Alpha-CuV2O6 nanowires: hydrothermal synthesis and primary lithium battery application

We report on the synthesis, characterization, and electrochemical lithium intercalation of alpha-CuV2O6 nanowires, mesowires, and microrods that were prepared through a facile hydrothermal route. The diameters of the as-synthesized alpha-CuV2O6 nanowires, mesowires, and microrods were about 100 nm, 400 nm, and 1 microm, respectively. It was found that by simply controlling the hydrothermal reaction parameters, such as the reagent concentration and the dwell time, the transformation of microrods to nanowires was readily achieved via a "ripening-splitting" mechanism. Electrochemical measurements revealed that the as-prepared alpha-CuV2O6 nanowires and mesowires displayed high discharge capacities (447-514 mAh/g at 20 mA/g and 37 degrees C) and excellent high-rate capability. In particular, the alpha-CuV2O6 nanowires showed capacities much higher than those of alpha-CuV2O6 mesowires, microrods, and bulk particles. The mechanisms for the electrochemical lithium intercalation into the alpha-CuV2O6 nanowires were also discussed. From the Arrhenius plot of lithium intercalation into alpha-CuV2O6 nanowires, the activation energies were calculated to be 39.3 kJ/mol at 2.8 V (low lithium uptake) and 35.7 kJ/mol at 2.3 V (high lithium uptake). This result indicates that the alpha-CuV2O6 nanowires are promising cathode candidates for primary lithium batteries used in long-term implantable cardioverter defibrillators (ICD).     

The Ag2O-V2O5-HF((aq)) system and crystal structure of alpha-Ag3VO4

Reactions between the three components Ag2O, V2O5, and HF(aq) were investigated under hydrothermal conditions, and the recovered phases were, in increasing Ag:V content, Ag2V4O11, beta-AgVO3, Ag4V2O6F2, Ag4V2O7, and alpha-Ag3VO4. A higher ratio of Ag2O to V2O5, as compared to a stoichiometric ratio, was required to synthesize Ag4V2O6F2, Ag4V2O7, and alpha-Ag3VO4. Owing to their solubility differences, the crystallization regions are not centered around the respective 2:1 and 3:1 Ag2O/V2O5 tie-lines but rather are centered along the 4:1 and 8:1 Ag2O/V2O5 tie-lines. Reactions with a 4:1 Ag/V ratio either resulted in Ag4V2O6F2 at 150 degrees C or Ag4V2O7 at 200 degrees C. Products were recovered in between 80% and 100% yield based on V2O5. Red transparent crystals of alpha-Ag3VO4 crystallize in the monoclinic space group C2/c, with cell parameters a = 10.1885(16) A, b = 4.9751(8) A, c = 10.2014(17) A, beta = 115.754(3) degrees .     

CoV2O6纳米线／微米棒的制备及其在锂离子电池中的应用

采用水热法制备了纳米线／微米棒结构的CoV2O6电极材料,并探讨了纳米线／微米棒的形成机理．通过XRD、BET、SEM、TEM／HRTEM等测试手段对合成产物的结构、形貌、组成、表面性质进行了表征,结果表明,水热条件例如反应温度、反应时间对于产物的结构和形貌起关键作用．在220℃,水热反应1h可以得到直径为60nm的CoV2O6纳米线,而在220℃,水热反应6h可以得到直径10μm的CoV2O6微米棒．研究了CoV2O6纳米线／微米棒作为锂离子电池负极材料的电化学性能,结果显示,与CoV2O6微米棒相比,CoV2O6纳米线具有高的初始放电容量（1235mAh/g）和较好的循环稳定性,CoV2O6纳米线有希望作为锂离子电池的负极材料．     

Ag4V2O6F2: an electrochemically active and high silver density phase

Low-temperature hydrothermal techniques were used to synthesize single crystals of Ag(4)V(2)O(6)F(2). This previously unreported oxide fluoride phase was characterized by single-crystal X-ray diffraction and IR spectroscopy and was also evaluated as a primary lithium battery cathode. Crystal data: monoclinic, space group P2(1)/n (No. 14), with a = 8.4034(4) A, b = 10.548(1) A, c = 12.459(1) A, beta = 90.314(2) degrees , and Z = 4. Ag(4)V(2)O(6)F(2) (SVOF) exhibits two characteristic regions within the discharge curve, an upper plateau at 3.5 V, and a lower sloped region around 2.3 V from reduction of the vanadium oxide fluoride framework. The material has a nominal capacity of 251 mAh/g, with 148 mAh/g above 3 V. The upper discharge plateau at 3.5 V is nearly 300 mV over the silver reduction potential of the commercial primary battery material, Ag(2)V(4)O(11) (SVO).     

NiCo2O4纳米线对 H2O2电还原的催化性能

以无模板生长法制备了泡沫镍载NiCo2O4纳米线正极材料, XRD和SEM表征结果表明, 所得材料为NiCo2O4纳米线, 以循环伏安法和计时电流法研究了泡沫镍载NiCo2O4纳米线对H2O2电还原的催化性能. 结果显示, 在0.4 mol/L H2O2 和 3.0 mol/L NaOH 溶液中, 当电压为-0.4 V(vs. Ag/AgCl)时, 循环伏安的电流密度达到125 mA/cm2; 当电压为-0.2, -0.3和 -0.4 V 时, 在30 min 的测试时间内, 计时电流密度几乎均为一常数, 表明以泡沫镍载NiCo2O4纳米线为催化剂电还原H2O2具有很高的活性和很好的稳定性.     

Self-coiling of Ag2V4O11 nanobelts into perfect nanorings and microloops

Free-standing Ag2V4O11 nanorings and microloops have been synthesized by a simple hydrothermal process without any template or surfactant. The Ag2V4O11 nanorings and microloops have preferred growth direction along the [30] plane and are formed by the self-rolling of Ag2V4O11 nanobelts.     

泡沫镍载 NiCO2O4电极的制备及其催化 H2O2电氧化的性能

本文以水热法结合热处理法原位制备了泡沫镍载 NiCo₂O₄纳米线电极,使用XRD、SEM和TEM对合成的 NiCo₂O₄纳米线进行了表征,NiCo₂O₄纳米线直径约80 nm,长度约 3 ~ 5 μm. 使用循环伏安和计时电流法测试了泡沫镍载NiCo₂O₄纳米线催化H₂O₂的电氧化性能,结果表明泡沫镍载NiCo₂O₄纳米线对H₂O₂电氧化有着优良的催化活性、稳定性和传质性能,在0.3 V电位下0.4 mol·L ^-1 H₂O₂和2 mol·L ^-1 NaOH溶液中氧化电流可达380 mA·cm ^-2.     

Selective synthesis and characterization of single-crystal silver molybdate/tungstate nanowires by a hydrothermal process

Selective synthesis of uniform single crystalline silver molybdate/tungstate nanorods/nanowires in large scale can be easily realized by a facile hydrothermal recrystallization technique. The synthesis is strongly dependent on the pH conditions, temperature, and reaction time. The phase transformation was examined in details. Pure Ag(2)MoO(4) and Ag(6)Mo(10)O(33) can be easily obtained under neutral condition and pH 2, respectively, whereas other mixed phases of Mo(17)O(47), Ag(2)Mo(2)O(7,) Ag(6)Mo(10)O(33) were observed under different pH conditions. Ag(6)Mo(10)O(33) nanowires with uniform diameter 50-60 nm and length up to several hundred micrometers were synthesized in large scale for the first time at 140 degrees C. The melting point of Ag(6)Mo(10)O(33) nanowires were found to be about 238 degrees C. Similarly, Ag(2)WO(4), and Ag(2)W(2)O(7) nanorods/nanowires can be selectively synthesized by controlling pH value. The results demonstrated that this route could be a potential mild way to selectively synthesize various molybdate nanowires with various phases in large scale.     

电池正极材料Li3V2(PO4)3/C的水热合成和性能

以LiOH·H2O, NH4VO3, NH4H2PO4 和麦芽糖等为原料, 采用水热法合成了碳包覆的磷酸钒锂化合物, 考察了碳含量对材料电化学性能的影响. 利用XRD, TEM, SEM和恒流充放电测试等手段对产物的结构、 形貌和电化学性能进行表征. 结果表明, 在650℃煅烧的样品为单一纯相的单斜晶体结构. 晶体颗粒分布为100~300 nm, 粒度分散均匀, 分散性良好, 无团聚现象, 且在颗粒表面包覆了一层无定形碳, 这有利于改善材料的导电率. 含碳量为10.23%的样品, 在倍率1.0C的电流密度下, 在3.0~4.3 V电压范围内, 样品的首次放电比容量高达118.8 mA·h/g, 循环15圈后放电比容量为115.1 mA·h/g, 容量保持率为96.88%.     

Ag4V2O6F2 (SVOF): a high silver density phase and potential new cathode material for implantable cardioverter defibrillators

The electrochemical reactivity of the cathode material Ag 4V 2O 6F 2 (SVOF) versus lithium, with a particular emphasis on the lithium insertion mechanism, was studied by means of the complementary techniques in situ X-ray diffraction, electron paramagnetic resonance, and high-resolution transmisssion electron microscopy. This study confirms the initial reports of a high capacity for SVOF of 148 mAh/g above 3 V and that the reduction of silver above 3 V (vs Li (+)/Li (0)) leads to a loss of SVOF crystallinity until it becomes completely amorphous between the third and fourth lithiums inserted. Next, vanadium is reduced between 2.5 and 1.5 V (vs Li (+)/Li (0)) for the fifth and sixth lithiums inserted. In addition, the polarization within the cathode is significantly lower for the vanadium reduction than for the silver reduction. The silver metal morphologies consisted of nanoparticles ( approximately 5 nm diameter) and dendrites and were both seen in samples of lithiated SVOF.     

Ag2V4O11: from primary to secondary battery

Journal of Solid State Electrochemistry - Ag2V4O11 (silver vanadium oxide, SVO) is the positive electrode in primary lithium/SVO batteries that had known an extraordinary success as a power source...     

Bismuth telluride (Bi2Te3) nanowires: synthesis by cyclic electrodeposition/stripping, thinning by electrooxidation, and electrical power generation

Nanowires composed of the thermoelectric material Bi2Te3 were synthesized on highly oriented pyrolytic graphite (HOPG) electrodes using the electrochemical step edge decoration (ESED) method. Nanowire synthesis was initiated by applying a voltage pulse of -0.75 V versus SCE for 5 ms to an HOPG electrode in an aqueous solution containing both Bi3+ and TeO22-, thereby producing nuclei at the step edges. Bi2Te3 was electrodeposited onto these nuclei using a cyclic electrodeposition-stripping scheme that involved the electrodeposition of bismuth-rich Bi2Te3 on a negative-going voltammetric scan (to -0.05 V) and the subsequent anodic stripping of excess bismuth from these nanowires during a positive-going scan (to +0.35 V). When this cycle was repeated 10-50 times, Bi2Te3 nanowires in the 100-300-nm-diameter range were obtained. These nanowires were narrowly dispersed in diameter (RSDdia = 10-20%), were more than 100 microm in length, and were organized into parallel arrays containing hundreds of wires. Smaller nanowires, with diameters down to 30 nm, were obtained by electrooxidizing 150-nm-diameter Bi2Te3 nanowires at +0.37 V under conditions of kinetic control. This oxidation process unexpectedly improved the uniformity of Bi2Te3 nanowires, and X-ray photoelectron spectroscopy (XPS) shows that these nanowires retain a Bi2Te3 core but also have a thin surface layer composed of Bi and Te oxides. The ability of Bi2Te3 nanowires to generate electrical power was assessed by transferring ensembles of these nanowires onto cyanoacrylate-coated glass surfaces and evaporating 4-point nickel contacts. A dimensionless figure of merit, ZT, ranging from 0 to 0.85 was measured for fresh samples that were less than 1 day old. XPS reveals that Bi2Te3 nanowires are oxidized within a week to Bi2O3 and TeO2. These oxides may interfere with the application by evaporation of electrical contacts to these nanowires.     

Mesoporous nickel oxide nanowires: hydrothermal synthesis, characterisation and applications for lithium-ion batteries and supercapacitors with superior performance

Mesoporous nickel oxide nanowires were synthesized by a hydrothermal reaction and subsequent annealing at 400?°C. The porous one-dimensional nanostructures were analysed by field-emission SEM, high-resolution TEM and N(2) adsorption/desorption isotherm measurements. When applied as the anode material in lithium-ion batteries, the as-prepared mesoporous nickel oxide nanowires demonstrated outstanding electrochemical performance with high lithium storage capacity, satisfactory cyclability and an excellent rate capacity. They also exhibited a high specific capacitance of 348?F?g(-1) as electrodes in supercapacitors.     

四元尖晶石相Li——M——Mn——O(M=Ni,Cr,Mo,V)嵌入电极的研究

制备了用不同价态的几种金属阳离子(Ni2^+,Cr3^+,V5^+,Mo6^+)修饰的尖晶石LiMn~2O~4嵌入化合物作为锂二次电池的阴极材料,对Li/LiM~yMn~2~-~yO~4电池进行了电化学和X射线衍射研究.结果表明,其它离子的掺杂使标准尖晶石LiMn~2O~4电极对锂的反复脱嵌和嵌入有了更强的承受力,但在不同程度上降低了其初始容量.循环性能的提高归于掺杂的金属阳离子使尖晶石结构趋于更稳定.同时还讨论了修饰离子对尖晶石相在充放电时5V电压平台出现的影响。     

Reactivity Control of CH Bond Activation over Vanadium-Silver Bimetallic Oxide Cluster Cations

Vanadium-silver bimetallic oxide cluster ions (V(x) Ag(y) O(z) (+) ; x=1-4, y=1-4, z=3-11) are produced by laser ablation and reacted with ethane in a fast-flow reactor. A reflectron time of flight (Re-TOF) mass spectrometer is used to detect the cluster distribution before and after the reactions. Hydrogen atom abstraction (HAA) reactions are identified over VAgO(3) (+) , V(2) Ag(2) O(6) (+) , V(2) Ag(4) O(7) (+) , V(3) AgO(8) (+) , V(3) Ag(3) O(9) (+) , and V(4) Ag(2) O(11) (+) ions, in which the oxygen-centered radicals terminally bonded on V atoms are active sites for the facile HAA reactions. DFT calculations are performed to study the structures, bonding, and reactivity. The reaction mechanisms of V(2) Ag(2) O(6) (+) +C(2) H(6) are also given. The doped Ag atoms with a valence state of +1 are highly dispersed at the periphery of the V(x) Ag(y) O(z) (+) cluster ions. The reactivity can be well-tuned gradually by controlling the number of Ag atoms. The steric protection due to the peripherally bonded Ag atoms greatly enhances the selectivity of the V-Ag bimetallic oxide clusters with respect to the corresponding pure vanadium oxide systems.     

Synthesis of high-density nanocavities inside TiO2-B nanoribbons and their enhanced electrochemical lithium storage properties

Single crystalline TiO2-B nanoribbons with high-density nanocavities were successfully synthesized via a simple hydrothermal route. The as-prepared TiO2-B nanoribbons exhibited a large Brunauer, Emmett, and Teller (BET) surface area of about 305 m(2)/g because of the high-density nanocavities inside the thin nanoribbons. Electrochemical measurements indicated that the TiO2-B nanoribbons with dense nanocavities showed discharge specific capacity higher than those of TiO2-B nanotubes and nanowires. It was found that the dense nanocavities have an important influence on the electrochemical lithium intercalation properties.     

花状NH4V4O10微纳米结构的水热制备及电化学嵌锂性能

通过水热法制备了花状NH4V4O10微纳米结构. 采用XRD,SEM,TEM,XPS等测试手段对样品结构、形貌和组成进行了表征. 实验结果表明,所制得的NH4V4O10花状结构是由直径约100 nm,长度为几微米的纳米带团簇而形成. 研究了反应体系中温度、时间等因素对NH4V4O10产物形貌的影响. 将制备的NH4V4O10组装成锂模拟扣式电池,考察了其电化学嵌锂性能. 研究结果显示,所制备的花状NH4V4O10具有较高的比容量（307 mAh?g-1）,有望作为锂离子电池的新型正极材料.     

Mesoporous Nickel Oxide Nanowires: Hydrothermal Synthesis,Characterisation and Applications for Lithium‐Ion Batteries and Supercapacitors with Superior Performance

Mesoporous nickel oxide nanowires were synthesized by a hydrothermal reaction and subsequent annealing at 400 °C. The porous one‐dimensional nanostructures were analysed by field‐emission SEM, high‐resolution TEM and N₂ adsorption/desorption isotherm measurements. When applied as the anode material in lithium‐ion batteries, the as‐prepared mesoporous nickel oxide nanowires demonstrated outstanding electrochemical performance with high lithium storage capacity, satisfactory cyclability and an excellent rate capacity. They also exhibited a high specific capacitance of 348 F g^?1 as electrodes in supercapacitors.     

锂离子电池复合正极材料xLiFePO4·yLi3V2(PO4)3的复合机制

以FePO4·xH2O、V2O5、NH4H2PO4和Li2CO3为原料, 以乙二酸为还原剂, 通过湿化学还原-低温热处理方法制备出锂离子复合正极材料xLiFePO4·yLi3V2(PO4)3. X射线衍射(XRD)结果表明, 合成的材料中橄榄石结构的LiFePO4和单斜晶系的Li3V2(PO4)3两相共存; 从复合材料中LiFePO4、Li3V2(PO4)3相对于相同条件下制备的纯相LiFePO4和Li3V2(PO4)3的晶格常数变化以及结合高分辨透射电子显微镜(HRTEM)、能量散射X射线(EDAX)的结果可以看出, 在复合材料xLiFePO4·yLi3V2(PO4)3中存在部分V和Fe, 分别掺杂在LiFePO4和Li3V2(PO4)3中, 并形成固溶体; X射线光电子能谱(XPS)结果表明, Fe/V在复合材料中的价态与各自在LiFePO4和Li3V2(PO4)3中的价态保持一致, 分别为+2 和+3价. 充放电测试表明, 制备出的复合正极材料电化学性能明显优于单一的LiFePO4和Li3V2(PO4)3; 循环伏安测试表明, 复合正极材料具有优良的脱/嵌锂性能.     

Constructing Co3O4 Nanowires on Carbon Fiber Film as a Lithiophilic Host for Stable Lithium Metal Anodes

Lithium metal has been considered as the most promising anode electrode for substantially improving the energy density of next‐generation energy storage devices. However, uncontrollable lithium dendrite growth, an unstable solid electrolyte interface (SEI), and infinite volume variation severely shortens its service lifespan and causes safety hazards, thus hindering the practical application of lithium metal electrodes. Here, carbon fiber film (CFF) modified by lithiophilic Co₃O₄ nanowires (denoted as Co₃O₄ Nws) was proposed as a matrix for prestoring lithium metal through a thermal infusion method. The homogeneous needle‐like Co₃O₄ nanowires can effectively promote molten lithium to infiltrate into the CFF skeleton. The post‐formed Co?Li₂O nanowires produced by the reaction of Co₃O₄ Nws and molten lithium can homogeneously distribute lithium ions flux and efficaciously increase the adsorption energy with lithium ions proved by density functional theory (DFT) calculation, boosting a uniform lithium deposition without dendrite growth. Therefore, the obtained composite anode (denoted as CFF/Co?Li₂O@Li) exhibits superior electrochemical performance with high stripping/plating capacities of 3 mAh cm^?2 and 5 mAh cm^?2 over long‐term cycles in symmetrical batteries. Moreover, in comparison with bare lithium anode, superior Coulombic efficiencies coupled with copper collector and full battery behaviors paired with LiFePO₄ cathode are achieved when CFF/Co?Li₂O@Li composite anode was employed.