Nickel Vanadate Research Articles

Synthesis and structure refinement studies of LiNiVO4 electrode material for lithium rechargeable batteries

The lithium nickel vanadate (LiNiVO4) cathode material has been synthesized by using sol-gel method. The thermal behavior of the material has been examined by thermogravimetric and differential thermal analysis (TG/DTA). The structure of LiNiVO4 compound has been studied by the Rietveld refined x-ray diffraction (XRD) technique. The Brunauer–Emmett–Teller (BET) surface area of 0.79 m2 g−1 was estimated with N2 absorption characteristics. The synthesized powder morphology was observed by field emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM). X-ray photoelectron spectroscopy (XPS) studies of synthesized LiNiVO4 powder indicate that the oxidation states of nickel and vanadate are +2 and +5, respectively. The electrochemical properties were monitored using 2032 coin cells by cyclic voltammetry and EIS, which showed that the microscopic structural features were deeply related with the electrochemical performance.

TEM characterization of Au-based alloys to join YSZ to steel for SOFC applications

The microstructures of two gold-based alloys with compositions (in wt.%) of 96.4Au-3Ni-0.6Ti and 97.5Au-0.75Ni-1.75V following oxidation at 850 Degree-Sign C for 200 min were characterized by analytical transmission electron microscopy with energy dispersive spectroscopy and by scanning electron microscopy. In the oxidized 96.4Au-3Ni-0.6Ti interlayer, a dense scale composed of nickel oxide (NiO) and nickel titanate (NiTiO{sub 3}) formed at the alloy surface. No evidence of titanium oxide was found because there was not enough Ti present to form titanium oxide. In the oxidized 97.5Au-0.75Ni-1.75V interlayer, loose vanadium oxide (V{sub 2}O{sub 5}) and nickel vanadate (Ni{sub 2}V{sub 2}O{sub 7}) formed and were distributed within the oxidized 97.5Au-0.75Ni-1.75V interlayer. Similarly, because of the low Ni content in the alloys, no NiO formed. The oxide products in the 96.4Au-3Ni-0.6Ti and 97.5Au-0.75Ni-1.75V interlayers after oxidation are consistent with the Pilling-Bedworth (PB) ratio considerations. - Highlights: Black-Right-Pointing-Pointer Two commercial Au-based reactive metallic interlayers were oxidized at 850 Degree-Sign C for 200 min. Black-Right-Pointing-Pointer The oxidized products at the surface were characterized by TEM/EDS and SEM. Black-Right-Pointing-Pointer NiO and NiTiO{sub 3} formed at the oxidized 96.4Au-3Ni-0.6Ti interlayer. Black-Right-Pointing-Pointer V{sub 2}O{sub 5} and Ni{sub 2}V{sub 2}O{sub 7} were found in the oxidized 97.5Au-0.75Ni-1.75V interlayer. Black-Right-Pointing-Pointer These oxidemore » products are consistent with the Pilling-Bedworth (PB) ratio considerations.« less

Mixed doped lithium nickel vanadate as cathode material by sol–gel and polymer precursor method

The mixed doped LiNi1−xMnxVO4 (0⩽x⩽1) has been synthesised by using sol–gel and polymer precursor methods. X-ray diffraction, thermogravimetric analysis/differential thermogravimetric analysis and scanning electron microscopy analyses have been carried out to study the structural and physical properties of the samples which can be used as the cathode material for lithium ion batteries. Citric acid was added during the sample preparation as the chelating agent. The prepared samples have been characterised thermally by thermogravimetric analysis/differential thermogravimetric analysis. The analysis shows few endothermic peaks at 80, 301, 371 and 573°C and this is due to the weight loss during the thermal process which corresponds to the inorganic and organic decompositions of the precursor. Scanning electron microscopy images show that the grain size of the composite samples increases with increasing temperature for the sample fired from 500 to 800°C, revealing a spherical shape of grain distribution at low temperature and a polyhedral shape at the highest sintering temperature. The size of the particle synthesised using both methods is also discussed in this work.

Sputtered lithium nickel vanadium oxide (LiNiVO4) films: Chemical compositions, structural variations, target history, and anodic/cathodic electrochemical properties

In this paper, we report the chemical compositional variations and target surface history of lithium nickel vanadate material during RF-magnetron sputtering. Amorphous films were characterized by nuclear methods [Rutherford backscattering spectroscopy (RBS) and nuclear reaction analysis (NRA)], Auger electron spectroscopy (AES), X-ray diffraction (XRD), scanning electron microscope (SEM), atomic force microscope (AFM), and high resolution transmission electron microscopy (HTEM) techniques. Various nanostructured/porous LiNiVO4 thin film materials were obtained, depending on the composition of films, total pressure, annealing temperatures, thickness and heating time. Optimum film composition was obtained with the sputtering parameters; oxygen partial pressure (Po2) = 10 mPa, total pressure of (PAr) = 1 Pa, Rf-power = 30 W. Cathodic and anodic electrochemical properties of LiNiVO4 films were evaluated by galvanostatic cycling at constant current and cyclic voltammetry electroanalytical techniques. Electrochemical performance of the LiNiVO4 film deliver a capacity of ∼780 mA hg−1 (10th cycle), potential range, 0.02–3.0 V (anodic), at a current rate, 75 μA cm−2. In the potential range 1.2–4.5 V, deliver a capacity of 280 mA hg−1, and in the potential window, 3.0–4.8 V (cathodic), 0.6 Li are removed from the host LiNiVO4 lattice.

Oxidative dehydrogenation of butenes over Ni-V-Sb/γ-Al2O3 oxide catalyst

The process of the oxidative dehydrogenation of butenes over a nickel-vanadium-antimony supported catalyst proceeds with a higher conversion and selectivity as compared to the dehydrogenation of n-butane. It was found that the maximum yield of divinyl per pass from the butylene fraction reaches 44% at a 68% selectivity. The maximum selectivity of the process (75%) is achieved at a divinyl yield of no more than 40%. The addition of nickel oxide to antimony vanadate results in the simultaneous formation of both nickel vanadate and antimonate, which are responsible for the conversion of butylenes to divinyl. Systems based on the supported Ni-V-Sb oxide matrix were analyzed with the use of the BET, X-ray photoelectron spectroscopy, diffuse reflection spectroscopy, X-ray diffraction, and hydrogen temperature-programmed reduction techniques. The formation of the NiV2O6 nickel vanadate phase results in the most selective catalyst with an increased amount of mobile oxygen in the lattice due to the presence of vanadium.

Surface acidic and redox properties of V-Ag-Ni-O catalysts for the selective oxidation of toluene to benzaldehyde

Abstract V-Ag-O and V-Ag-Ni-O complex oxides were found to exhibit good catalytic reactivity for the selective oxidation of toluene to benzaldehyde. In order to understand the effects of each metal in the two catalysts, a series of single and complex oxides were prepared including V 2 O 5 , Ag 2 O, NiO, V-Ni-O, Ag-Ni-O, V-Ag-O and V-Ag-Ni-O with the previously optimized compositions for the binary and tertiary oxides. Data from the X-ray diffraction (XRD), infrared spectroscopy and laser Raman spectroscopy showed the formation of complex oxides with phases of silver and nickel vanadates as well as the broadening and red shift of the band of V O bonds, suggesting the formation of V O Ag and V O Ni bonds and the increased redox ability of vanadium species. The results from temperature programmed reduction (TPR) and the combined technique of TPR-XRD revealed that the addition of Ag and Ni promoted the reduction of vanadium species in the complex catalysts. Microcalorimetric adsorption of ammonia and the probe reaction of isopropanol in air demonstrated that the surface acidity was greatly decreased while the redox cycles of vanadium sites were significantly enhanced upon the addition of Ag and Ni. The reactivity for the selective oxidation of toluene was evaluated by using a fixed-bed microreactor, and was correlated with the surface acidity and redox property of the catalysts. Silver seemed to be a special promoter that not only decreased the surface acidity but also enhanced the redox cycles of vanadium sites, leading to the increased conversion of toluene and the selectivity to benzaldehyde. Such effect was even more pronounced when Ag and Ni were added simultaneously. Accordingly, the V-Ag-Ni-O catalyst studied in this work exhibited excellent performance for the selective oxidation of toluene to benzaldehyde. The conversion of toluene was found to be 8% with 95% selectivity to benzaldehyde on the V-Ag-Ni-O at 613 K.

Preparation and characterization of LiNiVO 4 powder and non-stoichiometric LiNi xV yO z films

Inverse spinel type structured oxide, LiNiVO 4, was synthesized by using solid-state method and the crystalline powder was characterized by Rietveld refinement and X-ray photoelectron spectroscopy. Non-stoichiometric lithium nickel vanadate thin films were prepared by physical vapour deposition technique. The amorphous films were characterized by Rutherford back-scattering spectroscopy (RBS), nuclear reaction analysis (NRA), Auger electron spectroscopy (AES), X-ray diffraction (XRD), scanning electron microscopy (SEM) and high-resolution transmission electron microscopy (HRTEM) analytical methods. Films crystal growth at various temperatures was also studied by XRD and SEM. The HRTEM analysis of sputtered film shows nanocrystalline domains of NiO and LiNiVO 4 phases with characteristic lattice parameters of the host compound and the results correlate well with the XRD data. Electrochemical properties of the films were discussed.

Structural and electrochemical studies of annealed LiNiVO4 thin films

AbstractWe prepared stoichiometric lithium nickel vanadate amorphous thin films by using r.f. magnetron sputtering under controlled oxygen partial pressure. The amorphous films were heated at various temperatures, 300–600 °C, for 8 h. The as‐deposited and annealed thin films were characterized by Rutherford backscattering spectroscopy, nuclear reaction analysis, Auger electron spectroscopy, X‐ray diffraction, scanning electron microscopy and atomic force microscopy. The electrochemical behavior of the various films was studied by the galvanostatic method. The cells were tested in a liquid electrolyte at room temperature, with lithium metal used as the counter and reference electrode. The best electrochemical storage value was obtained with the thin film annealed at 300 °C, which showed superior capacity and small capacity loss during cycling. Copyright © 2007 John Wiley & Sons, Ltd.

A comparative study of structural and impedance spectroscopic analysis of LixMVO4 (M = Ni, Co; x = 0.8, 1.0, 1.2)

Lithium nickel vanadate and lithium cobalt vanadate with various lithium concentrations have been prepared by a solid-state reaction method. X-ray photoelectron spectroscopic analysis of both samples indicates a reduction in the oxidation state of vanadium with increasing lithium composition. Conductance spectra reveal the low coulombic repulsive force between lithium ions for Li1.0NiVO4 and Li1.2CoVO4. Modulus spectra indicate an increase in available sites for lithium motion with an increase in lithium content for both samples.

Effect of Substrate Temperature on Morphology and Electrochemical Performance of Radio Frequency Magnetron Sputtered Lithium Nickel Vanadate Films Used as Negative Electrodes for Lithium Microbatteries

Lithium nickel vanadate thin films were prepared by radio frequency magnetron sputtering at various substrate temperatures (Ts). These thin films have been investigated as anode electrode material in the use of microbatteries. Films were characterized by Rutherford backscattering spectroscopy, nuclear reaction analysis, Auger electron spectroscopy, glancing-incidence X-ray diffraction analysis, Raman spectroscopy, scanning electron microscopy, atomic force microscopy, and high-resolution transmission electron microscopy techniques. The anodic electrochemical performances of the films have been evaluated by cyclic voltammetry at a scan rate of 1 mV/s and by galvanostatic cycling, with lithium metal as the counter and the reference electrode, and cycled in the range of 0.02-3.0 V at a current density of 75 microA/cm2. Thin films prepared at a Ts of 650 degrees C show a discharge capacity at the 20th cycle of 1100 (+/-10) mAh/g, which exhibited excellent capacity retention with a small capacity fade.

Amorphous LiNiVO 4 thin-film anode for microbatteries grown by pulsed laser deposition

Thin films of lithium nickel vanadates are deposited by pulsed-laser deposition from targets with different lithium contents. The as-deposited films are mainly amorphous and possess smooth and dense surfaces as revealed by X-ray diffraction and scanning-electron microscopy. The initial loss in capacity between the first discharge and charge decreases with increase in the lithium content in the films. The film grown from the target of Li 1.2NiVO 4 gives the best performance with a retainable capacity as high as 410 μAh per cm 2 μm. There is almost no loss in capacity from the 11th up to the 50th cycle even though a fast decay occurs during the first several cycles. Cyclic voltammograms reveal cathodic peaks at 1.78 and 0.56 V and anodic peaks at 1.27 and 2.47 V, in line with the shapes of the discharge and charge curves.

Synthesis and structural analysis of lithium nickel vanadate

The compound Li x NiVO 4 ( x = 0.8; 1.0; 1.2) has been prepared by a solid state reaction method at 800 °C. The X-ray diffraction pattern of Li 1.2NiVO 4 shows the absence of the (1 1 1) line, indicating the occupation of more vanadium ions on the tetrahedrally coordinated interstices. The averaged size of the particles and the grain size have been found to be around 2–10 μm. The grain interior and grain boundary resistance values are found to be 4.08 × 10 5 and 1.45 × 10 6 Ω cm −1 at 573 K. The formal activation energy, describing the temperature dependence of conductivity of Li 0.8NiVO 4, was found to be 0.64 eV.

Vibrational analysis of lithium nickel vanadate

The compound Li X NiVO 4 ( X = 0.8, 1.0, 1.2) is prepared by a solid-state reaction method. The vibrational analysis of the compound is studied using Fourier transform infra red (FTIR) and Raman spectroscopic techniques. A new peak at 1039 cm −1 is observed for Li 1.2NiVO 4 in the FTIR analysis and indicates the presence of Li + O V bond interactions. The FTIR and Raman characteristic bands for cubic inverse spinel structure are observed for all samples. Using the diatomic approximation method, the bond length and the bond order of the compound with various Li compositions are calculated. The valence state of the compounds is calculated using the Pauling valence sum rule and is found to be nearly 5.2 for all compositions of Li X NiVO 4 ( X = 0.8, 1.0, 1.2).

Formation of nickel vanadates as a function of pH

The precise nature of the reaction between hydrochloric acid and sodium ortho-vanadate solution has been studied by means of electrometric techniques involving potentiometric and conductometric titrations. The well defined inflections and breaks in the titration curves confirm the existence of the anions, pyro-V2O74- , meta-VO3- and poly-H2V10O284- corresponding to the ratios of VO43-:H+ as 1:1, 1:2 and 1:2.6 in the neighborhood of pH 10.5, 7.4 and 3.6, respectively. The interaction of nickel chloride with sodium vanadate solutions, at specific pH levels 12.4, 10.5, 7.4 and 3.6 was also studied by potentiometric and conductometric titrations between the reactants. The end-points obtained from the sharp inflections in the titration curves provide definite evidence for the formation of ortho-3NiO.V2O5, pyro-2NiO.V2O5 and meta-NiO.V2O5 vanadates of nickel in the vicinity of pH 8.9, 8.0 and 6.8, respectively. Analytical investigations on the precipitates formed confirm the results of the electrometric study.

Oxidative conversion of isobutane to isobutene over V-Sb-Ni oxide catalysts

Insertion of proper amounts of nickel oxide into alumina-supported V-Sb oxide catalyst for the oxidative dehydrogenation of isobutane substantially increases isobutane conversion (from 36 to 42–44%) at selectivity to isobutene ∼70%. Fresh and used catalysts (including reference bulk V-Sb-O and V-Sb-Ni-O systems) were characterised by BET, XRD, XPS and H 2-TPR. Formation of new phase of nickel vanadate NiV 2O 6 at the expense of free VO x -phase leads to more reducible catalyst with increased amounts of mobile lattice oxygen. The facile redox cycle of vanadium species is considered to improve the catalyst activity.

LiNiVO 4–promising thin films for use as anode material in microbatteries

Thin films of lithium nickel vanadates (Li x NiV y O z ) have been prepared by radio frequency magnetron sputtering from a LiNiVO 4 target. The discharge gas was either pure argon or a mixture of argon and oxygen. The deposition rates as well as the composition and morphology of the films strongly depend on the sputtering parameters. For a total pressure of 1 Pa, the V/Ni atomic ratio varies between 0.75 for films developed in a pure argon plasma and 1.65 when the partial pressure of oxygen is 100 mPa. The thin film containing the two types of transition metals in an equiatomic ratio (Li 1.1NiVO 4) has given the best electrochemical properties as an anode displaying a specific capacity that became stable at 1000 mAh/g after three cycles, which is at least as high as for bulk material.

Amorphous Lithium Nickel Vanadate Thin-Film Anodes for Rechargeable Lithium Microbatteries

Sputter deposited lithium nickel vanadate thin films are investigated as a possible anode for lithium microbatteries. As-deposited films showed almost amorphous characteristics, but included a small amount of crystalline phase. The electrochemical behavior of thin-film electrodes exhibits consistent voltage charge curves for the first and subsequent cycles, and excellent cycling performance, which are different from the results obtained with bulk electrodes. These characteristics and a high specific capacity make lithium nickel vanadate thin films very attractive candidates for lithium rechargeable microbattery anodes.

Synthesis and electrochemical characteristics of Li–Ni vanadates as positive materials

An electrochemically active lithium–nickel vanadate phase of LiNiVO4 containing VO4 tetrahedrons has been synthesized by soft chemical method through a new mild liquid route at 450°C for 3 h in air. The products were characterized by X-ray diffraction, thermal analysis, SEM, IR and Raman spectra, respectively. The cells using lithium–nickel vanadate as a cathode can be cycled between 4.8 and 3.0 V (vs. Li) at current density of 0.2 mA/cm2. The results indicated that the low-temperature specimen prepared by liquid route exhibited better electrochemical properties than the high-temperature specimen obtained by solid-state reaction.

Electrochemical lithium insertion in some nickel, zinc and cadmium vanadates

Abstract In this work we present a study of the electrochemical characteristics of lithium insertion in eight crystalline Ni, Zn and Cd vanadates. During the electrochemical study carried out down to 0.5 V vs. Li + /Li, CdV 2 O 6 and Cd 2 V 2 O 7 were found to be the compounds tested accepting the highest number of lithium atoms per metal atom (Li/∑M=1.75 and 1.63, respectively). The zinc and nickel vanadates tested accepted a smaller number of lithium atoms per formula unit. In situ X-ray diffraction experiments showed an almost complete amorphization of the cadmium vanadates at the end of the first discharge while nickel and zinc vanadates were not amorphous. Therefore, these results are in agreement with previous reports of larger lithium atom intake in amorphous than in crystalline materials. In any case, on cycling none of these vanadates perform as well as previously described vanadium compounds.

XPS, auger, electrical and optical studies of vanadium phosphate glasses doped with nickel oxide

X-ray photoelectron and X-ray excited Auger spectra, optical absorption and DC conductivity of vanadium phosphate glasses containing nickel oxide have been studied as a function of nickel content. The shift in the binding energy of the V 2 p 3 2 photoelectron peak with the change in nickel content provided evidence of a change in the valence states of vanadium. The Ni 2 p 3 2 core level in NiO powder is a doublet and is normally used as a fingerprint for NiO. However, a single peak, shifted to higher binding energy, was observed in the glasses. The Ni (LVV) Auger spectrum for NiO powder showed a doublet structure. In glasses, however, two well-separated peak were observed in this spectrum. The results suggest that Ni in the glass may exist in two different phases, viz. nickel oxide and nickel vanadate. Initial addition of nickel (2 wt% of NiO) increased the optical absorption and electric conductivity but large additions, (5 wt% of NiO) led to a small decrease. The conductivity had a minimum value for a concentration of about 10 wt% of NiO. An attempt has been made to account for the observed changes in optical and electrical properties in terms of the XPS and Auger results.