V2O5 Electrode Research Articles

Ultralow-concentration electrolyte unlocking the high-stable proton storage in (NH4)0.5V2O5 electrode

High-concentration electrolytes have been proven to be an effective strategy to improve the electrochemical performance of aqueous batteries. However, dramatically increasing the salt concentration will leads to high cost, high viscosity, and low conductivity. Here, we propose an ultralow-low concentration electrolyte of 1 mM H2SO4 solution for the practical application of aqueous batteries for the first time. Surprisingly, the (NH4)0.5V2O5 (NVO) achieves good electrochemical performance benefitting from the special Grotthuss mechanism of proton and structural stability of electrode material in dilute acidic electrolyte. The NVO electrode exhibits a high reversible capacity of about 150 mAh g−1 at a low current density of 50 mA g−1 and impressive capacity retention of 80% over 70,000 cycles at 2 A g−1. The low concentration electrolyte chemistry will open a novel route for the exploitation of durable and low-cost aqueous batteries.

Applied IrO2 Buffer Layer as a Great Promoter on Ti-Doping V2O5 Electrode to Enhance Electrochromic Device Properties.

Electrochromic devices (ECDs) are a promising material for smart windows that are capable of transmittance variation. However, ECDs are still too expensive to achieve a wide market reach. Reducing fabrication cost remains a challenge. In this study, we inserted an IrO2 buffer layer on Ti-doped V2O5 (Ti:V2O5) as a counter electrode using various Ar/O2 gas flow ratios (1/2, 1/2.5, 1/3 and 1/3.5) in the fabrication process. The buffered-ECD resulted in a larger cyclic voltammetry (CV) area and the best surface average roughness (Ra = 3.91 nm) to promote electrochromic performance. It was fabricated using the low-cost, fast deposition process of vacuum cathodic arc plasma (CAP). This study investigates the influence of the IrO2 buffer/Ti:V2O5 electrode on ECD electrochemical and optical properties, in terms of color efficiency (CE) and cycle durability. The buffered ECD (glass/ITO/WO3/liquid electrolyte/IrO2 buffer/Ti:V2O5/ITO/glass) demonstrated excellent optical transmittance modulation; ∆T = 57% (from Tbleaching (67%) to Tcoloring (10%)) at 633 nm, which was higher than without the buffer (ITO/WO3/liquid electrolyte/Ti:V2O5/ITO) (∆T = 36%). In addition, by means of an IrO2 buffer, the ECD exhibited high coloration efficiency of 96.1 cm2/mC and good durability, which decayed by only 2% after 1000 cycles.

Tailoring Electrodes and Electrolytes in Emerging Aqueous Ammonium-Ion Batteries for Enhanced Performance

The lithium ion battery, a most popular battery technology powering much of our digital and mobile lifestyle, has posed limitations for wider future use, mainly because of concerns raised over their cost, safety, and environmental impact. Most of these concerns come from its use of organic electrolytes that are viscous, flammable, and toxic, as well as the high price of lithium due to the limited lithium sources. Hence, tremendous research efforts have been devoted to the study of aqueous electrolytes, attributed to its being safe, convenient, inexpensive, more durable and less prone to thermal runaways. Its higher ionic conductivity combined with simplicity of the chemistry environment may facilitate long cycle life of the battery too. Moreover, non-metallic charge carriers such as ammonium (NH4 +) ions have attracted much attention, due to the following great merits: (i) favorable sustainability and nontoxicity as it could be synthesized from infinite or unlimited sources (nitrogen and hydrogen in air); (ii) a lighter mass of 18 mAh/g for high energy density batteries; (iii) the smallest hydration radius of 3.31 Å (despite its large ionic radius of 1.48 Å) leading to fast ion diffusion in the electrolyte; (iv) the nonmetallic interaction between NH4 + carriers and host materials (e.g., hydrogen bond) is more flexible than the rigid metal coordination; (v) nondiffusion-controlled topochemistry between nonmetallic charging carriers and electrode framework during insertion/extraction process leading to pseudo-capacitive-dominated behavior and thus ultrafast kinetics. Nevertheless, a challenge associated with the development of high-performance ammonium ion batteries (AIBs) is that the large ionic radius of NH4 + requires host materials with larger interlayer spacing or open structure for accommodation and thus limits the choice of electrode materials.In this work, we employ facile solution processing methods to synthesize various nanostructured electrode materials ranging from oxides to polymer and composite to improve the electrochemical performance of AIBs. Examples include ammonium vanadate, vanadium oxide, polyaniline, and composite consisting of vanadium oxide and polyaniline. For example, a facile in-situ intercalation approach is utilized to prepare a composite material with polyaniline (PANI) intercalated in the interlayers of hydrated V2O5, for application as the electrode in high-performance AIBs. It is found that the interlayer spacing of hydrated V2O5 is expanded to 13.99Å, offering wide channels to accommodate NH4 + ions during intercalation/deintercalation processes. The resulted AIB exhibits a high capacity of 192.5 mAh/gwhen cycled at a specific current of 1 A/g and retains 39 mAh/g at an extremely specific current of 20 A/g, together with stable cycle life. The diffusion kinetics of the NH4 + ions, influenced by the hydrogen bonds formed between NH4 + ion and O2- in the host structure, is effectively enhanced by the unique π-conjugated structure of PANI, leading to high capacity, improved rate capability and improved cycle life of AIBs. This PANI-intercalated V2O5 (PVO) electrode material demonstrates stable and ultrafast NH4 + ion storage, as revealed by X-ray and Raman spectroscopy characterizations. The performance of AIBs can be further maximized by optimizing the composition of PVO electrodes or the ratio between PANI and hydrated vanadium oxide. Additionally, different aqueous liquid-state electrolytes and hydrogel electrolytes with composition tuned are tested in AIBs, for enhanced cycleability and stability of the batteries. As such, this study opens a new horizon by developing various electrode/electrolyte materials to boost the performance of aqueous ammonium-ion batteries that have great potential for next-generation safe and low-cost electrochemical energy storage.

Metal-Organic Framework Fabricated V2O5 Cathode Material for High-Performance Lithium-Ion Batteries

In this article, oval-shaped V2O5 nanoparticles were hydrothermally synthesized using a metal-organic framework (MOF), which was then followed by calcination under an air atmosphere. The obtained sample was characterized through various characterization techniques to determine the sample purity and the structural and morphological details. Since V2O5 possesses a layered crystal structure, it exhibits promising electrochemical performances as a cathode material for lithium-ion battery applications. However, poor cycling and inferior rate capabilities are the major issues that limit its application. Thus, a strategy to fabricate unique oval-shaped V2O5 nanoparticles was employed here to improve electrochemical performances using an MOF, which acts as a template and provides a skeleton for the growth of a novel nanostructure. It is believed that the oval-shaped morphology is beneficial to achieving better electrochemical results due to the large surface area and the existence of numerous channels for lithiation and de-lithiation. The obtained electrochemical result reveals that the V2O5 electrode can be considered a prominent cathode material for next-generation lithium-ion battery applications.

Improving the Li Ion Storage Capability of V2o5 Electrode by Using Aminoalkyldisiloxane Electrolyte Additive

Improving the Li Ion Storage Capability of V2o5 Electrode by Using Aminoalkyldisiloxane Electrolyte Additive

Effective pseudocapacitive performance of binder free transparent α-V2O5 thin film electrode: Electrochemical and some surface probing

Vanadium oxide nanomaterial was successfully prepared on conductive substrate via a simple and facile chemical route with no binder or additive. The film was characterized to investigate its microstructural, optical, electrical and electrochemical properties. The SEM micrographs of the annealed film presented enabling environment that is required for effective photocatalysis. It also demonstrated enhanced interaction between the film and the substrate and adequate pore size distribution that can allow free electrolytic ion intercalation/deintercalation for efficient supercapacitive response. EDX confirmed the elemental composition of the film. XRD and Raman spectroscopy showed substantial characteristic peaks that are attributes of orthorhombic crystal structure of V2O5 powder. Optical studies showed that the film exhibited high visible light transmittance and its energy band gap was found to be 2.77 eV. Pseudocapacitive performance of the V2O5 electrode was investigated via a three-electrode cell configuration. The film electrode exhibited highest areal capacity of 1.18 μAh cm−2, energy density of 0.485 μWhcm−2 at a power density of 107.71 μWcm−2 and current density 0.25 mAcm−2, moderate charge transfer resistance and superior cycling stability. The study demonstrated the viability of V2O5 film as electrode material for the development of high-performance supercapacitors.

In operando study of orthorhombic V2O5 as positive electrode materials for K-ion batteries

Herein, the electrochemical performance and the mechanism of potassium insertion/deinsertion in orthorhombic V2O5 nanoparticles are studied. The V2O5 electrode displays an initial potassiation/depotassiation capacity of 200 mAh g−1/217 mAh g−1 in the voltage range 1.5–4.0 V vs. K+/K at C/12 rate, suggesting fast kinetics for potassium insertion/deinsertion. However, the capacity quickly fades during cycling, reaching 54 mAh g−1 at the 31st cycle. Afterwards, the capacity slowly increases up to 80 mAh g−1 at the 200th cycle. The storage mechanism upon K ions insertion into V2O5 is elucidated. In operando synchrotron diffraction reveals that V2O5 first undergoes a solid solution to form K0.6V2O5 phase and then, upon further K ions insertion, it reveals coexistence of a solid solution and a two-phase reaction. During K ions deinsertion, the coexistence of solid solution and the two-phase reaction is identified together with an irreversible process. In operando XAS confirms the reduction/oxidation of vanadium during the K insertion/extraction with some irreversible contributions. This is consistent with the results obtained from synchrotron diffraction, ex situ Raman, X-ray photoelectron spectroscopy (XPS), and transmission electron microscopy (TEM). Moreover, ex situ XPS confirms the “cathode electrolyte interphase” (CEI) formation on the electrode and the decomposition of CEI film during cycling.

RGO-encapsulated Sn-doped V2O5 nanorods for high-performance Supercapacitors

Reduced graphene oxide (rGO) anchored Sn doped V2O5 (Sn-V2O5/rGO) nanocomposite materials are produced by employing the sol-gel method. The Sn-V2O5/rGO nanocomposite is composed of Sn dopant homogeneously dispersed on V2O5 nanorods and rGO nanosheets. At the time of charge/discharge process, this peculiar structure mainly reduces the amount of Na+ inflation, enhances the electrolyte insertion into the electrode and also increases the conductivity of the Sn doped V2O5 electrode. As results, the Sn-V2O5/rGO, 4%Sn-V2O5 and V2O5 electrodes exhibits excellent electrochemical performance and it provides high reversible specific capacitance of about 159.37, 139.06 and 120.10 F g−1 at 1 Ag−1. Even at this high current density, this Sn-V2O5/rGO electrode also withstands the capacitance maximum of about 73 %. Concretely, the prepared Sn-V2O5/rGO electrode material exhibits the low charge transfer resistivity than 4%Sn-V2O5 and V2O5 electrodes. Moreover, the electrode obeys the excellent capacitance retention (95 %) at 5 Ag−1 for the 1000th cycle.

In-situ formation of uniform V2O5 nanocuboid from V2C MXene as electrodes for capacitive deionization with higher structural stability and ion diffusion ability

Capacitive desalination (CDI) has aroused much attention due to its advantages of low energy consumption and environmental compatibility. However, typical CDI processes display limited efficiency. In this work, one-dimensional V2O5 with nanocuboid structure was prepared with MXenes(V2C) precursor for the first time, which has high adsorption capacity, structure stability and fast ion diffusion ability. The as-synthesized V2O5 electrode achieved a salt adsorption capacity(SAC) of 55.2 mg NaCl g−1 V2O5 under optimized conditions with a constant current density of 30 mA g−1, a voltage range from −0.6 to 1.2 V, and an initial solution of 500 mg L−1 NaCl. Furthermore, from the comprehensive analysis of mechanism, due to the high conductivity and low charge transfer resistance of V2O5 electrode, it reduces the energy loss of the resistance during desalination. A particularly low energy consumption of 0.27 kWh kg−1-NaCl is reached when the operation is carried out successfully at low voltage range, indicating the advantages of energy saving and high efficiency. Therefore, V2O5 is an attractive and promising electrode material, which exhibits the potential of pseudocapacitive materials with certain structure for practical CDI application in future and inspires us to have a deep insight into the effect of morphology on the properties.

Enhancement of Electrochemical Performance of All-Solid-State Lithium‐Ion Thin-Film Batteries By Interface Modification with Al2O3 Interlayer

IntroductionAll-solid-state lithium-ion thin-film battery is one of the promising candidates for next-generation battery systems. However, the low Li-ion conductivity of solid electrolytes and the considerable electrolyte/electrode interface resistance greatly hamper the commercialization of all-solid-state thin-film Li-ion batteries. In this study, we fabricate the all-solid-state lithium-ion thin-film battery using V2O5 electrode and LiPON solid electrolyte. And we introduce Al2O3 interlayer between the Li metal and LiPON solid electrolyte to decrease the interfacial resistance.ExperimentalThe Cathode (V2O5), the solid electrolyte (LiPON) and the interlayer (Al2O3) were prepared on Ti/Pt-coated Si substrates by RF sputtering system. In addition, The Li anode and the Cu current collector were deposited by thermal evaporation. The thicknesses of the V2O5 and LiPON thin films were approximately 100 and 500 nm, respectively. To evaluate the electrochemical properties, 2032-type coin cells were assembled in an argon-filled glove box. Charge/Discharge tests were carried out at various C rates from 0.5 to 100 C with cutoff voltages of 2 and 4 V. Electrochemical impedance spectroscopy was conducted in the frequency range of 100 KHz – 1 Hz with a sinus amplitude voltage of 10 mV.Results and DiscussionThe XRD results of the V2O5 and LiPON thin film shows the amorphous structure. The Charge/Discharge profiles shows typical curves of amorphous V2O5 electrode. The rate capability results show that the insertion of Al2O3 interlayer between the Li metal and the LiPON solid electrolyte sample enhanced the rate performance. Also, The TEM cross-section image results demonstrate that Al2O3 interlayer improves the adhesion to Li metal on LiPON solid electrolyte. These results indicate that as the adhesion between Li metal and LiPON solid electrolyte is improved, electrochemical performance is improved in all-solid-state lithium-ion thin-film batteries.ConclusionsWe successfully fabricated the all-solid-state lithium-ion thin-film battery using the amorphous V2O5 electrode and LiPON solid electrolyte. In addition, through the insertion of Al2O3, the interface between LiPON and Li became uniform and the electrochemical properties were improved. In other words, the interfacial control between solid electrolyte and Li metal is a key factor for the improvement of the electrochemical properties of all-solid-state lithium-ion thin-film batteries.

Cathode-Electrolyte Interphase in a LiTFSI/Tetraglyme Electrolyte Promoting the Cyclability of V2O5.

V2O5, one of the earliest intercalation-type cathode materials investigated as a Li+ host, is characterized by an extremely high theoretical capacity (441 mAh g–1). However, the fast capacity fading upon cycling in conventional carbonate-based electrolytes is an unresolved issue. Herein, we show that using a LiTFSI/tetraglyme (1:1 in mole ratio) electrolyte yields a highly enhanced cycling ability of V2O5 (from 20% capacity retention to 80% after 100 cycles at 50 mA g–1 within 1.5–4.0 V vs Li+/Li). The improved performance mostly originates from the V2O5 electrode itself, since refreshing the electrolyte and the lithium electrode of the cycled cells does not help in restoring the V2O5 electrode capacity. Electrochemical impedance spectroscopy (EIS), post-mortem scanning electron microscopy (SEM), energy-dispersive X-ray (EDX) spectroscopy, and X-ray photoelectron spectroscopy (XPS) have been employed to investigate the origin of the improved electrochemical behavior. The results demonstrate that the enhanced cyclability is a consequence of a thinner but more stable cathode–electrolyte interphase (CEI) layer formed in LiTFSI/tetraglyme with respect to the one occurring in 1 M LiPF6 in EC/DMC (1:1 in weight ratio, LP30). These results show that the cyclability of V2O5 can be effectively improved by simple electrolyte engineering. At the same time, the uncovered mechanism further reveals the vital role of the CEI on the cyclability of V2O5, which can be helpful for the performance optimization of vanadium-oxide-based batteries.

Enhanced electrochromic performance of carbon-coated V2O5 derived from a metal–organic framework

In this study we synthesized a vanadium (V)-containing metal–organic framework (MOF) and used it as a template to prepare V2O5 NPs. We used MIL-47, a V-containing MOF having uniform C and V distributions, as a precursor for the preparation of carbon-coated V2O5 (C@V2O5) samples through annealing. The C@V2O5 structures were readily dispersed in poly(3,4-ethylenedioxythiophene):polystyrenesulfonate (PEDOT:PSS) to form stable solutions, allowing the deposition of C@V2O5 on various substrates through simple low-temperature solution-based processes. The uniform coating of carbon on V2O5 was useful for two reasons: (i) the outer layer enhanced the electronic conductivity of a V2O5 electrode and its corresponding electrochemical properties and (ii) based on the electrochemical quartz crystal microbalance (EQCM) analysis, the carbon coating served as a buffer layer that allowed Li+ ion transport, but blocked migration of solvent into the V2O5 electrode, thereby improving the dimensional and electrochemical stability. Compared with the bare V2O5, C@V2O5 exhibited excellent electrochromic (EC) performance, with an EC contrast of 45.8%, a mean response time of 3.4 s, and a coloration efficiency of 89.3 cm2/C. C@V2O5 also displayed higher cycling stability (80.6% retention after 5000 cycles) and highly reversible ionic transport during redox reactions, compared with those of the bare V2O5.

Aluminium pre-intercalated orthorhombic V2O5 as high-performance cathode material for aqueous zinc-ion batteries

Rechargeable aqueous zinc-ion batteries (AZIBs) are emerging as promising candidates for large-scale energy storage systems because of their low cost and high safety. However, the slow migration rate and strong electrostatic repulsion of divalent Zn2+ put forward many requirements for the properties of cathode materials. Herein, we present an aluminium pre-intercalated orthorhombic V2O5 (Al0.2V2O5) as a new cathode material for AZIBs. The analyses of GITT, ex-situ XRD, TEM and XPS indicate that the Al0.2V2O5 electrode possesses a higher Zn2+ diffusion coefficient than V2O5. And, the pre-intercalated Al3+ can stabilize the crystal structure and prevent Zn2+ from being trapped in the lattice. Because of the above advantages, Al0.2V2O5 shows much-enhanced electrochemical performance including a high capacity of 448.4 mA h g−1 at 0.1 A g−1, excellent rate capability of 143.9 mA h g−1 at 10 A g−1 and impressive long-term cycling stability with a capacity retention of 61.4% after 5000 cycles at 5 A g−1. Furthermore, the Al0.2V2O5/Zn battery can provide a high energy density of 327.1 W h kg−1 at 0.1 A g−1 and a high power density of 5491.8 W kg−1 at 10 A g−1, which shows great potential in the applications of large-scale energy storage.

Tuning the supercapacitive performance of vanadium oxide electrode material by varying the precursor solution concentration

Well adherent spray deposited electrode material with excellent physical and electrochemical properties are fascinating for researchers across the world for their application in the energy storage field. In this context, cluster like vanadium oxide (V2O5) deposited on the stainless steel substrate by using spray pyrolysis technique. For this deposition, the solution concentration of Ammonium metavanadate precursor was varied from 10 mM to 100 mM. The precursor solution 40 ml was sprayed at a fixed deposition temperature of 673 K by the automatic spray pyrolysis technique. The influence of the precursor concentration on the structural, morphological, and electrochemical characteristics of the deposited electrode material was studied by using X-ray diffraction, scanning electron microscopy, transmission electron microscopy, cyclic voltammetry, chronopotentiometry, and electrochemical impedance spectroscopy analysis. The morphology of the obtained spray pyrolyzed V2O5 samples show spikes like grains. The V2O5 deposited samples show excellent supercapacitive properties, among that 70 mM precursor exhibits the absolute supercapacitive performance with the highest value of specific capacitance is 315 F/g at scan rate 5 mV/s, specific energy density 0.43 Wh/kg, specific power density 283.3 kW/kg and efficiency is 86.97%. Moreover, stability study shows 71% capacitance retention over 2000 cycles in 1 M KCl electrolyte. These results represent that the V2O5 electrode is the suitable electrode material and would be the most appropriate candidate for future energy storage applications.

Revealing the Intrinsic Origin for Performance-Enhancing V2O5 Electrode Materials.

Revealing the intrinsic origin is critical for developing performance-enhancing V2O5 battery-type electrode materials. In this work, ultralong single-crystal V2O5 wires (W-V2O5) and V2O5 plate particles (P-V2O5) with similar physicochemical properties were compared to investigate the possible stimulative factors for pseudocapacitive enhancement. Our results indicate that besides the most-discussed specific surface area (or nanostructure), the enhanced electronic conductivity, the controllable interlamellar spacing distance, and the ion-transporting route as intrinsic origin also greatly affect their pseudocapacitive enhancement. First, the ultralong single-crystal wire structure can apparently enhance the electrons transport; second, the unique [001] facet orientation along the wire direction enlarges the interlamellar spacing distance and shortens the Li+ inserting route, thus facilitating the redox reactions by providing fast channels for charge carrier intercalation. Thus W-V2O5 showed much higher capacitance, better rate, and cycling capability than those of P-V2O5. This new insight presented here provides guidance for the design of V2O5 electrode materials and opens new opportunities in the development of high-performance battery-type electrode materials.

Tuning the Kinetics of Zinc-Ion Insertion/Extraction in V2 O5 by In Situ Polyaniline Intercalation Enables Improved Aqueous Zinc-Ion Storage Performance.

Rechargeable zinc-ion batteries (ZIBs) are emerging as a promising alternative for Li-ion batteries. However, the developed cathodes suffer from sluggish Zn2+ diffusion kinetics, leading to poor rate capability and inadequate cycle life. Herein, an in situ polyaniline (PANI) intercalation strategy is developed to facilitate the Zn2+ (de)intercalation kinetics in V2 O5 . In this way, a remarkably enlarged interlayer distance (13.90 Å) can be constructed alternatively between the VO layers, offering expediting channels for facile Zn2+ diffusion. Importantly, the electrostatic interactions between the Zn2+ and the host O2- , which is another key factor in hindering the Zn2+ diffusion kinetics, can be effectively blocked by the unique π-conjugated structure of PANI. As a result, the PANI-intercalated V2 O5 exhibits a stable and highly reversible electrochemical reaction during repetitive Zn2+ insertion and extraction, as demonstrated by in situ synchrotron X-ray diffraction and Raman studies. Further first-principles calculations clearly reveal a remarkably lowered binding energy between Zn2+ and host O2- , which explains the favorable kinetics in PANI-intercalated V2 O5 . Benefitting from the above, the overall electrochemical performance of PANI-intercalated V2 O5 electrode is remarkable improved, exhibiting excellent high rate capability of 197.1 mAh g-1 at current density of 20 A g-1 with capacity retention of 97.6% over 2000 cycles.

Pillaring Effect of K Ion Anchoring for Stable V2O5‐Based Zinc‐Ion Battery Cathodes

AbstractAqueous zinc‐ion batteries (ZIBs) have attracted widespread attention due to their advantages in safety and environmental benignity. However, achieving a cathode material with stable electrochemical performance for such a system remains an ongoing challenge. Herein, a K0.5V2O5 cathode has been designed and synthesized by intercalating of K+ into V2O5, thus constructing a stable crystal structure by forming chemical bonds between V2O5 layers. The successful intercalation of K+ has been confirmed by a series of experimental tests and Vienna Ab‐initio Simulation Package simulation. These layer‐interlinking chemical bonds act as “pillars” to strongly hold the V2O5 layers together and protect them from dissolution. Furthermore, the K0.5V2O5 electrode also exhibits excellent durability (about 150 mA h g−1 at 5 A g−1 after 3000 cycles). More impressively, even after standing for three days in the solution of 3 M ZnSO4 electrolyte, the K0.5V2O5 electrode still maintains a high capacity of 92.2 mA h g−1 after 150 cycles, demonstrating its outstanding stability and tolerance in such aqueous electrolyte.

Coin cell fabricated symmetric supercapacitor device of two-steps synthesized V2O5 Nanorods

A highly efficient and effective nanostructured vanadium oxide (V2O5) compound was synthesized for supercapacitor applications. A facile two-step method comprising preheating activation, followed by a hydrothermal route was utilized to synthesize V2O5 nanorods. As an electrode, the V2O5 nanorods exhibited a high specific capacitance of 347 F g−1 at 1 A g−1. The remarkable cyclic stability of the V2O5 compound indicates adequate potential for the fabrication of a symmetric supercapacitor device. A coin-cell symmetric supercapacitor device assembled using the V2O5 electrode exhibited excellent electrochemical performance, including a specific capacitance of 172 F g−1, an energy density of 23.9 W h kg−1, a power density of 937 W kg−1, and capacitance retention of 94.3% after 10,000 cycles.

Highly reversible crystal transformation of anodized porous V2O5 nanostructures for wide potential window high-performance supercapacitors

The advancement of efficient pseudocapacitive electrodes is a formidable challenge. In this study, we fabricated a binder-free porous network of vertically aligned V2O5 nanochannels via the simple and economical electrochemical anodization of vanadium foil. Reversible charge storage and the structural transformation of V2O5 during successive reduction and oxidation cycles was confirmed through X-ray diffraction analysis. We used several electrochemical techniques to study pseudocapacitive charge storage within the active sites of the porous network and rapid charge transfer through the vertical V2O5 channels in a 1 M LiClO4–propylene carbonate electrolyte. The as-prepared V2O5 electrode was studied over a wide potential window of 1.5 V, and it exhibited a specific capacitance of 840 F g−1 at 4 A g−1. A rate capability of 48% was observed with an eight-fold increase in the current density, and the electrode retained 90% of its capacitance after 5500 CV cycles. This performance indicated that the porous structure was highly retained, as confirmed through microstructural analysis after cycling. The V2O5 electrode presented herein may provide new options for replacing electrodes in next-generation supercapacitors.

Structural characteristic of vanadium(V) oxide/sulfur composite cathode for magnesium battery applications

Abstract Magnesium batteries are regarded as promising candidates for energy storage devices owing to their high volumetric capacity. The practical application is hindered, however, by strong electrostatic interactions between Mg2+ and the host lattice and due to the formation of a passivation layer between anode and electrolyte. V2O5 is a typical intercalation compound with a layered crystal structure ((0 0 1) interlayer spacing ~ 11.53 Å), which can act as a good host for the reversible insertion and extraction of multivalent cations. Herein, we have presented an investigation of the effects of S injection on the structure, electrochemical performance and Mg2+ diffusion in V2O5 cathode materials for Mg-ion batteries. The V2O5/S composite structure was investigated using X-ray diffraction, field-emission scanning electron microscope and energy dispersive X-ray spectroscopy. The integrated electrode exhibits an improvement in the electrical and electrochemical properties compared to the V2O5 electrode. The as-prepared V2O5/S composite has an initial discharge capacity of 310 mAh g−1 compared to 160 mAh g−1 for the V2O5 electrode. The V2O5/S composite is a promising cathode material for magnesium-ion battery applications.