Vanadium Oxide Research Articles

Experimental Validation of Density Functional Theory Predictions on Structural Water Impact in Vanadium Oxide Cathodes for Zinc-Ion Batteries.

This study combines experimental methods with density flooding theory (DFT) calculations to investigate the enhancement of the electrochemical performance of vanadium oxide cathodes for aqueous zinc ion batteries (AZIBs) through strategic water content management. DFT predictions indicated that a moderate presence of structural water optimizes electrical conductivity and facilitates zinc ion diffusion. These theoretical insights are empirically validated by synthesizing AlVO-1.6 H2O using a hydrothermal method, which exhibited superior electrochemical properties. This material demonstrated an impressive initial capacity of 316 mAh g-1 at 0.2 A g-1, with robust capacity retention after extended cycling. Remarkably, even at an elevated current density of 10 A g-1, it sustains a capacity of 161.6 mAh g-1, while maintaining a capacity retention of 97.6% over 2000 cycles. The results confirm that adjusting the structural water content in vanadium oxides significantly boosts their electrochemical capabilities, aligning experimental outcomes with computational forecasts and showcasing a novel approach for developing high-performance cathodes in energy storage technologies.

Fabrication of Vanadium Oxide-encapsulated Hybrid Carbon Nanospheres for Enhanced Tribological Performance.

A new sulfur-containing carbon nanospheres encapsulated with vanadium oxide (V@SCN) is synthesized through a one-pot oxidation polymerization and then carbonization method. The prepared V@SCNs exhibit good dispersibility as a lubricant additive, which is owing to the inherited lipophilic organic functional groups in the sulfur-containing carbon shell derived from the carbonization of polythiophene. The agglomeration and precipitation of metals in the base oil are also avoided through the encapsulation of lipophilic carbon shells. The stress and thermal simulation results show that the vanadium oxide core bestows upon the carbon nanospheres enhanced load resistance and superior thermal conductivity, which contributes to their excellent tribological properties. Introducing 0.04M-V@SCN to the base oil leads to favorable tribological characteristics, such as a fourfold rise in extreme pressure capacity from 250 to 1050N, a reduction in friction coefficient from 0.2 to ≈0.1, and a substantial decrease in wear by 90.2%. The lubrication mechanism of V@SCNs as lubricant additive involves the formation of a robust protective film on the friction pair, which is formed via complex physical and chemical reactions with the friction pair during friction.

Tuning Optical and Electrical Properties of Vanadium Oxide with Topochemical Reduction and Substitutional Tin

Tuning Optical and Electrical Properties of Vanadium Oxide with Topochemical Reduction and Substitutional Tin

Evaluating the Intrinsic Zinc Storage Capacity of Cation-Preintercalated Cathode with Electrochemically Active Surface Area.

The guest cation preintercalation strategy has been widely adopted to improve the performance of zinc-vanadium batteries. However, existing studies always ignore the deintercalation of guest cations. This work focuses on the severe and universal deintercalation phenomenon and confirms the unaltered capacity after deintercalation, indicating that the capacity improvement mechanism cannot be attributed to the role of guest cations. Therefore, after excluding all of the previously researched factors for capacity improvement, the decisive factor is identified as the morphology (surface area). Based on the electrochemically active surface area (ECSA), a quantitative relationship with intrinsic capacity is established for the first time. This guides us to enhance battery capacity via enhancing ECSA through liquid-phase ultrasonic crushing to achieve the highest capacity of cation-preintercalated V2O5·nH2O (333.7 mAh g-1 at 10 A g-1). We believe that the enhanced ECSA is a plausible explanation for the improved performance of hydrated vanadium oxides.

Ab initio investigation of ZnV2O4, ZnV2S4, and ZnV2Se4 as cathode materials for aqueous zinc-ion batteries

Zinc-ion batteries (ZIBs) employing aqueous electrolytes have emerged as one of the most promising alternatives to lithium-ion batteries (LIBs). Nonetheless, the development of ZIBs is hindered by the scarcity of cathode materials with suitable electrochemical properties. In this work, we investigate the unique properties of zinc vanadate oxide (ZnV2O4, ZVO) and zinc vanadate sulfide (ZnV2S4, ZVS) compounds as cathode materials, focusing on their crystal structures, electrochemical performance, spectroscopic features and potential applications in ZIBs. Additionally, we investigate a new cathode material, zinc vanadate selenide (ZnV2Se4, ZVSe), constructed by replacing sulfur with selenium in the ZVS cubic structure. Our findings reveal that these compounds exhibit distinct electronic and electrochemical properties, although they have similar magnetic properties due to the fact that vanadium has the same oxidation state in all three compounds. On average, ZVS stands out as the most promising candidate for ZIBs cathodes, followed by ZVO. ZVSe, shows lower electrochemical performance and also has the obvious drawback of being more costly than the sulfur- and oxygen-based compounds. Our theoretical results align closely with available experimental data, both for electrochemical properties as well as x-ray and photoelectron spectroscopy, where a comparison can be made.

Modified structure of vanadium oxide via cadmium doping and in-situ activation for high-performance aqueous zinc ion storage

Vanadium oxides are promising cathode materials for aqueous zinc-ion batteries, but they suffer from severe crystal collapse and poor electrical/ionic conductivity. Herein, we successfully synthesized the designed cadmium-doped, carbon-coated vanadium oxide precursor with abundant oxygen vacancies (Cd0.015V2O3-x@C) using a straightforward one-pot thermal reduction method, followed by in-situ activation to form a high-performance cathode material, Cd0.004V2O5-y·nH2O@C. We find that the interlayered water dramatically reduces the electrostatic force between zinc ions and V2O5-y layers, meanwhile, abundant oxygen vacancies and cadmium doping alter the material’s band structure, resulting in enhanced electronic and ionic conductivities. Leveraging these advantages, the phase transitioned Cd0.004V2O5-y·nH2O@C cathode delivers a remarkably high capacity of 420 mAh/g (0.2 A/g), an excellent rate capability of 198 mAh/g (20.0 A/g), and an outstanding capacity retention of 78.5 % after 3500 cycles (20 A/g). This synergistic structure modification strategy of elemental doping and in-situ activation offers a novel approach to design high-performance vanadium oxide-based cathodes for advanced aqueous batteries.

High‐performance vanadium oxide‐based aqueous zinc batteries: Organic molecule modification, challenges, and future prospects

AbstractAqueous Zn‐vanadium batteries have been attracting significant interest due to the high theoretical capacity, diverse crystalline structures, and cost‐effectiveness of vanadium oxide cathodes. Despite these advantages, challenges such as low redox potential, sluggish reaction kinetics, and vanadium dissolution lead to inferior energy density and unsatisfactory lifespan of vanadium oxide cathodes. Addressing these issues, given the abundant redox groups and flexible structures in organic compounds, this study comprehensively reviews the latest developments of organic‐modified vanadium‐based oxide strategies, especially organic interfacial modification, and pre‐intercalation. The review presents detailed analyses of the energy storage mechanism and multiple electron transfer reactions that contribute to enhanced battery performance, including boosted redox kinetics, higher energy density, and broadened lifespan. Furthermore, the review emphasizes the necessity of in situ characterization and theoretical calculation techniques for the further investigation of appropriate organic “guest” materials and matched redox couples in the organic‐vanadium oxide hybrids with muti‐energy storage mechanisms. The review also highlights strategies for Zn anode protection and electrolyte solvation regulation, which are critical for developing advanced Zn‐vanadium battery systems suitable for large‐scale energy storage applications.

Electrospun carbon/iron–vanadium oxide nanofibers for high energy density supercapacitors

Highly flexible and conductive carbon nanofibers (CNFs) embedded with pseudocapacitive iron–vanadium oxide (FVO) nanoparticles were fabricated via electrospinning of a metal salt/polyacrylonitrile solution followed by high-temperature annealing (750 °C). CNFs have a graphitic structure with defects, which could accelerate electron mobility and the access of electrolytic ions to the multivalent FVO nanoparticles, respectively. Poly(methyl methacrylate) (PMMA) was introduced as a sacrificial polymer to alter the internal structure of the nanofibers and thus enhance the electrolytic ion transport pathways. Terephthalic acid was added to provide flexibility by increasing the cross-linking within the electrospun fibers. The flexible FVO/CNFs exhibited excellent electrochemical performance. The optimal sample had a high areal capacitance of 1058 mF·cm−2 at a current density of 2.5 mA·cm−2 and showed 100 % capacitance retention during long-term cycling (10,000 cycles). The capacitance at a high current density of 25 mA·cm−2 was 81.3 % of that at a current density of 2.5 mA·cm−2. Using a wider potential window of 0–1.6 V increased the energy density to 389 μW·h·cm−2. The optimal FVO/CNF sample maintained 90 % of its initial capacitance after 200 bending cycles.

Self-Standing vanadium oxide pillared carbon microfiber film as an excellent anode for lithium & sodium ion batteries

Insertion of substances (such as atoms/molecules/ions) into the interlayer spaces of graphite to increase its layer separation is found to be extremely useful for sodium-ion batteries (SIBs). Therefore, expanded graphitic systems are the obvious choice as anode material for both lithium/sodium-ion batteries (LIBs/SIBs). Hard carbon-based materials altogether give a decent electrochemical performance, as well as allow structural integrity for long-term use. Herein, we report a facile route to prepare free-standing vanadium oxide doped carbon microfibers (V@CMFs) films. The V@CMFs show ∼ 200 % expansion in the graphitic interlayer distances while accommodating minute deformations in the final compound which is further theoretically verified as the stage-1 type dilute graphite intercalation compound (GICs) with pillar-like structures. Best battery performance was obtained for the 1 % doped (V1@CMFs) sample, with an initial discharge capacity of 1501.8 and 703.4 mAhg−1, reversible capacities of 1253.8 and 288.7 mAhg−1 at 20 mAg−1, and rate capabilities i.e., 362.4 and 108.1 mAhg−1 at 1600 mAg−1, for LIBs and SIBs, respectively. The results revealed that the rate capability and the reversible specific capacity of the 1 % vanadium oxide doped carbon microfibers (V1@CMFs) are significantly superior compared to the pristine and previous reports. Here, the incorporation of just 1 % vanadium oxide acts as a pillar, enhancing the stability and conductivity of the carbon. Thus, the present work highlights the utility of molecularly doped GICs as potential anode materials for LIBs/SIBs.

Graphene-assisted improve electrochemical performance of manganese vanadium oxide for aqueous zinc-ion battery

Layer spacing of vanadium oxide can be effectively expanded by metal ion, however, its conductivity and electrochemical kinetics still require improvement. This work expands the layer spacing using manganese ion and help to improve conductivity and electrochemical kinetics by graphene. The results demonstrate that the layer spacing can be adjusted from 12.1 Å for pristine vanadium oxide (VOH) to 13.6 Å for manganese vanadium oxide (MnVO). Due to graphene introduction, it decreases to 11.6 Å for manganese vanadium oxide/graphene composite (MnVO-0.05–8/GN-15). Notably, the optimized composite delivers higher specific capacity of 507.5 mAh g−1 for MnVO-0.05–8/GN-15 than that of MnVO (410.4 mAh g−1) and VOH (370.1 mAh g−1) at current density of 0.5 A g−1. Furthermore, the MnVO-0.05–8/GN-15 exhibits fast Zn2+ ion diffusion ability, achieving high energy density of 403.51 Wh kg−1 and retaining an excellent cycle stability of 85.7% after 2000 cycles at a current density of 3 A g−1.

Charged organic ligands inserting/supporting the nanolayer spacing of vanadium oxides for high-stability/efficiency zinc-ion batteries.

Given their high safety, environmental friendliness and low cost, aqueous zinc-ion batteries (AZIBs) have the potential for high-performance energy storage. However, issues with the structural stability and electrochemical kinetics during discharge/charge limit the development of AZIBs. In this study, vanadium oxide electrodes with organic molecular intercalation were designed based on intercalating 11 kinds of charged organic carboxylic acid ligands between 2D layers to regulate the interlayer spacing. The negatively charged carboxylic acid group can neutralize Zn2+, reduce electrostatic repulsion and enhance electrochemical kinetics. The intercalated organic molecules increased the interlayer spacing. Among them, the 0.028EDTA · 0.28NH4 + · V2O5 · 0.069H2O was employed as the cathode with a high specific capacity (464.6mAhg-1 at 0.5Ag-1) and excellent rate performance (324.4mAhg-1 at 10Ag-1). Even at a current density of 20Ag-1, the specific capacity after 2000 charge/discharge cycles was 215.2mAhg-1 (capacity retention of 78%). The results of this study demonstrate that modulation of the electrostatic repulsion and interlayer spacing through the intercalation of organic ligands can enhance the properties of vanadium-based materials.

A simulation investigation of barium phosphate glasses enhanced with vanadium and tellurium ions for X- and gamma energies attenuation

Barium phosphate glass with fixed barium oxide (BaO) at 40 mol% and vanadium oxide (V2O5) at 1 mol% was successfully synthesized by the melt quenching process. Different concentrations of tellurium oxide (TeO2) were introduced at the expense of the phosphate groups (P2O5) to improve and modify the elastic and radiation shielding properties. The elastic parameters were calculated from the Makishima-Mackenzie model. The radiation shielding parameters were simulated and studied using the XCOM database to check the availability of such glass to withstand the X-ray and gamma energies.

Atomic Layer Deposition Synthesis of thin Films of Vanadium Oxides in a Reducing Hydrogen Atmosphere

Atomic Layer Deposition Synthesis of thin Films of Vanadium Oxides in a Reducing Hydrogen Atmosphere

Maximization of Micractinium sp., biomass and use of Dual-Purpose reduced graphene supported vanadium oxide nanoparticles for harvesting and subsequent biodiesel production

A sustainable media composition comprising of nanourea (NU), groundnut de-oiled cake (GDOC), and seaweed Extract (SE) was formulated using a mixture design for the cultivation of Micractinium sp. Maximum biomass yield and productivity of 5.52 ± 0.09 g/L and 0.72 ± 0.03 g/L d−1 were observed at 1.67 mM NU, 0.134 g/L GDOC and 0.250 mL L−1 SE, respectively. The highest lipid yield of 2.73 ± 0.24 g/L was also observed, respectively. The reduced graphene-supported vanadium oxide nanoparticles (RGO-VNPs) with a net surface charge of + 34.10 mV were developed, which acted as a % as well as a catalyst for transesterification. A maximum flocculation efficiency of 98 % was observed with 200 ppm of RGO-VNPs. The Fatty Acid Methyl Ester (FAME) yield of 96.81 ± 1.61 % was observed. Thus, the present study could provide a plausible solution for one-pot harvesting and synthesis of biodiesel utilizing microalgal lipids.

Ultra-thin V2O5 nanowires: synthesis and gas sensing characteristics

This study presents the synthesis of vanadium oxide nanowires via a simple hydrothermal method and explores their potential as high-performance sensors for monitoring harmful gases, with a particular focus on NO2. The microstructure and morphology of the nanowires were characterized using scanning electron microscopy, powder x-ray diffraction, and Raman spectroscopy. The vanadium oxide nanowire material demonstrates outstanding NO2 gas sensing capabilities, detecting 5 ppm with a rapid response and high sensitivity at an optimal working temperature of 150 °C. It exhibits a relative resistance change of 70%, showcasing a sub-ppm detection limit. The V2O5 nanowires exhibited good stability and high gas selectivity for NO2 over other interfering gases (H2S, NH3, C2H4, and CO). The ultrathin structure of the nanowires holds promise for practical applications in developing NO2 gas sensors. The study sheds light on the superior sensitivity of the V2O5 gas sensor toward NO2 at low temperatures, emphasizing the influence of the 1D structure on the sensing mechanism.

Enhanced dynamics of Al3+/H+ ions in aqueous aluminum ion batteries: Construction of metastable structures in vanadium pentoxide upon oxygen vacancies

In recent years, aqueous aluminum ion batteries have been widely studied owing to their abundant energy storage and high theoretical capacity. An in-depth study of vanadium oxide materials is necessary to address the precipitation of insoluble products covered cathode surface and the slow reaction kinetics. Therefore, a method using a simple one-step hydrothermal preparation and oxalic acid to regulate oxygen vacancies has been reported. A high starting capacity (400 mAh g−1) can be achieved by Ov-V2O5, and it is capable of undergoing 200 cycles at 0.4 A g−1, with a termination discharge capacity of 103 mAh g−1. Mechanism analysis demonstrated that metastable structures (AlxV2O5 and HxV2O5) were constructed through the insertion of Al3+/H+ during discharging, which existed in the lattice intercalation with V2O5. The incorporation of oxygen vacancies lowers the reaction energy barrier while improving the ion transport efficiency. In addition, the metastable structure allows the electrostatic interaction between Al3+ and the main backbone to establish protection and optimize the transport channel. In parallel, this work exploits ex-situ characterization and DFT to obtain a profound insight into the instrumental effect of oxygen vacancies in the construction of metastable structures during in-situ electrochemical activation, with a view to better understanding the mechanism of the synergistic participation of Al3+ and H+ in the reaction. This work not only reports a method for cathode materials to modulate oxygen vacancies, but also lays the foundation for a deeper understanding of the metastable structure of vanadium oxides.

Bimetallic ions pre-intercalated hydrated vanadium oxides for high-performance aqueous zinc-ion batteries

A new generation of rechargeable batteries known as Aqueous Zinc-Ion Batteries (AZIB) offers benefits including affordability, eco-friendliness, dependability, and safety. Hydrated vanadium oxides (V2O5·nH2O) show potential as cathodes for AZIB due to their layered structure and multivalent properties. However, the zinc storage performance is limited by the structural instability and slow zinc ion mobility. In this work, TiK-VOH (the bimetallic ions system of Ti4+ and K+ co-pre-intercalated in V2O5·nH2O) with lamellar fish scale-like structure is synthesized using a simple sol-gel method. The high positive charge density of the tetravalent Ti4+ is more beneficial to attract the electrons in the V-O layer and regulate the layer spacing (12.1 Å), which not only improves the diffusion kinetics of zinc ions, but also acts as a pillar to stabilize the layer structure. K+ mainly plays the role of improving electrical conductivity, and then accelerates the charge transfer in the electrode reaction process. Auxiliary density functional theory simulation further confirms that the diffusion energy barrier and Fermi level are optimized by pre-intercalating bimetallic ions. Based on the synergistic effect of Ti4+ and K+, the TiK-VOH material shows excellent zinc storage performance, the highest specific capacity of TiK-VOH reaches 393.4 mAh g−1 at a current density of 0.2 A g−1, even at 10 A g−1 (increased by 20 times), it still maintains a discharge specific capacity of 202 mAh g−1 with a capacity retention rate of 94 % after 2000 cycles, the overall performance is much better than the Ti-VOH and K-VOH. This work offers an alternative perspective for the modification of vanadium-based cathode of AZIBs.

Thermochromic properties and surface chemical states of reactive magnetron sputtered vanadium oxide thin films at various deposition pressures

Vanadium oxide thin films were prepared using reactive magnetron sputtering method, varying the deposition pressures from 4 to 10 mTorr while maintaining the other sputtering parameters constant. Our investigations revealed sensitive dependence of deposition pressure, chemical states of the V and O atoms, crystal phases, and thermochromic (TC) optical modulation. Specifically, the film deposited at 8 mTorr displayed distinct TC characteristics with a prevalent monoclinic m-VO2 phase according to X-ray diffraction (XRD), supported by X-ray photoelectron spectroscopy (XPS). Optical transmittance modulation and electrical property measurements revealed a metal–insulator transition (MIT), confirming the intimate connection between TC characteristics and presence of the m-VO2 phase. Films deposited at pressures lower or higher than 8 mTorr exhibited typical semiconductor behavior without TC characteristics, further supported by in situ XRD, where (110) plane shifted to lower angle upon heating above τC. Chemical state analysis by XPS revealed a clear correlation between V−O peaks and the presence of a VO2 phase, with the film deposited at 8 mTorr displaying relatively large peak fitted area indicative of the VO2 phase. These findings highlight the critical and sensitive dependence of the deposition conditions in tailoring the properties of vanadium oxide thin films and provide valuable insights for potential applications in chromogenic films.

Synergistic Regulation of Anode and Cathode Interphases via an Alum Electrolyte Additive for High-Performance Aqueous Zinc-Vanadium Batteries.

A zinc (Zn) metal anode paired with a vanadium oxide (VOx) cathode is a promising system for aqueous Zn-ion batteries (AZIBs); however, side reactions proliferating on the Zn anode surface and the infinite dissolution of the VOx cathode destabilise the battery system. Here, we introduce a multi-functional additive into the ZnSO4 (ZS) electrolyte, KAl(SO4)2 (KASO), to synchronise the in situ construction of the protective layer on the surface of the Zn anode and the VOx cathode. Theoretical calculations and synchrotron radiation have verified that the high-valence Al3+ plays dual roles of competing with Zn2+ for solvation and forming a Zn-Al alloy layer with a homogeneous electric field on the anode surface to mitigate the side reactions and dendrite generation. The Al-containing cathode-electrolyte interface (CEI) considerably alleviates the irreversible dissolution of the VOx cathode and the accumulation of byproducts. Consequently, the Zn||Zn cell with KASO exhibits an ultra-long cycle of 6000 h at 2 mA cm-2. Importantly, the VOx cathodes (VO2, V2O5 and NH4V4O10) in the ZS-KASO electrolyte showed excellent cycling stability, including Zn powder||VO2 cells and Zn||VO2 pouch cells. Even better, the full cell exhibits excellent cycling stability at low negative/positive (N/P) ratio of 2.83 and high mass loading (~16 mg cm-2). This study offers a straightforward and practical reference for concurrently addressing challenges at the anode and cathode of AZIBs.

VO2·xH2O nanoribbons as high-capacity cathode material for aqueous zinc-ion batteries: Electrolyte selection and performance optimization

In the pursuit of efficient energy storage solutions for renewable energy, aqueous zinc-ion batteries (ZIBs) have emerged as promising contenders, offering high capacity and manufacturability. Among transition metal oxides, vanadium dioxide (VO2) stands out as the synergestic behavior of H+ and Zn2+ ions with the VO2·xH2O ensures high specific capacity in Zn-ion based battery. Here, we present the successful synthesis of hydrated vanadium oxide (VO2·xH2O) nanoribbons via the hydrothermal method, followed by comprehensive characterizations to assess material properties. A systematic study on electrolyte selection, focusing on achieving high capacity and stability, was conducted using varying electrolyte types and concentrations. The superior 3 M Zn(CF3SO3)2 electrolyte was chosen for further electrochemical investigations, leading to the formation of a two-electrode system comprising VO2·xH2O//Zn half-cell ZIB, which lasts more than 1000 cycles at 1 A g−1 in addition to capacity retention of 82.18% while providing a capacity of 235.63 mAh g−1 at 0.1 A g−1, while demonstrating favorable rate capability. Ex-situ XRD analysis unveiled insights into the designed ZIB's charging/discharging mechanism, showcasing variations in cathode crystallinity and the formation of Zn(OH)2 peaks during cycling. To establish the effective usage of this formed ZIB for daily-life applications, the coin cell was effectively used to power an LED and LCD screen, and the subsequently attained value of capacity was compared along with the available literature. This work surpasses existing ZIBs in terms of capacity and cyclability, paving the way for a more sustainable future through efficient energy storage from renewable sources.