrode without the co-catalyst deposition only presented a photocurrent density of 0.30 mA/cm2 measured at the same conditions. The negatively shifted onset potential, smaller charge transfer resistance and the better long-term stability were also attained for the NiOOH/BiVO4 electrode. The excellent photoelectrochemical catalytic ability for the NiOOH/BiVO4 electrode is primarily owing to the reduced surface charge recombination and the continuous film of NiOOH on the BiVO4 electrode for achieving better connection between nanoparticles. This study confirms the function of co-catalysts and provides a systematic comparison of cheap co-catalysts deposited on the promising monoclinic BiVO4 electrode on the enhancement of the photoelectrochemical catalytic performance toward water oxidation. It is also suggested that the adequate deposition amount of the co-catalyst is of the great importance for improving the catalytic ability of the co-catalyst/photocatalyst system.

Direct Growth of BiVO4/Bi2S3 Nanorod Array on Conductive Glass as Photocatalyst for Enhancing the Photoelectrochemical Performance

Photoelectrochemical water splitting is one of the promising methods to generate hydrogen fuels. Designing photocatalysts for accelerating four-electron transfer water oxidation is necessary to improve photoelectrochemical water splitting. Bismuth vanadate is one of the efficient photocatalysts for water oxidation, but the short diffusion length limits its photocatalytic ability. This work first proposes synthesis of bismuth sulfide/bismuth vanadate nanorod array on conducting glass via solution method and hydrothermal reaction to enhance visible-light absorption and provide efficient charge-transfer with type II heterojunction and one-dimensional transfer path. Bismuth sulfide coverage on bismuth vanadate nanorod array is simply tuned by varying thiourea amounts in hydrothermal solution. Higher photocurrent density of 1.43 mA/cm2 are obtained for bismuth sulfide/bismuth vanadate electrode than that for bismuth vanadate electrode (0.25 mA/cm2) at 1.23 V versus reversible hydrogen electrode, measured under...

Porous iron vanadate nanowire arrays on Ti foil as a high-performance lithium-ion battery

The nanostructuring of materials can solve the problem of low conductivity of the vanadate electrode, thereby increasing the potential for lithium storage performance. The traditional battery is prepared by coating active materials on current collector, which produces large contact resistance between the current collector and the electrodes, impeding the overall electrochemical performances of the battery. In this work, we propose and verify a scheme for directly loading porous iron vanadate nanowire array electrode on titanium foil. The resultant electrode (the as-prepared iron vanadate annealed at 300 °C) exhibits an enhanced lithium storage performance, the discharge capacity after 100 cycles is 1041.10 mAh·g−1 at a current density of 300 mA·g−1. The iron vanadate nanowire electrode is fabricated by a simple and scalable cation-exchange method, which can be provided for the separate and integrated large-scale industrialization of vanadate electrode materials.