Lithium Trivanadate Research Articles

Low-Temperature Synthesis of Polypyrrole-Coated LiV3O8 Composite with Enhanced Electrochemical Properties

A composite, -polypyrrole (PPy), was synthesized by a low-temperature solution route followed by an in situ polymerization method. The as-prepared powders consisted of nanosized PPy distributed homogeneously within the layered lithium trivanadate. The electrochemical properties of composite were systematically investigated and compared with bare lithium trivanadate. It was found that the electrochemical performance of the composite was significantly enhanced, with a specific capacity of retained after . This suggests that nanostructured PPy could work well as a polymer-conducting matrix and also as a binding material to improve the overall electrochemical properties of the when used as a cathode material in lithium-ion batteries.

Study on the silicon doped lithium trivanadate as cathode material for rechargeable lithium batteries

Silicon doped lithium trivanadate LiSi x V 3O 8 ( x = 0.000, 0.025, 0.050, 0.075, 0.100) were prepared via a solid state reaction and then aqueous redox reactions. The compositions, structures and electrochemical properties of the materials were intensively characterized by inductive coupled plasma atomic emission spectroscopy (ICP-AES), powder X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FTIR), cyclic voltammetry (CV) and galvanostatic charge–discharge cycle tests. The results show there are many advantages of the synthetic and modification method in this work such as simple elemental composition control. The structures of silicon doped samples behave readily for lithium transfer and intercalating/de-intercalating. The outstanding performances of the materials benefit from silicon doping significantly. LiSi 0.050V 3O 8 showed the best characteristics among the as-prepared materials. The specific discharge capacity of LiSi 0.050V 3O 8 remained 224.3 mAh·g − 1 at cycle 150 and 143.0 mAh·g − 1 at cycle 300 at a current density of 150 mA·g − 1 in the voltage range of 1.8–4.0 V.

Novel architecture of composite electrode for optimization of lithium battery performance

We show that the polymeric binder of the composite electrode may have an important role on the lithium trivanadate Li 1.2V 3O 8 electrode performance. We describe a new tailored polymeric binder combination with controlled polymer–filler (carbon black) interactions that allows the preparation of new and more efficient electrode architecture. Using this polymeric binder, composite electrodes based on Li 1.2V 3O 8 display a room temperature cycling capacity of 280 mAh g −1 ( C/5 rate, 3.3–2 V) instead of 150 mAh g −1 using a standard-type (poly(vinylidene fluoride)–hexafluoropropylene (PVdF–HFP) binder) composite electrode. We have coupled scanning electron microscopy (SEM) observations, galvanostatic cycling and electrochemical impedance spectroscopy in order to define and understand the impact of the microstructure of the composite electrode on its electrochemical performance. Derived from these studies, the main key factors that provide efficient charge carrier collection within the composite electrode complex medium are discussed.

A soft chemistry synthesis and electrochemical properties of LiV 3O 8 as cathode material for lithium secondary batteries

Lithium trivanadate, LiV 3O 8, was synthesized using rheological phase reaction method. First, the mixture of LiAc·2H 2O, NH 3VO 3, citric acid and a required amount of water reacted to form the rheological precursor, then the precursor was heated at different temperatures in the range of 350–600 °C and the product LiV 3O 8 was obtained. Thermogravimetric (TG) was employed to analyze the precursor. The LiV 3O 8 product which was characterized by inductively coupled plasma (ICP), X-ray diffraction (XRD) and scanning electron microscope (SEM) indicated that LiV 3O 8 has been obtained by this novel synthesis method. The influence of the preparing conditions including sintering temperature on crystal structure and electrochemical performance has been investigated. As a result, the LiV 3O 8 obtained at 400 °C for 10 h has excellent electrochemical properties. At 20 °C, the first discharge of which was 272.9 mAh/g in the range of 1.8–4.0 V at 0.3 mA cm − 2 . An inexpensive, simple and effective route to synthesis inorganic material was provided.

Improvement of lithium battery performance through composite electrode microstructure optimization

The lithium trivanadate Li1.2V3O8 has been investigated during the past decade as a very promising positive electrode material for lithium batteries due to its high theoretical capacity of 360 mAh/g. However, the experimental capacity remains generally much lower than (about half) the theoretical value. To increase electrode cycling performance in batteries, most researchers generally focus their work on the active material optimisation. Here we show that the polymeric binder of the composite electrode may have an important role on the electrode performance. We describe a new tailored polymeric binder combination with controlled polymer-filler (carbon black) interactions that allows the preparation of new and more efficient electrode architecture. Using this polymeric binder, composite electrodes based on Li1.2V3O8 display a room-temperature cycling capacity of 280 mAh/g (C/5 rate, 3.3-2V) instead of 180 mAh/g using a Bellcore-type composite electrode (PLIonTM technology). We have coupled SEM observations, galvanostatic cycling and electrochemical impedance spectroscopy in order to define and understand the impact of the microstructure of the composite electrode on its electrochemical performance. Derived from these studies, the main key factors that provide efficient charge carrier collection within the composite electrode complex medium will be discussed. Present findings open up new and attractive prospects for electrode performance optimisation.

Structure and properties of lithium trivanadate—a potential electroactive material for a positive electrode of secondary storage

Abstract Quantum-chemistry calculations were carried out to predict not only the structure, but also the energetic and electrical parameters of lithium trivanadates of the formulae Li1+xV3O8 (where x=1, 2 and 3). Altogether 21 entities were considered: four with the formula LiV3O8, 14 with the formula Li2V3O8 two with the formula Li3V3O8 and one with the formula Li4V3O8. A lithium–vanadium bronze with the formula Li1.3V3O8 was synthesised and investigated in order to compare experimental and predicted characteristics. The presence of Li1+xV3O8 units in the synthesised material was confirmed by infrared (IR) measurements. The predicted value of the open circuit voltage (OCV) change for the insertion of one lithium atom equal to 0.559 V compares well with the experimental value of 0.52 V for the insertion of the first lithium atom into the synthesised bronze. These results form the basis for predicting the properties and modelling or technologically interesting electroactive materials.

00/02594 Characteristics of vanadium based composite cathode for lithium secondary battery

A new treatment of has been proposed for improving its electrochemical behavior as a cathode material for secondary lithium batteries. Lithium trivanadate, , can be prepared in a finely dispersed form by dehydration of aqueous lithium trivanadate gels. The ultrasonic treatment method for Liv30s has been examined in comparison with prepared by solutionmethod. The ultrasonically treated products in water were characterized by XRD (X-ray diffractometry), TGA (thermogravimetric analysis) and SEM (scanning electron microscopy). These measurements showed that the ultrasonic treatment process of aqueous caused a decrease in crytallinity and considerable increased in specific surface area and interlayer spacing. The product, ultrasonically treated in water for 2 h, showed a high initial discharge capacity and was charge-discharge cycled without large capacity loss. The ultrasonic treated Liv30s can improve not only the specific capacity, but also the cycling behavior

Lithium insertion and extraction kinetics of Li1+xV3O8

Lithium insertion and extraction kinetics of lithium trivanadate, Li1+xV3O8, was investigated by using the electrochemical measurements at various temperatures and current densities. The results showed that the reaction rates of both insertion and extraction were limited by the small diffusivity of Li+ ions in the Li4V3O8 phase formed for x>1.5 upon lithiation. Extraction reaction was also dependent on the thermodynamic factor on the basis of the incomplete reversibility of transformation from the Li4V3O8 phase to the original LiV3O8 one.

Comparison of LiV3 O 8 Cathode Materials Prepared by Different Methods

Lithium trivanadate, , can be prepared in a finely dispersed form by dehydration of aqueous lithium vanadate gels. Two methods of dehydration, both easily adaptable to large‐scale production, are described in this work: freeze drying and spray drying. After heat‐treatment of the dried gels (xerogels) to remove loosely bound water they show a high capacity for lithium insertion, approaching four additional lithium per formula unit, and good reversibility as electrode materials for high energy density lithium cells. How the heat‐treatment temperature influences the crystal structure is demonstrated as well as the electrochemical properties of the vanadium oxide.

ChemInform Abstract: THE FORMATION OF METASTABLE POTASSIUM TRIVANADATE FROM MELTS

AbstractAus K20‐ VzOs‐Schmelzen durch langsames Abkühlen und/ oder schnelles Abschrecken erhaltene K‐Vanadate wurden durch IR‐Spektrometrie und Pulver‐X RD analysiert (V= O‐Valenzfrequenzen).

The Formation of Metastable Potassium Trivanadate from Melts

Abstract Potassium vanadates, which were prepared from melts by rapid quenching and slow cooling over the composition range of K2O-contents of C=(K)/(V)=0–0.50, were examined by means of IR spectrometry and X-ray powder diffraction. In the composition range of C≤0.17, mixtures of V2O5, K2V18O45, and K2V8O21 were produced by the slow cooling. At the composition of C=0.33, however, an unknown compound and K2V8O21 were the main products upon rapid quenching from melts, while at C=0.50 the main products were K3V5O14 and an additional unknown compound. The unknown compound was confirmed to be metastable and was formed as a single compound only by a rapid quenching from melts of K2O and V2O5 especially at C=0.37. The X-ray diffractions for the compound were characterized as d=8.2 (very strong), 4.05, and 3.27 Å, and the V=O stretching frequencies, as 995, 968, and 955 cm−1. By comparing these characteristic data with those of lithium trivanadate and sodium trivanadate (γ-phase), it was suggested that the unknown compound was isomorphous with trivanadate (M1+xV3O8).