Vanadium-based compounds and heterostructures as functional sulfur catalysts for lithium-sulfur battery cathodes

Lithium-sulfur(Li-S)batteries have attracted wide attention for their high theoretical energy density,low cost,and environmental friendliness.However,the shuttle effect of polysulfides and the insulation of active materials severely restrict the development of Li-S batteries.Constructing conductive sulfur scaffolds with catalytic conversion capability for cathodes is an efficient approach to solving above issues.Vanadium-based compounds and their heterostructures have recently emerged as functional sulfur catalysts supported on conductive scaffolds.These compounds interact with polysulfides via different mechanisms to alleviate the shuttle effect and accelerate the redox kinetics,leading to higher Coulombic efficiency and enhanced sulfur utilization.Reports on vanadium-based nanomaterials in Li-S batteries have been steadily increasing over the past several years.In this review,first,we provide an overview of the synthesis of vanadium-based compounds and heterostructures.Then,we discuss the interactions and constitutive relationships between vanadium-based catalysts and polysulfides formed at sulfur cathodes.We summarize the mechanisms that contribute to the enhancement of electrochemical performance for various types of vanadium-based catalysts,thus providing insights for the rational design of sulfur catalysts.Finally,we offer a perspective on the future directions for the research and development of vanadium-based sulfur catalysts.

Review of vanadium-based electrode materials for rechargeable aqueous zinc ion batteries

In recent years,rechargeable aqueous zinc ion batteries(ZIBs),as emerging energy storage devices,stand out from numerous metal ion batteries.Due to the advantages of low cost,environmentally friendly characteristic and safety,ZIBs can be considered as alternatives to lithium-ion batteries(LIBs).Vanadiumbased compounds with various structures and large layer spacings are considered as suitable cathode candidates for ZIBs.In this review,the recent research advances of vanadium-based electrode materials are systematically summarized.The electrode design strategy,electrochemical performances and energy storage mechanisms are emphasized.Finally,we point out the limitation of vanadium-based materials at present and the future prospect.

Promise and challenge of vanadium-based cathodes for aqueous zinc-ion batteries

Aqueous zinc-ion batteries(ZIBs)have got wide attention with the increasing demands for energy resource recently.It has a number of merits compared with lithium-ion batteries,such as enhanced safety,low cost and environmental friendliness.Vanadium-based materials have been developed to serve as the cathodes of ZIBs for many years.But there are also some challenges to construct high performance ZIBs in the future.Herein,we reviewed the research progress of vanadium-based cathodes and discussed the energy storage mechanisms in ZIBs.In addition,we summarized the major challenges faced by vanadium-based cathodes and the corresponding ways to improve electrochemical performance of ZIBs.Finally,some excellent vanadium-based cathodes are summarized to pave the way for future research in ZIBs.

Vanadium-based polyanionic compounds as cathode materials for sodium-ion batteries:Toward high-energy and high-power applications

Sodium ion batteries(SIBs)have been regarded as one of the alternatives to lithium ion batteries owing to their wide availability and significantly low cost of sodium sources.However,they face serious challenges of low energy&power density and short cycling lifespan owing to the heavy mass and large radius of Na^(+).Vanadium-based polyanionic compounds have advantageous characteristic of high operating voltage,high ionic conductivity and robust structural framework,which is conducive to their high energy&power density and long lifespan for SIBs.In this review,we will overview the latest V-based polyanionic compounds,along with the respective characteristic from the intrinsic crystal structure to performance presentation and improvement for SIBs.One of the most important aspect is to discover the essential problems existed in the present V-based polyanionic compounds for high-energy&power applications,and point out most suitable solutions from the crystal structure modulation,interface tailoring and electrode configuration design.Moreover,some scientific issues of V-based polyanionic compounds shall be also proposed and related future direction shall be provided.We believe that this review can serve as a motivation for further development of novel V-based polyanionic compounds and drive them toward high energy&power applications in the near future.

Pseudocapacitive Vanadium-based Materials toward High-Rate Sodium-Ion Storage

Sodium-ion battery materials and devices are promising candidates for largescale applications,owing to the abundance and low cost of sodium sources.Emerging sodium-ion pseudocapacitive materials provide one approach for achieving high capacity at high rates,but are currently not well understood.Herein,a comprehensive overview of the fundamentals and electrochemical behaviors of vanadium-based pseudocapacitive materials for sodium-ion storage is presented.The insight of sodium-ion storage mechanisms for various vanadium-based materials,including vanadium oxides,vanadates,vanadium sulfides,nitrides,and carbides are systematically discussed and summarized.In particular,areas for further development to improve fundamental understanding of electrochemical and structural properties of materials are identified.Finally,we provide a perspective on the application of pseudocapacitive materials in high-power and high-energy sodium-ion storage devices(e.g.,sodium-ion capacitors).

Fabrication and Analysis of Vanadium-Based Metal Powders for Selective Laser Melting

Vanadium Alloy is a type of advanced nuclear material with many ideal properties compared as traditional nuclear materials, which has very wide and important application in first-wall and blanket structural material for fusion power plant applications. So it has attracted increasing attentions, especially on new manufacturing methods, such as selective laser melting and so on. In this paper, the comparative study of the powders obtained by mechanical mixing method, dry grinding method and wet grinding method respectively was performed to evaluate the effect of ball milling process on the microstructure and degree of alloying of the vanadium-based powder mixtures with the nominal composition of V5Cr5Ti vanadium alloy. The powders prepared by dry grinding method exhibits better spherical-like morphology and degree of alloying than those prepared by mechanical mixing method and wet grinding method, which indicates that dry grinding method can be used to prepare the superfine vanadium alloy powders for selective laser melting. This work provides a new method as well as important insights into the preparation of superfine vanadium alloy powders for selective laser melting additive manufacturing technology.

Preparation of vanadium-based electrode materials and their research progress in solid-state flexible supercapacitors

Solid-state flexible supercapacitors(SCs)have many advantages of high specific capacitance,excellent flexibility,fast charging and discharging,high power density,environmental friendliness,high safety,light weight,ductility,and long cycle stability.They are the ideal choice for the development of flexible energy storage technology in the future,and provide a good prospect for energy storage applications.At present,solid-state flexible SCs are widely used for portable electronic equipment and wearable energy storage equipment,the research of them has become the focus of a growing number of researchers.Electrode material is the key part of SCs and always determines the electrochemical performance of SCs.It has been a hotspot and focus of research.Vanadium-based compounds are considered to be a promising electrode material for SCs because of variable valence,open structure,high theoretical capacity,and low price.Therefore,this study first gives an overview of solid-state flexible SCs,then reviews the current research status of vanadium-based electrode materials in solid-state flexible SCs,and proposes some strategies to solve some problems of vanadium-based electrode materials.

Review of vanadium-based oxide cathodes as aqueous zinc-ion batteries

Research on energy storage technology is a vital part of realizing the dual-carbon strategy at this stage.Aqueous zinc-ion batteries(AZIBs)are favorable competitors in various energy storage devices due to their high energy density,reassuring intrinsic safety,and unique cost advantages.The design of cathode materials is crucial for the large-scale development and application of AZIBs.Vanadium-based oxides with high theoretical capacity,diverse valence states,as well as high electrochemical activity,have been widely used as cathode materials for AZIBs.Unfortunately,there are some obstacles,including low electronic conductivity and sluggish kinetics,hindering their further application in AZIBs.In view of the above,this review will introduce a series of modification methods including morphology design,defect engineering,ingenious combination with conductive materials,and modification of electrolyte and zinc anode according to the intrinsic disadvantage of vanadium oxides and summarize the research progress of various modification methods including zinc storage performance and mechanism.Finally,several reasonable prospects will be proposed to appease the needs of basic research and practical applications according to the current status.

Defect engineering of vanadium-based electrode materials for zinc ion battery

With the quick development of sustainable energy sources, aqueous zinc-ion batteries(AZIBs) have become a highly potential energy storage technology. It is a crucial step to construct desired electrode materials for improving the total performance of AZIBs. In recent years, considerable efforts have focused on the modification of vanadium-based cathode materials. In this review, we summarized defect engineering strategies of vanadium-based cathodes, including oxygen defects, cation vacancies and heterogeneous doping. Then, we discussed the effect of various defects on the electrochemical performance of electrode materials. Finally, we proposed the future challenges and development directions of V-based cathode materials.

A critical review of vanadium-based electrode materials for rechargeable magnesium batteries

Rechargeable magnesium batteries(RMBs)are one of the most promising next-generation energy storage devices due to their high safety and low cost.With a large family and versatile advantageous structures,vanadium-based compounds are highly competitive as electrode materials of RMBs.This review summa-rizes the structural characteristics,electrochemical performance,and refinement methods of vanadium-based materials,including vanadium oxides,vanadium sulfides,vanadates,vanadium phosphates,and vanadium spinel compounds,as RMB cathodes.Although relatively less,vanadium-based materials as RMB anodes are also introduced.According to the application requirements of RMBs,present common strategies are concluded to improve the electrochemical performance of vanadium-based materials;the probably promising development directions are also proposed,which are not limited only to the elec-trode materials,but also the compatible electrolytes and separator materials.In the near future,RMBs are expected from their large-scale application,standing at the forefront of the energy storage era.

Vanadium-based cathodes for aqueous zinc ion batteries: Structure,mechanism and prospects

As an emerging energy storage device with high-safety aqueous electrolytes, low-cost, environmental benignity and large-reserves, the rechargeable aqueous zinc-ion batteries(AZIBs) have attracted more and more attention. Vanadium-based compounds are also supposed as the potential candidate cathode materials for AZIBs due to their wide variety of phases, variable crystal structures and high theoretical capacity. In this review, the recent progress in the development of vanadium-based materials was summarized,and the relationship between the crystal structure types of active materials and Zn-ion transport mechanism was highlighted. During the charge-discharge process, the different electrostatic repulsion between the cations of vanadium-based compounds with different crystal structures and Zn^(2+)results in a variety of the Zn-ion storage mechanisms, which can be significant guidance for designing the advanced batteryelectrode materials for AZIBs. Furthermore, other factors associated with the storage mechanisms, such as electrolyte components and electrode morphology, are discussed. Finally, the strategies to improve the electrical conductivity, inhibit the dissolution and stabilize the crystal structure of vanadium-based compounds are proposed and the future prospects for developing high-energy-density AZIBs are presented.

Recent advances of vanadium-based cathode materials for zinc-ion batteries

Zn-ion batteries(ZIBs) have gained great attention as promising next-generation power sources, because of their low cost, enviable safety and high theoretical capacity. Recently, massive researches have been devoted to vanadium-based materials as cathodes in ZIBs, owing to their multiple valence states, competitive gravimetric energy density, but the capacity degradation, sluggish kinetics, low operating voltage hinder further optimization of their performance in ZIBs. This review summarizes recent progress to increase the interlayer spacing, structural stability, and the diffusion ability of the guest Zn ions, including the insertion of different ions, introduction of defects, design of diverse morphologies, the combination of other materials. We also focus on approaches to promoting the valuable performance of vanadiumbased cathodes, along with the related ongoing scientific challenges and limitations. Finally, the future perspectives and research directions of vanadium-based aqueous ZIBs are provided.

A review on recent developments of vanadium-based cathode for rechargeable zinc-ion batteries

Benefiting from their high safety,low cost,and excellent performance,aqueous zinc-ion batteries are regarded as a promising candidate for next-generation commercial energy storage devices.High-performance cathodes are urgently needed to accelerate practical application of zinc-ion batteries(ZIBs).Among various cathodes reported previously,vanadium-based materials attract a great deal of attention since they hold high capacity and good cycling stability.Though fruitful achievements have been made,there are amounts of crystal structures and energy storage mechanisms are still unclear,which will significantly affect performance of full batteries.This review presents a comprehensive overview of structure characteristics,relevant electrochemical behavior,and proposed energy storage mechanisms of reported vanadium-based materials which provide effective Zn-storage performance.Meanwhile,recent developments of vanadium-based materials for ZIBs are systematically summarized.Last but not least,the future perspectives are also discussed.We hope that this review can provide suggestions to design high-performance electrode materials and promote the development of ZIBs.

Progress and perspective of vanadium-based cathode materials for lithium ion batteries

With the rapid development of various portable electronic devices,lithium ion battery electrode materials with high energy and power density,long cycle life and low cost were pursued.Vanadium-based oxides/sulfides were considered as the ideal next-generation electrode materials due to their high capacity,abundant reserves and low cost.However,the inherent low conductivity and ion diffusion coefficient limit their practical applications in lithium ion batteries.In recent years,vanadium-based electrode materials have been designed into various nanostructures through a variety of nanofabrication processes to overcome the electrochemical performance bottleneck caused by the above disadvantages due to the new properties of nanomaterials that cannot be achieved at the solid level.However,how to obtain high-performance vanadium-based electrode nanomaterials with controllable morphology and structure through low-cost and environmentally friendly processes is still a huge challenge.In this paper,the basic structure,modified morphologies and synthesis methods of vanadium-based electrode materials for lithium ion batteries were reviewed.In addition,the disadvantages,new challenges and future development direction of vanadium electrode materials were also discussed.

钒基催化剂催化苯羟基化制苯酚反应机理

苯羟基化制苯酚是C—H键向C—O键转化及富有挑战性的课题之一。该文论述了钒基催化剂催化苯羟基化制苯酚反应机理的研究进展。以钒活性中心为主线,着重从自由基、非自由基和双催化活性机理进行了详细介绍,同时分析了双催化活性中心催化剂高效催化的本质和重要性。提出此类催化体系及催化机理能够解决苯环上C—H键难活化和苯酚的深度氧化等问题,是经济与安全并存的苯酚合成方法,依托已有的催化反应机理,开发更稳定且高性能的催化剂,以促进烃类有机化合物资源利用的原始创新。

氢化改性钒基催化剂降解氯苯的机理研究

为了在低温下高效、稳定地降解挥发性氯代有机污染物(CVOCs),以偏钒酸铵为VO_(x)前驱体制备2D纳米片与3D纳米结构的互穿多孔网络结构的L-V_(2)O_(5)催化剂,并通过氢化技术对催化剂中部分V^(5+)进行还原(H-V_(2)O_(5))。结果表明,该氢化技术降低了催化剂中部分V^(5+)的化学价态,增加了V—O(Ⅱ)和V—O(Ⅳ)上的氧空位数量和催化剂表面活性氧数量。在275℃时,相较于L-V_(2)O_(5),H-V_(2)O_(5)对氯苯催化降解的效率提高了约40%。

Dual-Defect Engineering Strategy Enables High-Durability Rechargeable Magnesium-Metal Batteries

Rechargeable magnesium-metal batteries(RMMBs)are promising next-generation secondary batteries;however,their development is inhibited by the low capacity and short cycle lifespan of cathodes.Although various strategies have been devised to enhance the Mg^(2+)migration kinetics and structural stability of cathodes,they fail to improve electronic conductivity,rendering the cathodes incompatible with magnesium-metal anodes.Herein,we propose a dual-defect engineering strategy,namely,the incorporation of Mg^(2+)pre-intercalation defect(P-Mgd)and oxygen defect(Od),to simultaneously improve the Mg^(2+)migration kinetics,structural stability,and electronic conductivity of the cathodes of RMMBs.Using lamellar V_(2)O_(5)·nH_(2)O as a demo cathode material,we prepare a cathode comprising Mg_(0.07)V_(2)O_(5)·1.4H_(2)O nanobelts composited with reduced graphene oxide(MVOH/rGO)with P-Mgd and Od.The Od enlarges interlayer spacing,accelerates Mg^(2+)migration kinetics,and prevents structural collapse,while the P-Mgd stabilizes the lamellar structure and increases electronic conductivity.Consequently,the MVOH/rGO cathode exhibits a high capacity of 197 mAh g^(−1),and the developed Mg foil//MVOH/rGO full cell demonstrates an incredible lifespan of 850 cycles at 0.1 A g^(−1),capable of powering a light-emitting diode.The proposed dual-defect engineering strategy provides new insights into developing high-durability,high-capacity cathodes,advancing the practical application of RMMBs,and other new secondary batteries.

低SO_(2)氧化率钒钛基选择性催化还原脱硝催化剂研究进展

选择性催化还原(SCR)脱硝技术是目前烟气氮氧化物控制最主流的技术。商用SCR催化剂主要由V 2O 5-WO_(3)(MoO_(3))/TiO_(2)组成,其中V 2 O 5不仅对烟气中的氮氧化物有催化还原作用,同时也能促进SO_(2)的氧化,导致硫酸铵盐的生成,进而造成催化剂孔道堵塞,活性位点减少,使催化剂活性降低,脱硝效率下降。基于此,主要探讨了钒钛基SCR催化剂对SO_(2)的氧化机理及其研究进展,总结了国内外降低钒钛基SCR催化剂SO_(2)氧化率的一些主要措施,并对此进行了分析和讨论。

苯酐合成的反应网络及催化反应机制研究现状与展望

邻苯二甲酸酐(简称苯酐)是合成增塑剂、涂料等高价值精细化学品的重要原料,在工业生产中以邻法苯酐合成工艺为主,萘法合成工艺为辅,其中钒系催化剂因具有高苯酐选择性而备受关注。为了提高苯酐收率、降低床层温度,催化剂在工业应用中已逐步进入多床层、高进料负荷的发展阶段。本文以邻法苯酐为主要研究对象,简要讨论了催化剂的发展历程,重点关注合成工艺路线及催化机制研究进展。工业催化剂易因生成积炭、活性组分流失、TiO_(2)晶相转变等导致其失活,因此也重点探讨了催化剂的失活机制。最后对苯酐工艺的发展提出了展望,为解决当前生产工艺存在的高耗能、高碳排放、催化剂寿命短等挑战,未来苯酐合成应致力于开发新型高效催化剂和绿色反应新工艺,以推动该技术的可持续发展。

乙丙共聚Ziegler-Natta钒系催化体系活化剂研究进展

乙丙橡胶钒系催化体系因其所制备产品序列分布均匀、结晶度低、组成分布较窄等优势,广泛应用于国内外乙丙橡胶生产企业。然而,钒系催化剂存在热稳定性差、活性中心寿命短、催化剂失活较快等问题,极大地降低了催化效率,提高了生产成本。为了实现降本增效,利用活化剂使得已经失活的钒系催化剂再活化,是工业上提高乙丙橡胶钒系催化剂活性的主要手段。本文综述了活化剂在国内外乙丙橡胶钒系催化体系应用方面的研究进展以及活化剂的加入对乙丙共聚反应活性以及所制备乙丙橡胶性能的影响,总结了活化剂在钒系催化体系中的活化机理。