Vanadium Bronze Research Articles

Interlayer expanded magnesium vanadium bronze for high capacity stable aqueous zinc batteries and method for proton contribution calculation

Magnesium vanadium bronze, MgV6O16·6H2O, is demonstrated as a cathode material for aqueous zinc batteries. Its remarkable electrochemical performance is attributed to the hydrated magnesium pillar layer, which enhances zinc ion diffusion into the structure, yielding a high initial discharge capacity of 298 mAh g−1 and capacity retention above 97 % after 300 cycles. Zinc ions and protons are co-intercalated into the MgV6O16·6H2O structure, while zinc hydroxide sulfate forms on the surface during the discharge process. Ex-situ X-ray diffraction results and elemental analyses confirm the zinc and proton co-intercalation reaction within the MgV6O16·6H2O structure during cycling, providing detailed insights into the electrochemical mechanisms. These findings demonstrate the potential of MgV6O16·6H2O as a high-energy cathode material for aqueous zinc batteries and offer a comprehensive understanding of the zinc ion and proton co-intercalation mechanism in the MgV6O16·6H2O structure.

Intercalated PtCo Electrocatalyst of Vanadium Metal Oxide Increases Charge Density to Facilitate Hydrogen Evolution.

Efforts to develop high-performance electrocatalysts for the hydrogen evolution reaction (HER) are of utmost importance in ensuring sustainable hydrogen production. The controllable fabrication of inexpensive, durable, and high-efficient HER catalysts still remains a great challenge. Herein, we introduce a universal strategy aiming to achieve rapid synthesis of highly active hydrogen evolution catalysts using a controllable hydrogen insertion method and solvothermal process. Hydrogen vanadium bronze HxV2O5 was obtained through controlling the ethanol reaction rate in the oxidization process of hydrogen peroxide. Subsequently, the intermetallic PtCoVO supported on two-dimensional graphitic carbon nitride (g-C3N4) nanosheets was prepared by a solvothermal method at the oil/water interface. In terms of HER performance, PtCoVO/g-C3N4 demonstrates superior characteristics compared to PtCo/g-C3N4 and PtCoV/g-C3N4. This superiority can be attributed to the notable influence of oxygen vacancies in HxV2O5 on the electrical properties of the catalyst. By adjusting the relative proportions of metal atoms in the PtCoVO/g-C3N4 nanomaterials, the PtCoVO/g-C3N4 nanocomposites show significant HER overpotential of η10 = 92 mV, a Tafel slope of 65.21 mV dec-1, and outstanding stability (a continuous test lasting 48 h). The nanoarchitecture of a g-C3N4-supported PtCoVO nanoalloy catalyst exhibits exceptional resistance to nanoparticle migration and corrosion, owing to the strong interaction between the metal nanoparticles and the g-C3N4 support. Pt, Co, and V simultaneous doping has been shown by Density Functional Theory (DFT) calculations to enhance the density of states (DOS) at the Fermi level. This augmentation leads to a higher charge density and a reduction in the adsorption energy of intermediates.

Controlling Electron Delocalization in Vanadium‐Based Hybrid Bronzes through Molecular Templation

AbstractWe show that the conductivity of hybrid vanadium bronzes—mixed‐valence organic–inorganic vanadium oxides—can be tuned over six orders of magnitude through judicious choice of molecular component. By systematically varying the steric profile, charge density, and propensity to hydrogen bond across a series of eight diammonium‐based molecules, we engender multiple distinct motifs of V−O connectivity within the two‐dimensional vanadium oxide layers of a family of bulk crystalline hybrid materials. A combination of single‐crystal and powder X‐ray diffraction analysis, variable‐temperature electrical transport measurements, and a range of spectroscopic methods, including UV/Visible diffuse reflectance, X‐ray photoelectron, and electron paramagnetic resonance are employed to probe how vanadium oxide layer topology correlates with electron localization. Specifically, alkylammonium molecules yield hybrids featuring more corrugated layers that contain V−O tetrahedra as well as a higher ratio of corner‐sharing to edge‐sharing polyhedra and that exhibit highly localized electronic behavior, while alkyl bipyridinium molecules yield more regular layers with polyhedral edge‐sharing that show substantially delocalized electronic behavior. This work allows for the development of design principles based on structure–property relationships and brings the charge transport capabilities of hybrid vanadium bronzes to more technologically relevant levels.

Controlling Electron Delocalization in Vanadium-Based Hybrid Bronzes through Molecular Templation.

We show that the conductivity of hybrid vanadium bronzes-mixed-valence organic-inorganic vanadium oxides-can be tuned over six orders of magnitude through judicious choice of molecular component. By systematically varying the steric profile, charge density, and propensity to hydrogen bond across a series of eight diammonium-based molecules, we engender multiple distinct motifs of V-O connectivity within the two-dimensional vanadium oxide layers of a family of bulk crystalline hybrid materials. A combination of single-crystal and powder X-ray diffraction analysis, variable-temperature electrical transport measurements, and a range of spectroscopic methods, including UV/Visible diffuse reflectance, X-ray photoelectron, and electron paramagnetic resonance are employed to probe how vanadium oxide layer topology correlates with electron localization. Specifically, alkylammonium molecules yield hybrids featuring more corrugated layers that contain V-O tetrahedra as well as a higher ratio of corner-sharing to edge-sharing polyhedra and that exhibit highly localized electronic behavior, while alkyl bipyridinium molecules yield more regular layers with polyhedral edge-sharing that show substantially delocalized electronic behavior. This work allows for the development of design principles based on structure-property relationships and brings the charge transport capabilities of hybrid vanadium bronzes to more technologically relevant levels.

Structural, Electrical, and Electrochemical Properties of a Na2O-V2O5 Ceramic Nanocomposite as an Active Cathode Material for a Na-Ion Battery

In this paper, a relationship between the structure and the electrical properties of a nanocrystalline composite ceramics xNa2O·(100 − x)V2O5 with ‘x’ of 5, 15, 25, 35, and 45 mol%, abbreviated as xNV, was investigated by X-ray diffractometry (XRD), X-ray absorption spectroscopy (XAS), Cyclic Voltammetry (CV), Electrochemical impedance spectroscopy (EIS), and cathode active performance in Na-ion battery (SIB). For the expected sodium vanadium bronzes (NaxV2O5) precipitation, the preparation of xNV was performed by keeping the system in the molten state at 1200 °C for one hour, followed by a temperature decrease in the electric furnace to room temperature at a cooling rate of 10 °C min−1. XRD patterns of the 15NV ceramic exhibited the formation of Na0.33V2O5 and NaV3O8 crystalline phases. Moreover, the V K-edge XANES showed that the absorption edge energy of ceramics 15NV recorded at 5479 eV is smaller than that of V2O5 at 5481 eV, evidently indicating a partial reduction from V5+ to V4+ due to the precipitation of Na0.33V2O5. In the cyclic voltammetry, reduction peaks of 15NV were observed at 1.12, 1.78 V, and 2.69 V, while the oxidation peak showed up only at 2.36 V. The values of the reduction peaks were related to the NaV3O8 crystalline phase. Moreover, the diffusion coefficient of Na+ (DNa+) gradually decreased from 8.28 × 10−11 cm2 s−1 to 1.23 × 10−12 cm2 s−1 with increasing Na2O content (x) from 5 to 45 mol%. In the evaluation of the active cathode performance of xNV in SIB, ceramics 15NV showed the highest discharge capacity 203 mAh g−1 at a current rate of 50 mA g−1. In the wider voltage range from 0.8 to 3.6 V, the capacity retention was maintained at 50% after 30 cycles, while it was significantly improved to 90% in the narrower voltage range from 1.8 to 4.0 V, although the initial capacity decreased to 56 mAh g−1. It is concluded that the precipitation of the Na0.33V2O5 phase improved the structural and electrical properties of 15NV, which provides a high capacity for the Na-ion battery when incorporated as a cathode active material.

Ammonium Vanadium Bronze As a Cathode Material for Calcium-Ion Batteries

Calcium-ion battery (CIB) is considered one of the attractive candidates for post-Li-ion batteries. However, few cathode materials intercalate Ca ions reversibly in nonaqueous electrolytes. Herein, we report the discovery of novel ammonium vanadium bronze (NVO) as a host material of CIBs. We synthesized NVO via a facile hydrothermal method. We determined its chemical composition and crystal structure (P-1) from single-crystal X-ray diffraction data for the first time, revealing unprecedented stoichiometry and crystal structure. It comprises V7O16 layers stacking along the c-axis and two NH4 + ions occupying the interlayer space per formula unit. The galvanostatic discharge/charge cycling demonstrates reversible electrochemical intercalation of Ca2+ ions into the structure. The discharge capacities are ~98 and 87 mAh g-1 for the first and second cycles, respectively. On charge, NH4 + ions are de-intercalated. Simultaneously, the ion-exchange reaction occurs: a small amount of Ca2+ ions are chemically exchanged for NH4 + ions. On discharge, cation insertion occurs, mainly Ca2+ ions and partially the extracted ammonium ions. Small amounts of reinserted ammonium ions play an important role in structural stability, enabling better cycle performance. Understanding the newly discovered mechanism of this material is expected to provide general insights into ammonium vanadium bronzes as new cathode materials.

Al3+ intercalated NH4V4O10 nanosheet on carbon cloth for high-performance aqueous zinc-ion batteries

Ammonium vanadium bronze (NH4V4O10) with open crystal structures and superior theoretical capacity is promising cathode for aqueous zinc-ion batteries (AZIBs). However, the sluggish intrinsic ion/electron kinetics and unsatisfied structural stability remain bottlenecks that limit their further development. Herein, we report a facile synthesis of Al+-intercalated NH4V4O10 nanosheet grown on carbon cloth (Al-NVO@CC) via a one-step hydrothermal reaction. The expanded lattice spacing of the synthesized Al-NVO@CC not only facilitates the Zn2+ ion intercalation/deintercalation but also improves the electrochemical stability in AZIBs. As a result, the cathode shows high reversible capacity (475.8 mA h g-1 at 0.2 A g-1), superior long-term cyclability (152.8 mA h g-1 over 2500 cycles at 5.0 A g-1), as well as excellent rate performance. Moreover, the zinc storage process of Al-NVO@CC and underlying mechanism of the enhanced performance are revealed by ex-situ X-ray powder diffraction (XRD), X-ray photoelectron spectra (XPS) and Transmission electron microscope (TEM) analyses. This study provides a reasonable strategy to promote V-based nanomaterials on CC for the development of AZIBs.

Sodium ion intercalation in vanadium oxide promotes low-temperature NH3-SCR activity: Sodium vanadium bronzes (Na0.33V2O5) for NOx removal

NH3-SCR (selective catalytic reduction) is a key technique for converting harmful NOx to harmless N2 and H2O in exhaust gases. Herein, V2O5, Na0.33V2O5 and Na1.2V3O8 are synthesized by a simple chemical process (the oxalate method) as examples of Na-intercalated vanadium oxide (sodium vanadium oxide bronze) for low-temperature NH3-SCR less than 150 °C. Among them, Na0.33V2O5 shows 92% (dry) and 86% (in the presence of 10 vol% water) NO conversions at 150 °C. The reaction rate of Na0.33V2O5 is 6.1-times higher than that of V2O5, indicating that Na intercalation accelerates NH3-SCR cycles. Mechanistic analysis suggests that the reaction mechanism of Na0.33V2O5 is different from those of other V-based catalysts. Although it has been believed that alkali ions inhibit catalytic cycles of NH3-SCR, the results of this study suggest that alkali ions affect the structural, redox and adsorption properties of bulk V2O5, leading to an increase in NH3-SCR activity.

Long cycle life and high rate aqueous zinc-ion batteries enabled by polypyrrole bridging ammonium vanadium bronze nanosheet cathodes

Aqueous zinc-ion batteries are considered promising large grid energy storage systems because of their low cost and high safety. However, the limited cycle life associated capacity fading in cathode materials, especially at high charge-discharge rates, hampers the practical applications of aqueous zinc-ion batteries. Here we report that ammonium vanadium bronze nanosheets bridged by polypyrrole (NVO@PPy) as cathodes significantly enhance the cycle life and rate performances of aqueous zinc-ion batteries. At a high charge-discharge rate of 28 C (10 A g−1), the discharge capacity gradually increases with the number of cycles and reaches the maximum value of 195 mAh g−1 over 290 cycles, and the reversible capacity maintains 58% (108.8 mAh g−1) even after 2000 cycles. The fast charging-discharging and stable cycling performances are attributed to the high electronic/ionic conductivity of NVO@PPy and the stabilizing effect of PPy on interlayer ammonium. The zinc ion storage mechanism of the NVO@PPy is jointly contributed by intercalation/deintercalation and pseudocapacitance behaviour, the latter not only provides extra capacity but also facilitates fast charge-discharge capability.

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

Aqueous zinc-ion batteries (AZIBs) are emerging as a promising candidate for large grid energy storage due to their abundant availability and high safety. To meet long cycle life requirements, developing a stable cathode with high rate capability is of great importance. Herein, cesium-doped ammonium vanadium bronze Cs0.07NH4V4O10·0.28H2O (CNVO) is synthesized and proposed as a potential cathode material in AZIBs. The doping of Cs+ ions expands the interlayer spacing of the (001) plane from 9.7 to 10.5 Å, which leads to enhanced kinetics and a low energy barrier for the intercalation of Zn2+ ions. The as-synthesized CNVO boasts a two-dimensional (2D) sheet-like morphology with a lateral dimension of about 500 and a low thickness of 9 nm, which enables robust stability during cycling. Additionally, the synergistic interactions among Cs, NH4 and V enhance the electrochemical stability of CNVO during the Zn2+/H+ intercalation/deintercalation reactions. The three-pronged approaches make CNVO nanosheet cathodes deliver a high specific capacity of 475.6 mA h g-1 at 0.1 A g-1, a high energy density of 347.4 W h kg-1 at 74.4 W kg-1 and superb cycling stability with 90.1% capacity retention after 5000 cycles at 10 A g-1. Electrochemical studies indicate that Zn2+ ion storage in CNVO is a comprehensive process involving intercalation and pseudocapacitance, with the latter not only providing extra capacity but also facilitating fast charge-discharge capability.

HXV2O5 Nanocatalysts Combined with Ultrasound for Triple Amplification of Oxidative Stress to Enhance Cancer Catalytic Therapy

AbstractMultiple amplification of tumor oxidative stress has been demonstrated as efficient strategy to enhance the reactive oxygen species (ROS)‐mediated cancer therapy. Herein, vanadium‐based nanocatalysts, hydrogen vanadium bronzes (HXV2O5, for short HVO), were constructed and employed as novel biocatalysts for amplifying tumor oxidative stress and enhancing cancer catalytic therapy. Such HVO nanocatalysts harboring multivalent V element possessed multi‐functional catalytic activity in decomposing H2O2 into ⋅OH and depleting endogenous glutathione (GSH) to dually amplify tumor oxidative stress. Meanwhile, HVO nanocatalysts could also be activated by ultrasound to further triply amplify oxidative stress. The massive intracellular ROS caused mitochondrial dysfunction, DNA damage, cell cycle arrest, and cell proliferation inhibition, further realizing cancer cell death and tumor growth inhibition. Collectively, HVO nanocatalysts highlight the remarkable value of ROS‐mediated cancer therapies.

HX V2 O5 Nanocatalysts Combined with Ultrasound for Triple Amplification of Oxidative Stress to Enhance Cancer Catalytic Therapy.

Multiple amplification of tumor oxidative stress has been demonstrated as efficient strategy to enhance the reactive oxygen species (ROS)-mediated cancer therapy. Herein, vanadium-based nanocatalysts, hydrogen vanadium bronzes (HX V2 O5 , for short HVO), were constructed and employed as novel biocatalysts for amplifying tumor oxidative stress and enhancing cancer catalytic therapy. Such HVO nanocatalysts harboring multivalent V element possessed multi-functional catalytic activity in decomposing H2 O2 into ⋅OH and depleting endogenous glutathione (GSH) to dually amplify tumor oxidative stress. Meanwhile, HVO nanocatalysts could also be activated by ultrasound to further triply amplify oxidative stress. The massive intracellular ROS caused mitochondrial dysfunction, DNA damage, cell cycle arrest, and cell proliferation inhibition, further realizing cancer cell death and tumor growth inhibition. Collectively, HVO nanocatalysts highlight the remarkable value of ROS-mediated cancer therapies.

Facile fabrication of VO2(M) by thermolysis of ammonium metavanadate (NH4VO3) under sealed condition

NH4VO3 is an important vanadium source for the preparation of VO2. In the previous studies, the extra gas or solid reagents consumption is necessary for the preparation of VO2 by using NH4VO3 as vanadium source. The current work proposed a facile way for the fabrication of VO2 (M) by the thermolysis of NH4VO3 under the sealed atmosphere without extra gas or solid reagents consumption. The VO2(M) could be successfully synthesized by two step—thermolysis of NH4VO3 at 400 ​°C under the sealed condition and heat treatment of VO2(B) at 500 ​°C under the N2 condition. The dosage of NH4VO3 and decomposition temperature had significant influences on the thermolysis process under the sealed condition. The NH3 produced by the thermolysis provided a protective atmosphere that prevented the oxidization of VO2(B) by residual O2 in the sealed reactor. Furthermore, the VO2 (M) could be prepared directly under the sealed atmosphere by increasing reaction temperature to 700 ​°C. In this process, NH4VO3 underwent a phase transition as the follows: NH4VO3→ammonium vanadium bronze→VO2(B)→VO2(M). The directly synthesized VO2(M) at 700 ​°C by the thermolysis of NH4VO3 under the sealed condition showed great environmental stability and phase transition performance.

Optimized cyclic and electrochemical performance by organic ion N(CH3)4+ pre-inserted into N(CH3)4V8O20 cathode and hierarchy distributive Zn anode in aqueous zinc ion batteries

Vanadate based cathode materials have been enormously investigated into aqueous zinc-ion batteries (AZIBs) in current research due to high specific capacity and large layer spacing that can accommodate sufficient ions. However, bulk vanadate based cathode materials suffer from a rapid capacity decaying as a result of low electronic conductivity, inferior ion diffusion kinetics and unstable structure during the zinc ion de/intercalation. Meanwhile, the inescapable zinc dendrite formation and reactive irreversibility during long cyclic testing also lead to growing polarization and poor cyclic performance. Herein, we put forward a strategy of structural design by synergistically introducing quaternary ammonium cation within vanadium bronze structure. The desired N(CH3)4V8O20 material, pure monomorph phase, was firstly synthesized by facile one-step hydrothermal method, which owns lattice spacing of 11.5 Å and stable crystalline structure for faster kinetics, higher capacity and better cyclic stability. Combined with the optimized 3D braid architecture of Zn@carbon paper anode, the as-obtained AZIBs exhibit a high capacity of 360 mAh g−1 at 0.5 A g−1. While the current density raises to 100 folds from 0.5 A g−1 to 50 A g−1, appreciable capacity of 105 mAh g−1 and outstanding stability of ultra-long lifespan with capacity retention 97% after 5000 cycles are achieved. Combining the sound investigations of experimental practices and computational research, mechanism of rapid and stable Zn2+ storage was systemically demonstrated. The optimized electrochemical performance could be attributed to highly reversible ion de/intercalation, superior ion diffusion kinetics and no side reactions. This work leads to a new strategy of the design for cathodes in AZIBs and unfolds a new path for the actualization of high-up vanadate based materials.

Boosting Zn2+ Diffusion via Tunnel-Type Hydrogen Vanadium Bronze for High-Performance Zinc Ion Batteries.

Aqueous zinc ion batteries (ZIBs) are emerging as a promising candidate in the post-lithium ion battery era, while the limited choice of cathode materials plagues their further development, especially the tunnel-type cathode materials with high electrochemical performance. Here, a tunnel-type vanadium-based compound based on hydrogen vanadium bronze (HxV2O5) microspheres has been fabricated and employed as the cathode for fast Zn2+ ions' intercalation/deintercalation, which delivers an excellent capacity (425 mAh g-1 at 0.1 A g-1), a remarkable cyclability (91.3% after 5000 cycles at 20 A g-1), and a sufficient energy density (311.5 Wh kg-1). As revealed by the experimental and theoretical results, such excellent electrochemical performance is confirmed to result from the fast ions/electrons diffusion kinetics promoted by the unique tunnel structure (3.7 × 4.22 Å2, along the c direction), which accomplishes a low Zn2+ ion diffusion barrier and the superior electron-transfer capability of HxV2O5. These results shed light on designing tunnel-type vanadium-based compounds to boost the prosperous development of Zn2+ ion storage cathodes.

In-situ electrochemical modification of pre-intercalated vanadium bronze cathodes for aqueous zinc-ion batteries

Vanadium bronzes have been well-demonstrated as promising cathode materials for aqueous zinc-ion batteries. However, conventional single-ion pre-intercalated V2O5 nearly reached its energy/power ceiling due to the nature of micro/electronic structures and unfavourable phase transition during Zn2+ storage processes. Here, a simple and universal in-situ anodic oxidation method of quasi-layered CaV4O9 in a tailored electrolyte was developed to introduce dual ions (Ca2+ and Zn2+) into bilayer δ-V2O5 frameworks forming crystallographic ultra-thin vanadium bronzes, Ca0.12Zn0.12V2O5·nH2O. The materials deliver transcendental maximum energy and power densities of 366 W h kg−1 (478 mA h g−1 @ 0.2 A g−1) and 6627 W kg−1 (245 mA h g−1 @ 10 A g−1), respectively, and the long cycling stability with a high specific capacity up to 205 mA h g−1 after 3000 cycles at 10 A g−1. The synergistic contributions of dual ions and Ca2+ electrolyte additives on battery performances were systematically investigated by multiple in-/ex-situ characterisations to reveal reversible structural/chemical evolutions and enhanced electrochemical kinetics, highlighting the significance of electrolyte-governed conversion reaction process. Through the computational approach, reinforced “pillar” effects, charge screening effects and regulated electronic structures derived from pre-intercalated dual ions were elucidated for contributing to boosted charge storage properties.

Synthesis of hydrocarbon-vanadium thin films by a low energy plasma focus device

Synthesis of hydrocarbon-vanadium thin films by a low energy plasma focus device is reported. The thin films have organometallic structure and organometallic trovacenyl carboxylic acid anhydride (C26H22O3V2) is formed. The vanadium deposition process was achieved in methane atmosphere using different number (10, 20, and 30) of focused shots. Prior to deposition process, surface of pure vanadium substrate and the anode tip were exposed to atmosphere to allow the formation of vanadium trioxide (V2O3) and hydrogen vanadium bronze (HxV2O5) structures. During deposition process, HxV2O5 reacts with methane molecules and C26H22O3V2 molecular structure in nano-grain scale is created. The findings of present study indicates that C26H22O3V2 can be categorized as a semiconductor with band gap energy in the range of 1.20–1.35 eV. Furthermore, it is demonstrated that C26H22O3V2 molecular structure is not Raman active. Characteristics of the V2O3, HxV2O5 and C26H22O3V2 structures are investigated by crystalline, spectroscopy and microscopy methods. The average crystallite size of C26H22O3V2 was roughly 6 nm with almost 16% carbon deposited in the thin films. The Raman results are independent of the number of focused shots.

Development of electrically conductive ZrO2-CaO-Fe2O3-V2O5 glass and glass-ceramics as a new cathode active material for Na-ion batteries with high performance

Glass-ceramics xZrO2•10Fe2O3•(90-x)V2O5 with ‘x’ between 0 and 30 mol% and yZrO2･(20-y)CaO･10Fe2O3･70 V2O5 glass with ‘y’ between 0 and 20 mol%, respectively abbreviated as xZFV and yZCFV, before and after heat treatment at 500 °C for 100 min, were evaluated as potential cathode-active materials for sodium-ion batteries (SIBs). Relationships between physical properties and local structure of xZFV and yZCFV glass-ceramics were investigated by 57Fe-Mössbauer spectroscopy, V K-edge X-ray absorption near edge structure (XANES), X-ray diffractometry (XRD), DC four-probe method and differential thermal analysis (DTA). SIBs containing heat-treated xZFV glass-ceramics showed the highest discharge capacity of 153 mA h g−1 under a current density of 50 mA•g−1, which exhibited a high electrical conductivity of 1.8 × 10−2 Scm−1. Precipitation of V0.05Zr0.95O2 and Fe2V4O13 nanoparticles were confirmed from the XRD pattern of the heat-treated 20ZFV glass, consistent with the lower energy of the pre-edge peak at 5467 eV in the V K-edge XANES spectrum. This result is associated with the reduction of vanadium ions from VV to VIV. It is concluded that the precipitation of stable vanadium bronze phases with high electrical conductivity and structural stability effectively enable the high SIB capacity of these materials.

(NH4 )2 V7 O16 Microbricks as a Novel Anode for Aqueous Lithium-Ion Battery with Good Cyclability.

Searching for novel anode materials to address the issues of poor cycle stability in the aqueous lithium-ion battery system is highly desirable. In this work, ammonium vanadium bronze (NH4 )2 V7 O16 with brick-like morphology has been investigated as an anode material for aqueous lithium-ion batteries and Li+ /Na+ hybrid ion batteries. The two novel full cell systems (NH4 )2 V7 O16 ||Li2 SO4 ||LiMn2 O4 and (NH4 )2 V7 O16 ||Na2 SO4 ||LiMn2 O4 both demonstrate good rate capability and excellent cycling performance. A capacity retention of 78.61 % after 500 cycles at 300 mA g-1 was demonstrated in the (NH4 )2 V7 O16 ||Li2 SO4 ||LiMn2 O4 system, whereas no capacity attenuation is observed in the (NH4 )2 V7 O16 ||Na2 SO4 ||LiMn2 O4 system. The reaction mechanisms of the (NH4 )2 V7 O16 electrode and impedance variation of the two full cells were also researched. The excellent cycling stability suggests that layered (NH4 )2 V7 O16 can be a promising anode material for aqueous rechargeable lithium-ion batteries.

Crystal-Water-Free Potassium Vanadium Bronze (K0.5V2O5) as a Cathode Material for Ca-Ion Batteries

Crystal-Water-Free Potassium Vanadium Bronze (K_0.5V₂O₅) as a Cathode Material for Ca-Ion Batteries