Lithium Nickel Vanadate Research Articles

Effect of crystallite size on the intercalation pseudocapacitance of lithium nickel vanadate in aqueous electrolyte

This work describes lithium nickel vanadate (LiNiVO4) as a pseudocapacitor electrode material for the first time. The micro and nano-sized LiNiVO4 are synthesized via mechanochemical reaction and hydrothermal reaction followed by calcination, respectively. The phase purity, surface morphology and microstructure of the LiNiVO4 synthesized by both methods are analysed by X-ray diffraction and scanning electron microscopy techniques. The lithium ion intercalation-extraction behaviour of the LiNiVO4 electrode material is investigated in 1 M LiOH electrolyte solution. The results demonstrate an improved capacitive performance for nano-sized LiNiVO4 electrode synthesized via hydrothermal reaction due to the collective effect of small size and additional redox sites. The nanocrystalline LiNiVO4 electrode exhibits a high specific capacitance of 456.56 F g−1 at a current density of 0.5 A g−1. The cycle stability test reveals exceptional capacitance retention of 99.60% even after 1000 cycles owing to the unique structural feature which permit intercalation mechanism. These findings demonstrate the significance of lithium transition metal vanadate-based electrode material in the development of lithium ion intercalation pseudocapacitors.

Optical property and visible-light-driven photocatalytic activity of inverse spinel LiNiVO4 nanoparticles prepared by Pechini method

A new visible-light-driven and nano-sized photocatalyst was developed in the well-known cathode material of inverse spinel-type lithium nickel vanadate LiNiVO4. The nanoparticles were prepared by a modified Pechini method and characterized with the measurements such as X-ray diffraction (XRD), scanning electron microscope (SEM), Transmission electron microscopy (TEM), and UV–vis absorption spectrum. The photocatalytic activities of LiNiVO4 nanoparticles were evaluated by photodegradation of methylene blue (MB) under visible-light irradiation in air. LiNiVO4 nanoparticles showed an excellent photocatalytic activity duo to an efficient absorption in the UV–visible light wavelength region with a narrowed band gap energy of 2.10eV and an indirect allowed electronic transition. These results indicate that this pyrovanadate could be a potential photocatalyst driven by visible-light. The effective photocatalytic activity was discussed on the base of the crystal structure.

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.

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.

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.

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).

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.