The emergency of high-power electrical appliances has put forward higher requirements for the power density of lithium-ion batteries.Vanadium oxides with large theoretical capacities and high operating voltages are co...The emergency of high-power electrical appliances has put forward higher requirements for the power density of lithium-ion batteries.Vanadium oxides with large theoretical capacities and high operating voltages are considered as prospective alternatives for the cathode of a new generation of lithium-ion batteries.However,the poor rate and cycling performance caused by the sluggish electrons/lithium transportation,irreversible phase changes,vanadium dissolution and large volume changes during the repeated lithium intercalation/deintercalation hinder their commercial development.Several optimizing routes have been carried out and extensively explored to address these problems.Taking V_(2)O_(5),VO_(2)(B),V_(6)O_(13),and V_(2)O_(3)as examples,this article reviewed their crystal structures and lithium storage reactions.Besides,recent progress in modification methods for the electrochemical insufficiencies of vanadium oxides,including nanostructure,heterogeneous atom doping,composite and self-supported electrodes has been systematically summarized and finally,the challenges for the industrialization of vanadium oxide cathodes and their development opportunities are proposed.展开更多
Potassium-ion batteries(PIBs)have been considered as promising candidates in the post-lithium-ion battery era.Till now,a large number of materials have been used as electrode materials for PIBs,among which vanadium ox...Potassium-ion batteries(PIBs)have been considered as promising candidates in the post-lithium-ion battery era.Till now,a large number of materials have been used as electrode materials for PIBs,among which vanadium oxides exhibit great potentiality.Vanadium oxides can provide multiple electron transfers during electrochemical reactions because vanadium possesses a variety of oxidation states.Meanwhile,their relatively low cost and superior material,structural,and physicochemical properties endow them with strong competitiveness.Although some inspiring research results have been achieved,many issues and challenges remain to be further addressed.Herein,we systematically summarize the research progress of vanadium oxides for PIBs.Then,feasible improvement strategies for the material properties and electrochemical performance are introduced.Finally,the existing challenges and perspectives are discussed with a view to promoting the development of vanadium oxides and accelerating their practical applications.展开更多
Exploring suitable high-capacity V_(2)O_(5)-based cathode materials is essential for the rapid advancement of aqueous zinc ion batteries(ZIBs).However,the typical problem of slow Zn^(2+)diffusion kinetics has severely...Exploring suitable high-capacity V_(2)O_(5)-based cathode materials is essential for the rapid advancement of aqueous zinc ion batteries(ZIBs).However,the typical problem of slow Zn^(2+)diffusion kinetics has severely limited the feasibility of such materials.In this work,unique hydrated vanadates(CaVO,BaVO)were obtained by intercalation of Ca^(2+)or Ba^(2+)into hydrated vanadium pentoxide.In the CaVO//Zn and BaVO//Zn batteries systems,the former delivered up to a 489.8 mAh g^(-1)discharge specific capacity at 0.1 A g^(-1).Moreover,the remarkable energy density of 370.07 Wh kg^(-1)and favorable cycling stability yard outperform BaVO,pure V_(2)O_(5),and many reported cathodes of similar ionic intercalation compounds.In addition,pseudocapacitance analysis,galvanostatic intermittent titration(GITT)tests,and Trasatti analysis revealed the high capacitance contribution and Zn^(2+)diffusion coefficient of CaVO,while an in-depth investigation based on EIS elucidated the reasons for the better electrochemical performance of CaVO.Notably,ex-situ XRD,XPS,and TEM tests further demonstrated the Zn^(2+)insertion/extraction and Zn-storage mechanism that occurred during the cycle in the CaVO//Zn battery system.This work provides new insights into the intercalation of similar divalent cations in vanadium oxides and offers new solutions for designing cathodes for high-capacity aqueous ZIBs.展开更多
Vanadium oxides,par-ticularly hydrated forms like V_(2)O_(5)·nH_(2)O(VOH),stand out as promising cathode candidates for aqueous zinc ion batteries due to their adjustable layered structure,unique electronic chara...Vanadium oxides,par-ticularly hydrated forms like V_(2)O_(5)·nH_(2)O(VOH),stand out as promising cathode candidates for aqueous zinc ion batteries due to their adjustable layered structure,unique electronic characteristics,and high theoretical capacities.However,challenges such as vanadium dissolution,sluggish Zn^(2+)diffusion kinetics,and low operating voltage still hinder their direct application.In this study,we present a novel vanadium oxide([C_(6)H_(6)N(CH_(3))_(3)]_(1.08)V_(8)O_(20)·0.06H_(2)O,TMPA-VOH),developed by pre-inserting trimethylphenylammonium(TMPA+)cations into VOH.The incorporation of weakly polarized organic cations capitalizes on both ionic pre-intercalation and molecular pre-intercalation effects,resulting in a phase and morphology transition,an expansion of the interlayer distance,extrusion of weakly bonded interlayer water,and a substantial increase in V^(4+)content.These modifications synergistically reduce the electrostatic interactions between Zn^(2+)and the V-O lattice,enhancing structural stability and reaction kinetics during cycling.As a result,TMPA-VOH achieves an elevated open circuit voltage and operation voltage,exhibits a large specific capacity(451 mAh g^(-1)at 0.1 A g^(-1))coupled with high energy efficiency(89%),the significantly-reduced battery polarization,and outstanding rate capability and cycling stability.The concept introduced in this study holds great promise for the development of high-performance oxide-based energy storage materials.展开更多
A new layered vanadium oxide [ NH3 （ CH2 ）2NH（ CH2 ）2NH3 ] [ V6O14 ] （ compound 1 ） was synthesized and characterized by elemental analysis, IR spectrometry and single crystal X ray diffraction. The compound cry...A new layered vanadium oxide [ NH3 （ CH2 ）2NH（ CH2 ）2NH3 ] [ V6O14 ] （ compound 1 ） was synthesized and characterized by elemental analysis, IR spectrometry and single crystal X ray diffraction. The compound crystallizes ina monoclinic space group P2（1）/n with a = 1.0254（2） nm, b =0.6739（2） nm, c = 1.2400（2） nm, ,8 = 93.88 （ 3 ） °, V = 0. 8549 （ 3 ）nm^3, Z = 2, R1 = 0. 0366, wR2 = 0. 1038. Compound 1 consists of two-dimensional mixed-valence vanadium oxide layers parallelling to the bc plane. The anti-tumor activity of the compound was estimated in three human tumor cell lines in vitro.展开更多
Vanadium oxides are considered as one of the most promising cathode materials for aqueous zinc-ion batteries(ZIBs).However,the bulk morphology and strong electrostatic interaction between divalent Zn^(2+) and host mat...Vanadium oxides are considered as one of the most promising cathode materials for aqueous zinc-ion batteries(ZIBs).However,the bulk morphology and strong electrostatic interaction between divalent Zn^(2+) and host materials inevitably cause an ultra-long activation process and poor performance.To address these issues,multiscale modification of commercial bulk V_(2)O_(5) was developed herein,which simultaneously optimized the valence states,interlayer spacing,and macrostructure in a facile one-step reduction process,resulting in a novel accordion-like V_(10)O_(24)·12H_(2)O.The synergistic effect of polyvalent vanadium,large interlayer spacing of 14.2Å,and unique open structure endowed V_(10)O_(24)·12H_(2)O with high electronic conductivity,rapid ion diffusion channels,and stable structure.A high specific capacity of 306.9 mA h g^(−1) and long durability for 1000 cycles with a capacity retention up to 81% was achieved when V_(10)O_(24)·12H_(2)O served as the cathode material for ZIBs.This multiscale modulation strategy demonstrates an effective and economical method for converting traditional vanadium oxides for use as highperformance cathodes for ZIBs.展开更多
Molecular vanadium oxides are promising active materials for cathodes in lithium and post-lithium batteries due to their high redox activity,low molecular weight and facile tuneability.However,a major challenge for th...Molecular vanadium oxides are promising active materials for cathodes in lithium and post-lithium batteries due to their high redox activity,low molecular weight and facile tuneability.However,a major challenge for this application is the transformation of the molecular clusters into solid-state oxides under typical electrode fabrication conditions.Here,we report a molecular crystal engineering approach for the stabilization of molecular vanadium oxides in the crystal lattice,enabling initial studies on reversible electron storage in a lithium ion battery test cell.展开更多
Vanadium oxides with a layered structure are promising candidates for both lithium-ion batteries and sodium-ion batteries （SIBs）. The self-template approach, which involves a transformation from metal-organic framew...Vanadium oxides with a layered structure are promising candidates for both lithium-ion batteries and sodium-ion batteries （SIBs）. The self-template approach, which involves a transformation from metal-organic frameworks （MOFs） into porous metal oxides, is a novel and effective way to achieve desirable electrochemical performance. In this stud~ porous shuttle-like vanadium oxides （i.e., V205, V203/C） were successfully prepared by using MIL-88B （V） as precursors with a specific calcination process. As a proof-of-concept application, the as- prepared porous shuttle-like VaOdC was used as an anode material for SIBs. The porous shuttle-like V203/C, which had an inherent layered structure with metallic behavior, exhibited excellent electrochemical properties. Remarkable rate capacities of 417, 247, 202, 176, 164, and 149 mAh.g-1 were achieved at current densities of 50, 100, 200, 500, 1,000, and 2,000 mA.g-1, respectively. Under cycling at 2 A.g-1, the specific discharge capacity reached 181 mAh.g-1, with a low capacity fading rate of 0.032% per cycle after 1,000 cycles. Density functional theory calculation results indicated that Na ions preferred to occupy the interlamination rather than the inside of each layer in the V203. Interestingly, the special layered structure with a skeleton of dumbbell-like V-V bonds and metallic behavior was maintained after the insertion of Na ions, which was beneficial for the cycle performance. We consider that the MOF precursor of MIL-88B （V） can be used to synthesize other porous V-based materials for various applications.展开更多
Current research on vanadium oxides in lithium ion batteries （LIBs） considers them as cathode materials, whereas they are rarely studied for use as anodes in LIBs because of their low electrical conductivity and rap...Current research on vanadium oxides in lithium ion batteries （LIBs） considers them as cathode materials, whereas they are rarely studied for use as anodes in LIBs because of their low electrical conductivity and rapid capacity fading. In this work, hydrogenated vanadium oxide nanoneedles were prepared and incorporated into freeze-dried graphene foam. The hydrogenated vanadium oxides show greatly improved charge-transfer kinetics, which lead to excellent electrochemical properties. When tested as anode materials （0.005-3.0 V vs. Li/Li＋） in LIBs, the sample activated at 600℃ exhibits high specific capacity （-941 mA-h-g-1 at 100 mA.g-1） and high-rate capability （-504 mA·h·g-1 at 5 A·g-1）, as well as excellent cycling performance （-285 mA.h.g-1 in the 1,000th cycle at 5A-g-1）. These results demonstrate the promising application of vanadium oxides as anodes in LIBs.展开更多
Aqueous zinc‐ion batteries(ZIBs)are regarded as among the most promising candidates for large‐scale grid energy storage,owing to their high safety,low costs,and environmental friendliness.Over the past decade,vanadi...Aqueous zinc‐ion batteries(ZIBs)are regarded as among the most promising candidates for large‐scale grid energy storage,owing to their high safety,low costs,and environmental friendliness.Over the past decade,vanadium oxides,which are exemplified by V2O5,have been widely developed as a class of cathode materials for ZIBs,where the relatively high theoretical capacity and structural stability are among the main considerations.However,there are considerable challenges in the construction of vanadium‐based ZIBs with high capacity,long lifespan,and excellent rate performance.Simple widenings of the interlayer spacing in the layered vanadium oxides by pre‐intercalations appear to have reached their limitations in improving the energy density and other key performance parameters of ZIBs,although various metal ions(Na+,Ca2+,and Al3+)and even organic cations/groups have been explored.Herein,we discuss the advances made more recently,and also the challenges faced by the high‐performance vanadium oxides(V2O5‐based)cathodes,where there are several strategies to improve their electrochemical performance ranging from the new structural designs down to sub‐nano‐scopic/molecular/atomic levels,including cation pre‐intercalation,structural water optimization,and defect engineering,to macroscopic structural modifications.The key principles for an optimal structural design of the V2O5‐based cathode materials for high energy density and fast‐charging aqueous ZIBs are examined,aiming at paving the way for developing energy storage designed for those large scales,high safety,and low‐cost systems.展开更多
Vanadium oxides have attracted extensive interest as electrode materials for many electrochemical energy storage devices owing to the features of abundant reserves,low cost,and variable valence.Based on the in-depth u...Vanadium oxides have attracted extensive interest as electrode materials for many electrochemical energy storage devices owing to the features of abundant reserves,low cost,and variable valence.Based on the in-depth understanding of the energy storage mechanisms and reasonable design strategies,the performances of vanadium oxides as electrodes for batteries have been significantly optimized.Compared to crystalline vanadium oxides,amorphous vanadium oxides(AVOs)show many unique properties,including large specific surface area,excellent electrochemical stability,lots of defects and active sites,fast ion kinetics,and high elasticity.This review gives a comprehensive overview of the recent progress on AVOs for different energy storage systems,such as alkali metal ion batteries,multivalent ion batteries,and supercapacitors with a special focus on the preparation strategies.The basic mechanisms for energy storage performance improvements of AVOs as compared to their crystalline counterparts are also introduced.Finally,challenges faced by AVOs are discussed and future development prospects are also proposed.This review aims to provide a comprehensive knowledge of AVOs and is expected to promote the development of high-performance electrodes for batteries.展开更多
The diverse valence and spatial structure endow vanadium oxides with significant potential in the field of aqueous zinc ion batteries(AZIBs).Although the conventional ion doping method mitigates the intrinsically slug...The diverse valence and spatial structure endow vanadium oxides with significant potential in the field of aqueous zinc ion batteries(AZIBs).Although the conventional ion doping method mitigates the intrinsically sluggish kinetics,it exacerbates the erosion of Zn^(2+)/H^(+)and free water within the lattice structure,leading to inferior structural stability and capacity fading.Herein,a synchronous dual-modification strategy is introduced to improve the electrochemical performance of the V_(6)O_(13)cathode through an ingenious hydrolysis process involving K_(2)Cr_(2)O_(7).Experimental and calculated results demonstrate that the coating layer formed by chromium oxide supports the structural firmness and strengthens the interfacial chemistry,based on increased electrochemical activity by K^(+)intercalation.Consequently,the optimized sample delivers a capacity of 418 mAh g^(-1)at 0.1 A g^(-1),and excellent cyclic stability of 205 mAh g^(-1)after 6000 cycles at 10 A g^(-1).It is fully charged at a small current of 0.5 A g^(-1)to maintain a reversible capacity of 346 mAh g^(-1)after 72 h in an open circuit state,and there is no obvious capacity decay,highlighting the crucial protective effect of the inactive coating layer.This work presents a straightforward and reliable approach to effectively harmonize the relationship between activity and structural stability for advanced AZIBs cathode.展开更多
The issue of water molecule activity in aqueous zinc-ion batteries presents a significant challenge.During the charging and discharging process,the strong polarity of water molecules tends to cause the dissolution of ...The issue of water molecule activity in aqueous zinc-ion batteries presents a significant challenge.During the charging and discharging process,the strong polarity of water molecules tends to cause the dissolution of cathode materials,which reduces the cycle stability and specific capacity,consequently limiting the practical application of zinc-ion batteries.In this work,hydroxypropylβ-cyclodextrin(HP-β-CD),a special stereo cyclic organic molecule with hydrophobic inner cavity and hydrophilic outer cavity,is used as the intercalator for hydrated vanadium oxide(VOH)to enlarge the layer spacing and enhance the hydrophobicity of the cathode material.The larger interlayer spacing(13.9Å)of HP-β-CD-VOH is beneficial for improving ion mobility and the intrinsic electrochemical reaction kinetics.HP-β-CD-VOH delivers a discharge capacity of 336.7 mAh g^(-1)at 0.2 A g^(-1)and high-rate capability(242 mAh g^(-1)at 5 A g^(-1)).Due to the hydrophobic property of HP-β-CD in the interlayer pillar,the vanadium dissolution effect of polar water molecules can be reduced during charge and discharge;HP-β-CDVOH demonstrates sustained high efficiency and extended cycle longevity,maintaining a remarkable durability of 6000 cycles at a current density of 10 A g^(-1).This study presents an effective strategy for developing high-performance aqueous zinc-ion battery cathode materials.展开更多
Ni-ion aqueous batteries(NIBs)were considered an important development direction for aqueous batteries due to the high theoretical capacity(913 mA h g^(-1))and volume capacity(8136 mA h cm^(-3))of nickel metal.Herein,...Ni-ion aqueous batteries(NIBs)were considered an important development direction for aqueous batteries due to the high theoretical capacity(913 mA h g^(-1))and volume capacity(8136 mA h cm^(-3))of nickel metal.Herein,an electrolyte additive(dodecyl trimethyl ammonium chloride,DTAC)was used to improve the electrolyte environment,achieve efficient transport of Ni-ion,and combine the intercalated vanadium oxide cathodes to realize novel strategy NIBs.Firstly,the introduction of trace amounts of DTAC improved the high-concentration NiCl_(2)(4.2 M)electrolyte environment and reconstructed the hydrogen bond network.Molecular dynamics(MD)calculations and electrochemical results indicated that DTAC contributed to the desolvation process of Ni^(2+)and the realization of fast dynamics.The results of Ni symmetric cells demonstrated that DTAC enhanced the rapid migration of Ni-ion and achieved longer cycling stability(1750/1500 h at 0.2/0.5 mA cm^(-2)without obvious short circuits).Secondly,the insertion of organic small molecules(pyrrolidine)into vanadium oxide(V_(2)O_(5))to expand the interlayer spacing promoted the Ni-ion storage capacity of the cathodes.The capacity retention rate of Ni full battery after 6000 cycles at 5 A g^(-1)reached 82.17%.This work provided a novel strategy for the development of Ni-ion aqueous batteries.展开更多
Pre-intercalation is the mainstream approach to inhibit the unpredicted structural degradation and the sluggish kinetics of Zn-ions migrating in vanadium oxide cathode of aqueous zinc-ion batteries(AZIBs),which has be...Pre-intercalation is the mainstream approach to inhibit the unpredicted structural degradation and the sluggish kinetics of Zn-ions migrating in vanadium oxide cathode of aqueous zinc-ion batteries(AZIBs),which has been extensively explored over the past 5 years.The functional principles behind the improvement are widely discussed but have been limited to the enlargement of interspace between VO layers.As the different types of ions could change the properties of vanadium oxides in various ways,the review starts with a comprehensive overview of pre-intercalated vanadium oxide cathode with different types of molecules and ions,such as metal ions,water molecules,and non-metallic cations,along with their functional principles and resulting performance.Furthermore,the pre-intercalated vanadium cathodes reported so far are summarized,comparing their interlayer space,capacity,cycling rate,and capacity retention after long cycling.A discussion of the relationship between the interspace and the performance is provided.The widest interspaces could result in the decay of the cycling stability.Based on the data,the optimal interspace is likely to be around 12?indicating that precise control of the interspace is a useful method.However,more consideration is required regarding the other impacts of pre-intercalated ions on vanadium oxide.It is hoped that this review can inspire further understanding of pre-intercalated vanadium oxide cathodes,paving a new pathway to the development of advanced vanadium oxide cathodes with better cycling stability and larger energy density.展开更多
Vanadium oxide(VO_(x))has garnered significant attention in the realm of resistive random-access memory(RRAM)owing to its outstanding resistive switching characteristics.However,the ambiguous mechanisms of resistive s...Vanadium oxide(VO_(x))has garnered significant attention in the realm of resistive random-access memory(RRAM)owing to its outstanding resistive switching characteristics.However,the ambiguous mechanisms of resistive switching and inferior stability hinder its practical applications.Herein,an RRAM named VO_(x)/TiO_(2)/n^(++)Si device is prepared.It displays bipolar resistive switching behavior and shows superior cycle endurance(>200),a significantly high on/off ratio(>10^(2))and long-term stability.The tremendous improvement in the stability of the VO_(x)/TiO_(2)/n^(++)Si device compared with the Cu/VOx/n^(++)Si device is due to the p-i-n structure of VO_(x)/TiO_(2)/n^(++)Si.The switching mechanism of the VO_(x)/TiO_(2)/n^(++)Si device is attributed to the growth and annihilation of Cu conductive filaments.展开更多
Although the enhancement of the zinc storage performance of layered vanadium oxides can be realized by the ionic pre-intercalation strategy,it also occupies a large number of active sites and thus fails to release the...Although the enhancement of the zinc storage performance of layered vanadium oxides can be realized by the ionic pre-intercalation strategy,it also occupies a large number of active sites and thus fails to release the full potential of vanadium oxides.Here,vanadium oxide nanobelts with sodium-poor and oxygen defect-rich were constructed by regulating the content of pre-embedded sodium ions to strike a balance between pre-embedded ions and structural stability.The introduction of trace sodium ions not only increases the spacing of vanadium oxide layers but also occupies as few active sites as possible,which provides the possibility of massive storage,rapid diffusion and stabilization of the host structure for zinc ions.Moreover,the abundant oxygen defects transform the ion transport pathway from two-dimensional to three-dimensional,which greatly improves the ion transport rate in the host phase.Due to these advantages,the synthesized vanadium oxide nanobelts exhibit remarkable electrochemical properties,and this work provides a new idea for the design of structurally stable layered vanadium oxides with excellent properties.展开更多
Vanadium-based materials are recognized as promising cathodes for high-energy-density aqueous zincion batteries(AZIBs).However,their inherent low intrinsic conductivities and sluggish reaction kinetics curtail their c...Vanadium-based materials are recognized as promising cathodes for high-energy-density aqueous zincion batteries(AZIBs).However,their inherent low intrinsic conductivities and sluggish reaction kinetics curtail their capacity release.Here,we enhanced the electron and ion transport properties of vanadium-based cathodes through heterojunction engineering,coupled with in situ electrochemical activation,significantly enhancing an unprecedented zinc-ion storage capacity and rapid kinetic performance.A heterostructured V_(2)O_(3)/g-C_(3)N_(4)(V_(2)O_(3)/CN)precursor was synthesized via a calcination process firstly.When employed as a cathode in AZIBs,this precursor undergoes an in situ phase transformation into Zn_(3)(OH)_(2-)V_(2)O_(7)-2H_(2)O/C_(3)N_(4)(ZVOH/CN)during the inaugural charging process,while retaining its heterojunction structure.Both electrochemical assessments and theoretical calculations revealed that ZVOH/CN exhibits superior zinc-ion adsorption and migration capabilities compared to conventional vanadium-based cathodes.The formation of the heterojunction amplifies the material's electronic conductivity and ion diffusion kinetics.As a result,the optimal ZVOH/CN composite electrode showcases a remarkable capacity of 518.5 mAh g^(-1)at 0.5 A g^(-1),superior rate performance of 177.8 mAh g^(-1)at 20 A g^(-1),and impressive cycling stability.This work offers a novel design strategy for vanadium-based composite materials as highperformance AZIB cathodes.展开更多
Experiments comparing microwave blank roasting and conventional blank roasting for typical vanadium-bearing stone coal from Hubei Province in central China, in which vanadium is present in muscovite, were conducted to...Experiments comparing microwave blank roasting and conventional blank roasting for typical vanadium-bearing stone coal from Hubei Province in central China, in which vanadium is present in muscovite, were conducted to investigate the effects of roasting tempera- ture, roasting time, H2SO4 concentration, and leaching time on vanadium extraction. The results show that the vanadium leaching efficiency is 84% when the sample is roasted at 800℃ for 30 min by microwave irradiation and the H2SO4 concentration, liquid/solid ratio, leaching temperature, and leaching time are set as 20vo1%, 1.5：1 mL.g-1, 95℃, and 8 h, respectively. However, the vanadium leaching efficiency achieved for the sample subjected to conventional roasting at 900℃ for 60 min is just 71% under the same leaching conditions. Scanning electron microscopy （SEM） analysis shows that the microwave roasted samples contain more cracks and that the particles are more porous compared to the conventionally roasted samples. According to the results of X-ray diffraction （XRD） and Fourier-transform infrared （FTIR） analyses, neither of these roasting methods could completely destroy the mica lattice structure under the experimental conditions; however, both methods deformed the muscovite structure and facilitated the leaching process. Comparing with conventional roasting, microwave roasting causes a greater deformation of the mineral structure at a lower temperature for a shorter roasting time.展开更多
Graphene is a type of promising electrode material for high-energy and high-power density supercapacitors,but its electrochemical performance is greatly limited by the restacking problem.In this work,we reported a fac...Graphene is a type of promising electrode material for high-energy and high-power density supercapacitors,but its electrochemical performance is greatly limited by the restacking problem.In this work,we reported a facile approach to synthesis graphene with chemically bonded vanadium oxide(VOx)nanoparticles and demonstrated that chemically-bonded VOxnanoparticles can effectively prevent the graphene sheets from restacking and hence improve the electrochemical performance.The capacitance of VOxbonded graphene increases to 272 F/g compared to 183 F/g of pristine graphene in 1 M H3PO4 aqueous electrolyte at 2 A/g.The VOx-bonded graphene also showed improved rate capability in both H3PO4 and ionic liquid electrolytes.The capacitance retention increases to 54.5%from 28.5%at 100 A/g(compare to2 A/g)in H3PO4 and increases to 65.1%from 46.3%at 2 A/g(compare to 0.2 A/g)in neat ionic liquid.A high energy density of 84.4 Wh/kg is obtained within the voltage window of 4 V in ionic liquid.Even at a high-power density of 1000 W/kg,the VOx-bonded graphene shows a high energy density of 47.3 Wh/kg.展开更多
基金supported by the National Natural Science Foundation of China,NSFC(51772205,51772208)the General Program of Municipal Natural Science Foundation of Tianjin(17JCYBJC17000,17JCYBJC22700)。
文摘The emergency of high-power electrical appliances has put forward higher requirements for the power density of lithium-ion batteries.Vanadium oxides with large theoretical capacities and high operating voltages are considered as prospective alternatives for the cathode of a new generation of lithium-ion batteries.However,the poor rate and cycling performance caused by the sluggish electrons/lithium transportation,irreversible phase changes,vanadium dissolution and large volume changes during the repeated lithium intercalation/deintercalation hinder their commercial development.Several optimizing routes have been carried out and extensively explored to address these problems.Taking V_(2)O_(5),VO_(2)(B),V_(6)O_(13),and V_(2)O_(3)as examples,this article reviewed their crystal structures and lithium storage reactions.Besides,recent progress in modification methods for the electrochemical insufficiencies of vanadium oxides,including nanostructure,heterogeneous atom doping,composite and self-supported electrodes has been systematically summarized and finally,the challenges for the industrialization of vanadium oxide cathodes and their development opportunities are proposed.
基金the Shenyang University of Technology(QNPY202209-4)the Key R&D project of Liaoning Province of China(2020JH2/10300079)+2 种基金the“Liaoning BaiQianWan Talents Program”(2018921006)the Liaoning Revitalization Talents Program(XLYC1908034)the National Natural Science Foundation of China(21571132).
文摘Potassium-ion batteries(PIBs)have been considered as promising candidates in the post-lithium-ion battery era.Till now,a large number of materials have been used as electrode materials for PIBs,among which vanadium oxides exhibit great potentiality.Vanadium oxides can provide multiple electron transfers during electrochemical reactions because vanadium possesses a variety of oxidation states.Meanwhile,their relatively low cost and superior material,structural,and physicochemical properties endow them with strong competitiveness.Although some inspiring research results have been achieved,many issues and challenges remain to be further addressed.Herein,we systematically summarize the research progress of vanadium oxides for PIBs.Then,feasible improvement strategies for the material properties and electrochemical performance are introduced.Finally,the existing challenges and perspectives are discussed with a view to promoting the development of vanadium oxides and accelerating their practical applications.
基金the financial support from the National Key Research and Development Program of China(2022YFA1207503)the Giga Force Electronics Interdisciplinary Funding(JJHXM002208-2023)。
文摘Exploring suitable high-capacity V_(2)O_(5)-based cathode materials is essential for the rapid advancement of aqueous zinc ion batteries(ZIBs).However,the typical problem of slow Zn^(2+)diffusion kinetics has severely limited the feasibility of such materials.In this work,unique hydrated vanadates(CaVO,BaVO)were obtained by intercalation of Ca^(2+)or Ba^(2+)into hydrated vanadium pentoxide.In the CaVO//Zn and BaVO//Zn batteries systems,the former delivered up to a 489.8 mAh g^(-1)discharge specific capacity at 0.1 A g^(-1).Moreover,the remarkable energy density of 370.07 Wh kg^(-1)and favorable cycling stability yard outperform BaVO,pure V_(2)O_(5),and many reported cathodes of similar ionic intercalation compounds.In addition,pseudocapacitance analysis,galvanostatic intermittent titration(GITT)tests,and Trasatti analysis revealed the high capacitance contribution and Zn^(2+)diffusion coefficient of CaVO,while an in-depth investigation based on EIS elucidated the reasons for the better electrochemical performance of CaVO.Notably,ex-situ XRD,XPS,and TEM tests further demonstrated the Zn^(2+)insertion/extraction and Zn-storage mechanism that occurred during the cycle in the CaVO//Zn battery system.This work provides new insights into the intercalation of similar divalent cations in vanadium oxides and offers new solutions for designing cathodes for high-capacity aqueous ZIBs.
基金This work was supported by the National Science Foundation(CBET-1803256)Dr.C.Liu acknowledges the support from National Natural Science Foundation of China(52102277)the Fundamental Research Funds for the Central Universities,conducted by Tongji University.
文摘Vanadium oxides,par-ticularly hydrated forms like V_(2)O_(5)·nH_(2)O(VOH),stand out as promising cathode candidates for aqueous zinc ion batteries due to their adjustable layered structure,unique electronic characteristics,and high theoretical capacities.However,challenges such as vanadium dissolution,sluggish Zn^(2+)diffusion kinetics,and low operating voltage still hinder their direct application.In this study,we present a novel vanadium oxide([C_(6)H_(6)N(CH_(3))_(3)]_(1.08)V_(8)O_(20)·0.06H_(2)O,TMPA-VOH),developed by pre-inserting trimethylphenylammonium(TMPA+)cations into VOH.The incorporation of weakly polarized organic cations capitalizes on both ionic pre-intercalation and molecular pre-intercalation effects,resulting in a phase and morphology transition,an expansion of the interlayer distance,extrusion of weakly bonded interlayer water,and a substantial increase in V^(4+)content.These modifications synergistically reduce the electrostatic interactions between Zn^(2+)and the V-O lattice,enhancing structural stability and reaction kinetics during cycling.As a result,TMPA-VOH achieves an elevated open circuit voltage and operation voltage,exhibits a large specific capacity(451 mAh g^(-1)at 0.1 A g^(-1))coupled with high energy efficiency(89%),the significantly-reduced battery polarization,and outstanding rate capability and cycling stability.The concept introduced in this study holds great promise for the development of high-performance oxide-based energy storage materials.
基金Supported by the National Natural Science Foundation of China(No.20171010).
文摘A new layered vanadium oxide [ NH3 （ CH2 ）2NH（ CH2 ）2NH3 ] [ V6O14 ] （ compound 1 ） was synthesized and characterized by elemental analysis, IR spectrometry and single crystal X ray diffraction. The compound crystallizes ina monoclinic space group P2（1）/n with a = 1.0254（2） nm, b =0.6739（2） nm, c = 1.2400（2） nm, ,8 = 93.88 （ 3 ） °, V = 0. 8549 （ 3 ）nm^3, Z = 2, R1 = 0. 0366, wR2 = 0. 1038. Compound 1 consists of two-dimensional mixed-valence vanadium oxide layers parallelling to the bc plane. The anti-tumor activity of the compound was estimated in three human tumor cell lines in vitro.
基金supported by the National Natural Science Foundation of China(22005268,51972286,21905246)Natural Science Foundation of Zhejiang Province(LQ20B010011,LR19E020003,LQ21E020004,and LZ21E020003)+2 种基金the Fundamental Research Funds for the Provincial Universities of Zhejiang Universities of Zhejiang(RF-B-2020004)support from the Leading Innovative and Entrepreneur Team Introduction Program of Zhejiang(2020R01002)supported by the National Key Research and Development Project of China(2022YFE0113800).
文摘Vanadium oxides are considered as one of the most promising cathode materials for aqueous zinc-ion batteries(ZIBs).However,the bulk morphology and strong electrostatic interaction between divalent Zn^(2+) and host materials inevitably cause an ultra-long activation process and poor performance.To address these issues,multiscale modification of commercial bulk V_(2)O_(5) was developed herein,which simultaneously optimized the valence states,interlayer spacing,and macrostructure in a facile one-step reduction process,resulting in a novel accordion-like V_(10)O_(24)·12H_(2)O.The synergistic effect of polyvalent vanadium,large interlayer spacing of 14.2Å,and unique open structure endowed V_(10)O_(24)·12H_(2)O with high electronic conductivity,rapid ion diffusion channels,and stable structure.A high specific capacity of 306.9 mA h g^(−1) and long durability for 1000 cycles with a capacity retention up to 81% was achieved when V_(10)O_(24)·12H_(2)O served as the cathode material for ZIBs.This multiscale modulation strategy demonstrates an effective and economical method for converting traditional vanadium oxides for use as highperformance cathodes for ZIBs.
基金support by Ulm University,the Helmholtz-Gemeinschaft(HGF)and the Deutsche Forschungsgemeinschaft(DFG)(STR 1164/12,STR1164/14 and Germany’s Excellence Strategy,EXC-2154/1)support through a PhD fellowship by the Fonds der Chemischen Industrie(FCI)the research performed at CELEST(Center for Electrochemical Energy Storage Ulm-Karlsruhe).
文摘Molecular vanadium oxides are promising active materials for cathodes in lithium and post-lithium batteries due to their high redox activity,low molecular weight and facile tuneability.However,a major challenge for this application is the transformation of the molecular clusters into solid-state oxides under typical electrode fabrication conditions.Here,we report a molecular crystal engineering approach for the stabilization of molecular vanadium oxides in the crystal lattice,enabling initial studies on reversible electron storage in a lithium ion battery test cell.
文摘Vanadium oxides with a layered structure are promising candidates for both lithium-ion batteries and sodium-ion batteries （SIBs）. The self-template approach, which involves a transformation from metal-organic frameworks （MOFs） into porous metal oxides, is a novel and effective way to achieve desirable electrochemical performance. In this stud~ porous shuttle-like vanadium oxides （i.e., V205, V203/C） were successfully prepared by using MIL-88B （V） as precursors with a specific calcination process. As a proof-of-concept application, the as- prepared porous shuttle-like VaOdC was used as an anode material for SIBs. The porous shuttle-like V203/C, which had an inherent layered structure with metallic behavior, exhibited excellent electrochemical properties. Remarkable rate capacities of 417, 247, 202, 176, 164, and 149 mAh.g-1 were achieved at current densities of 50, 100, 200, 500, 1,000, and 2,000 mA.g-1, respectively. Under cycling at 2 A.g-1, the specific discharge capacity reached 181 mAh.g-1, with a low capacity fading rate of 0.032% per cycle after 1,000 cycles. Density functional theory calculation results indicated that Na ions preferred to occupy the interlamination rather than the inside of each layer in the V203. Interestingly, the special layered structure with a skeleton of dumbbell-like V-V bonds and metallic behavior was maintained after the insertion of Na ions, which was beneficial for the cycle performance. We consider that the MOF precursor of MIL-88B （V） can be used to synthesize other porous V-based materials for various applications.
文摘Current research on vanadium oxides in lithium ion batteries （LIBs） considers them as cathode materials, whereas they are rarely studied for use as anodes in LIBs because of their low electrical conductivity and rapid capacity fading. In this work, hydrogenated vanadium oxide nanoneedles were prepared and incorporated into freeze-dried graphene foam. The hydrogenated vanadium oxides show greatly improved charge-transfer kinetics, which lead to excellent electrochemical properties. When tested as anode materials （0.005-3.0 V vs. Li/Li＋） in LIBs, the sample activated at 600℃ exhibits high specific capacity （-941 mA-h-g-1 at 100 mA.g-1） and high-rate capability （-504 mA·h·g-1 at 5 A·g-1）, as well as excellent cycling performance （-285 mA.h.g-1 in the 1,000th cycle at 5A-g-1）. These results demonstrate the promising application of vanadium oxides as anodes in LIBs.
基金supported by the National Research Foundation(NRF)for research conducted at the National University of Singapore(CRP No.NRF‐CRP26‐2021‐0003)the Singapore Ministry of Education(Tier 1,No.A‐8000186‐01‐00).
文摘Aqueous zinc‐ion batteries(ZIBs)are regarded as among the most promising candidates for large‐scale grid energy storage,owing to their high safety,low costs,and environmental friendliness.Over the past decade,vanadium oxides,which are exemplified by V2O5,have been widely developed as a class of cathode materials for ZIBs,where the relatively high theoretical capacity and structural stability are among the main considerations.However,there are considerable challenges in the construction of vanadium‐based ZIBs with high capacity,long lifespan,and excellent rate performance.Simple widenings of the interlayer spacing in the layered vanadium oxides by pre‐intercalations appear to have reached their limitations in improving the energy density and other key performance parameters of ZIBs,although various metal ions(Na+,Ca2+,and Al3+)and even organic cations/groups have been explored.Herein,we discuss the advances made more recently,and also the challenges faced by the high‐performance vanadium oxides(V2O5‐based)cathodes,where there are several strategies to improve their electrochemical performance ranging from the new structural designs down to sub‐nano‐scopic/molecular/atomic levels,including cation pre‐intercalation,structural water optimization,and defect engineering,to macroscopic structural modifications.The key principles for an optimal structural design of the V2O5‐based cathode materials for high energy density and fast‐charging aqueous ZIBs are examined,aiming at paving the way for developing energy storage designed for those large scales,high safety,and low‐cost systems.
基金This work was jointly supported by the Project of State Key Laboratory of Organic Electronics and Information Displays,Nanjing University of Posts and Telecommunications(Nos.GZR2022010017 and GDX2022010010)the National Natural Science Foundation of China(Nos.52102265 and 91963119)+2 种基金China Postdoctoral Science Foundation(No.2020M681681)Natural Science Foundation of Jiangsu Province of China(No.BK20210604)Nanjing University of Posts and Telecommunications Start-up Fund(Nos.NY220069 and NY220085).
文摘Vanadium oxides have attracted extensive interest as electrode materials for many electrochemical energy storage devices owing to the features of abundant reserves,low cost,and variable valence.Based on the in-depth understanding of the energy storage mechanisms and reasonable design strategies,the performances of vanadium oxides as electrodes for batteries have been significantly optimized.Compared to crystalline vanadium oxides,amorphous vanadium oxides(AVOs)show many unique properties,including large specific surface area,excellent electrochemical stability,lots of defects and active sites,fast ion kinetics,and high elasticity.This review gives a comprehensive overview of the recent progress on AVOs for different energy storage systems,such as alkali metal ion batteries,multivalent ion batteries,and supercapacitors with a special focus on the preparation strategies.The basic mechanisms for energy storage performance improvements of AVOs as compared to their crystalline counterparts are also introduced.Finally,challenges faced by AVOs are discussed and future development prospects are also proposed.This review aims to provide a comprehensive knowledge of AVOs and is expected to promote the development of high-performance electrodes for batteries.
基金financially supported by the Natural Science Foundations of Henan Province(Nos.222300420502 and 232300420093)the Program of Introducing Talents of Discipline to Universities(111 Project,No.D20015)+2 种基金the Key Scientific Research Projects in Higher Education Institutions of Henan Province(No.23ZX019)the Program for Science and Technology Innovation Talents in Universities of Henan Province(No.24HASTIT006)the Key Science and Technology Program of Henan Province(No.222102240044)
文摘The diverse valence and spatial structure endow vanadium oxides with significant potential in the field of aqueous zinc ion batteries(AZIBs).Although the conventional ion doping method mitigates the intrinsically sluggish kinetics,it exacerbates the erosion of Zn^(2+)/H^(+)and free water within the lattice structure,leading to inferior structural stability and capacity fading.Herein,a synchronous dual-modification strategy is introduced to improve the electrochemical performance of the V_(6)O_(13)cathode through an ingenious hydrolysis process involving K_(2)Cr_(2)O_(7).Experimental and calculated results demonstrate that the coating layer formed by chromium oxide supports the structural firmness and strengthens the interfacial chemistry,based on increased electrochemical activity by K^(+)intercalation.Consequently,the optimized sample delivers a capacity of 418 mAh g^(-1)at 0.1 A g^(-1),and excellent cyclic stability of 205 mAh g^(-1)after 6000 cycles at 10 A g^(-1).It is fully charged at a small current of 0.5 A g^(-1)to maintain a reversible capacity of 346 mAh g^(-1)after 72 h in an open circuit state,and there is no obvious capacity decay,highlighting the crucial protective effect of the inactive coating layer.This work presents a straightforward and reliable approach to effectively harmonize the relationship between activity and structural stability for advanced AZIBs cathode.
基金financially supported by the Science and Technology Research Program of Chongqing Municipal Education Commission(No.KJQN202300759)the Vanadium Titanium Materials Engineering Technology Research Center Foundation Project of Sichuan(No.2022FTGC07)+5 种基金the National Key R&D Program of China(No.2023YFC3009500)the National Natural Science Foundation of China(No.22379103)the Science and Technology Projects of Suzhou City(No.SYC2022043)the Campus Science Fund Project of Chongqing Jiaotong University(Nos.2020020086 and 2020023032)the Graduate Tutor Team Construction Project of Chongqing(No.JDDSTD2022006)the Graduate Student Research Innovation Project of Chongqing(No.2024S0110)
文摘The issue of water molecule activity in aqueous zinc-ion batteries presents a significant challenge.During the charging and discharging process,the strong polarity of water molecules tends to cause the dissolution of cathode materials,which reduces the cycle stability and specific capacity,consequently limiting the practical application of zinc-ion batteries.In this work,hydroxypropylβ-cyclodextrin(HP-β-CD),a special stereo cyclic organic molecule with hydrophobic inner cavity and hydrophilic outer cavity,is used as the intercalator for hydrated vanadium oxide(VOH)to enlarge the layer spacing and enhance the hydrophobicity of the cathode material.The larger interlayer spacing(13.9Å)of HP-β-CD-VOH is beneficial for improving ion mobility and the intrinsic electrochemical reaction kinetics.HP-β-CD-VOH delivers a discharge capacity of 336.7 mAh g^(-1)at 0.2 A g^(-1)and high-rate capability(242 mAh g^(-1)at 5 A g^(-1)).Due to the hydrophobic property of HP-β-CD in the interlayer pillar,the vanadium dissolution effect of polar water molecules can be reduced during charge and discharge;HP-β-CDVOH demonstrates sustained high efficiency and extended cycle longevity,maintaining a remarkable durability of 6000 cycles at a current density of 10 A g^(-1).This study presents an effective strategy for developing high-performance aqueous zinc-ion battery cathode materials.
基金financially supported by the National Natural Science Foundation of China(NSFC)(22171030 and 21771028)。
文摘Ni-ion aqueous batteries(NIBs)were considered an important development direction for aqueous batteries due to the high theoretical capacity(913 mA h g^(-1))and volume capacity(8136 mA h cm^(-3))of nickel metal.Herein,an electrolyte additive(dodecyl trimethyl ammonium chloride,DTAC)was used to improve the electrolyte environment,achieve efficient transport of Ni-ion,and combine the intercalated vanadium oxide cathodes to realize novel strategy NIBs.Firstly,the introduction of trace amounts of DTAC improved the high-concentration NiCl_(2)(4.2 M)electrolyte environment and reconstructed the hydrogen bond network.Molecular dynamics(MD)calculations and electrochemical results indicated that DTAC contributed to the desolvation process of Ni^(2+)and the realization of fast dynamics.The results of Ni symmetric cells demonstrated that DTAC enhanced the rapid migration of Ni-ion and achieved longer cycling stability(1750/1500 h at 0.2/0.5 mA cm^(-2)without obvious short circuits).Secondly,the insertion of organic small molecules(pyrrolidine)into vanadium oxide(V_(2)O_(5))to expand the interlayer spacing promoted the Ni-ion storage capacity of the cathodes.The capacity retention rate of Ni full battery after 6000 cycles at 5 A g^(-1)reached 82.17%.This work provided a novel strategy for the development of Ni-ion aqueous batteries.
基金funded by the Startup fund at Hubei University of Technology(Grant Nos.00709)a High-level Talent grant(Grant No.GCC2024012)from Hubei province.
文摘Pre-intercalation is the mainstream approach to inhibit the unpredicted structural degradation and the sluggish kinetics of Zn-ions migrating in vanadium oxide cathode of aqueous zinc-ion batteries(AZIBs),which has been extensively explored over the past 5 years.The functional principles behind the improvement are widely discussed but have been limited to the enlargement of interspace between VO layers.As the different types of ions could change the properties of vanadium oxides in various ways,the review starts with a comprehensive overview of pre-intercalated vanadium oxide cathode with different types of molecules and ions,such as metal ions,water molecules,and non-metallic cations,along with their functional principles and resulting performance.Furthermore,the pre-intercalated vanadium cathodes reported so far are summarized,comparing their interlayer space,capacity,cycling rate,and capacity retention after long cycling.A discussion of the relationship between the interspace and the performance is provided.The widest interspaces could result in the decay of the cycling stability.Based on the data,the optimal interspace is likely to be around 12?indicating that precise control of the interspace is a useful method.However,more consideration is required regarding the other impacts of pre-intercalated ions on vanadium oxide.It is hoped that this review can inspire further understanding of pre-intercalated vanadium oxide cathodes,paving a new pathway to the development of advanced vanadium oxide cathodes with better cycling stability and larger energy density.
基金National Natural Science Foundation of China(No.61376017)。
文摘Vanadium oxide(VO_(x))has garnered significant attention in the realm of resistive random-access memory(RRAM)owing to its outstanding resistive switching characteristics.However,the ambiguous mechanisms of resistive switching and inferior stability hinder its practical applications.Herein,an RRAM named VO_(x)/TiO_(2)/n^(++)Si device is prepared.It displays bipolar resistive switching behavior and shows superior cycle endurance(>200),a significantly high on/off ratio(>10^(2))and long-term stability.The tremendous improvement in the stability of the VO_(x)/TiO_(2)/n^(++)Si device compared with the Cu/VOx/n^(++)Si device is due to the p-i-n structure of VO_(x)/TiO_(2)/n^(++)Si.The switching mechanism of the VO_(x)/TiO_(2)/n^(++)Si device is attributed to the growth and annihilation of Cu conductive filaments.
基金supported by the National Natural Science Foundation of China(No.22179109).
文摘Although the enhancement of the zinc storage performance of layered vanadium oxides can be realized by the ionic pre-intercalation strategy,it also occupies a large number of active sites and thus fails to release the full potential of vanadium oxides.Here,vanadium oxide nanobelts with sodium-poor and oxygen defect-rich were constructed by regulating the content of pre-embedded sodium ions to strike a balance between pre-embedded ions and structural stability.The introduction of trace sodium ions not only increases the spacing of vanadium oxide layers but also occupies as few active sites as possible,which provides the possibility of massive storage,rapid diffusion and stabilization of the host structure for zinc ions.Moreover,the abundant oxygen defects transform the ion transport pathway from two-dimensional to three-dimensional,which greatly improves the ion transport rate in the host phase.Due to these advantages,the synthesized vanadium oxide nanobelts exhibit remarkable electrochemical properties,and this work provides a new idea for the design of structurally stable layered vanadium oxides with excellent properties.
基金financially supported by the Postgraduate Research&Practice Innovation Program of Jiangsu Province(No.KYCX23_3026)
文摘Vanadium-based materials are recognized as promising cathodes for high-energy-density aqueous zincion batteries(AZIBs).However,their inherent low intrinsic conductivities and sluggish reaction kinetics curtail their capacity release.Here,we enhanced the electron and ion transport properties of vanadium-based cathodes through heterojunction engineering,coupled with in situ electrochemical activation,significantly enhancing an unprecedented zinc-ion storage capacity and rapid kinetic performance.A heterostructured V_(2)O_(3)/g-C_(3)N_(4)(V_(2)O_(3)/CN)precursor was synthesized via a calcination process firstly.When employed as a cathode in AZIBs,this precursor undergoes an in situ phase transformation into Zn_(3)(OH)_(2-)V_(2)O_(7)-2H_(2)O/C_(3)N_(4)(ZVOH/CN)during the inaugural charging process,while retaining its heterojunction structure.Both electrochemical assessments and theoretical calculations revealed that ZVOH/CN exhibits superior zinc-ion adsorption and migration capabilities compared to conventional vanadium-based cathodes.The formation of the heterojunction amplifies the material's electronic conductivity and ion diffusion kinetics.As a result,the optimal ZVOH/CN composite electrode showcases a remarkable capacity of 518.5 mAh g^(-1)at 0.5 A g^(-1),superior rate performance of 177.8 mAh g^(-1)at 20 A g^(-1),and impressive cycling stability.This work offers a novel design strategy for vanadium-based composite materials as highperformance AZIB cathodes.
基金financially supported by the Research Project from the Chinese Ministry of Education (No. 213025A)
文摘Experiments comparing microwave blank roasting and conventional blank roasting for typical vanadium-bearing stone coal from Hubei Province in central China, in which vanadium is present in muscovite, were conducted to investigate the effects of roasting tempera- ture, roasting time, H2SO4 concentration, and leaching time on vanadium extraction. The results show that the vanadium leaching efficiency is 84% when the sample is roasted at 800℃ for 30 min by microwave irradiation and the H2SO4 concentration, liquid/solid ratio, leaching temperature, and leaching time are set as 20vo1%, 1.5：1 mL.g-1, 95℃, and 8 h, respectively. However, the vanadium leaching efficiency achieved for the sample subjected to conventional roasting at 900℃ for 60 min is just 71% under the same leaching conditions. Scanning electron microscopy （SEM） analysis shows that the microwave roasted samples contain more cracks and that the particles are more porous compared to the conventionally roasted samples. According to the results of X-ray diffraction （XRD） and Fourier-transform infrared （FTIR） analyses, neither of these roasting methods could completely destroy the mica lattice structure under the experimental conditions; however, both methods deformed the muscovite structure and facilitated the leaching process. Comparing with conventional roasting, microwave roasting causes a greater deformation of the mineral structure at a lower temperature for a shorter roasting time.
基金supported by the Fundamental Research(Discipline Arrangement)Project funding from Shenzhen Science and Technology Innovation Committee(Grant no.JCYJ20170412154554048)the Peacock Team Project funding from Shenzhen Science and Technology Innovation Committee(Grant no.KQTD2015033110182370)+3 种基金the National Key Research and Development Project funding from the Ministry of Science and Technology of China(Grants nos.2016YFA0202400 and 2016YFA0202404)the Shenzhen Maker Project for Students(Grant no.GRCK2017042410565958)the Guangdong Innovation Team Project(no.2013N080)the Shenzhen Peacock Plan(Grant no.KYPT20141016105435850)。
文摘Graphene is a type of promising electrode material for high-energy and high-power density supercapacitors,but its electrochemical performance is greatly limited by the restacking problem.In this work,we reported a facile approach to synthesis graphene with chemically bonded vanadium oxide(VOx)nanoparticles and demonstrated that chemically-bonded VOxnanoparticles can effectively prevent the graphene sheets from restacking and hence improve the electrochemical performance.The capacitance of VOxbonded graphene increases to 272 F/g compared to 183 F/g of pristine graphene in 1 M H3PO4 aqueous electrolyte at 2 A/g.The VOx-bonded graphene also showed improved rate capability in both H3PO4 and ionic liquid electrolytes.The capacitance retention increases to 54.5%from 28.5%at 100 A/g(compare to2 A/g)in H3PO4 and increases to 65.1%from 46.3%at 2 A/g(compare to 0.2 A/g)in neat ionic liquid.A high energy density of 84.4 Wh/kg is obtained within the voltage window of 4 V in ionic liquid.Even at a high-power density of 1000 W/kg,the VOx-bonded graphene shows a high energy density of 47.3 Wh/kg.
