Electrochemical Properties Of Li3V2 Research Articles

Preparation and electrochemical properties of Li3V2(PO4)3 glass-ceramic materials

The monoclinic lithium vanadium phosphate (Li3V2(PO4)3, LVP) is a promising cathode material for lithium-ion batteries due to its high theoretical specific capacitance, high operating voltage, good ionic conductivity, and thermal stability. However, synthesizing the pure LVP phase requires complicated procedures, expensive equipment, and long processing times. Moreover, the pure LVP phase has poor electrical conductivity, limiting its electrochemical properties and application. This study investigated the effect of glass preparation methods (single-crucible and double-crucible) and carbon coating on the crystalline phase, surface morphology, electrical conductivity, and electrochemical properties. A highly crystalline pure LVP phase can be synthesized effectively through heat treatment of the glass powder produced using the double crucible method at 700°C under a 5% H2-95% Ar atmosphere for 2 h. Adding C6H12O6 as a carbon source could increase the reducing atmosphere, preventing the oxidation of V3+ to V4+ and inhibiting the formation of the LiVOPO4 phase. This is beneficial for the synthesis of the pure LVP phase.Furthermore, the formation of an amorphous, uniform carbon coating on the surface of the LVP inhibits grain growth and increases the specific surface area. The CR2032 coin cell made with the LVP added with 10 wt% C6H12O6 had the highest initial discharge specific capacitance of 159.07 mAh g-1, with a specific capacitance retention rate of 77.31% even after 50 cycles. These findings suggest that LVP powder prepared using the double crucible method with carbon coating has the potential as a high-performance cathode material for lithium-ion batteries.

Effect of carbon coating on electrochemical properties of Li3V2(PO4)3 cathode synthesized by citric-acid gel method for lithium-ion batteries

Effect of carbon coating on electrochemical properties of Li3V2(PO4)3 cathode synthesized by citric-acid gel method for lithium-ion batteries

Li3V2(PO4)3/Li3PO4 Cathode Materials for Li-Ion Batteries: Synthesis and Characterization

Li3V2(PO4)3/Li3PO4 (LVPO/LPO) composites as cathodes for Li-ion batteries were synthesized by the hydrothermal method and subsequently annealed in an Ar atmosphere. The effect of Li3PO4 content on the crystal structure, morphology and the related magnetic and electrochemical properties of Li3V2(PO4)3/Li3PO4 composites, containing 7.5 wt% and 14 wt% of Li3PO4 (LVPO/LPO-7.5 and LVPO/LPO-14) was investigated. The microstructure and morphology of the obtained composites were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM); magnetic and electrochemical properties investigations were performed using the electron spin resonance and galvanostatic methods, respectively. It was shown that Li3V2(PO4)3/Li3PO4 composites exhibit a high discharge capacity, good cycle performance (105 and 120 mAh g−1 for the 200th cycle at 1C for LVPO/LPO-7.5 and LVPO/LPO-14, respectively), and insignificant changes in the surface morphology after 200 lithiation/delithiation cycles. Our results demonstrate that the increase in Li3PO4 content led to a decrease in the Li stoichiometry and magnetic inhomogeneity in Li3V2(PO4)3 phase; thus, the improvement in the electrochemical performance of LVPO/LPO composites due to incorporation of Li3PO4 can be attributed to their chemical and magnetic inhomogeneity.

Effect of chelating agents on the electrochemical performance of Li3V2(PO4)3/C composite

Lithium-ion batteries (LIBs) have a promising application prospect for energy storage systems due to its high energy and power density. To promote LIBs using Li3V2(PO4)3 as the cathode material, research on the modification of Li3V2(PO4)3 materials has become a hot topic. Among them, the carbon coating of Li3V2(PO4)3 is a simple and effective solution. Herein, the influence of experimental conditions on the physical and electrochemical properties of Li3V2(PO4)3/C composites was explored by the hydrothermal method. Due to the unique carbon coating, it can not only improve the conductivity of LVP, but also buffer the volume expansion. As expected, under the condition of a high rate of 30 C, the specific discharge capacity is 44.494 mA h/g when the voltage range is 3.0–4.8 V. Overall, considering the facile preparation strategy and unique structure, the Li3V2(PO4)3/C composite is a promising candidate for the Li-ion batteries.

Effects of nickel-doping on the microstructure and electrochemical performances of electrospun Li3V2(PO4)3/C fiber membrane cathode

Metal ion-doping and fibrosis treatment are important ways to improve the conductivity of lithium vanadium phosphate (Li3V2(PO4)3) electrode materials. However, the traditional casting preparation method could reduce the electronic and ionic conductivities of Li3V2(PO4)3 electrodes. In this work, the nickel (Ni)-doped Li3V2(PO4)3/C nanofiber membrane with a three-dimensional network structure was prepared by an electrospinning technique, which was directly used for self-standing cathodes in lithium-ion batteries. The effects of Ni-doping on the morphology, structure, and electrochemical properties of Li3V2(PO4)3/C nanofiber membrane were studied. The results show that the Ni-doping not only changes the crystal structure and morphology of Li3V2(PO4)3/C fibers, but also affects the electrochemical performances of the Li3V2(PO4)3/C electrodes. 1‰ Ni-doping has slightest effect on the crystal structure compared with other ratios, and the catalytic effect of Ni nanoparticles makes Li3V2(PO4)3/C grow directionally to form a hybrid membrane containing Li3V2(PO4)3/C nanofibers and Li3V2(PO4)3/C nanowires. The hybrid membrane electrode possesses good electrochemical performances at the current densities of 1C and 5C owing to the long-range continuous electron conductive networks, high porosity to favor the electrolyte permeation and Li-ion transport, and stable integrated-electrode structure to enhance the redox reaction. This self-standing Li3V2(PO4)3/C nanofiber membrane cathode is expected to be used in high-energy lithium-ion batteries.

Unraveling the Relationship between Ti4+ Doping and Li+ Mobility Enhancement in Ti4+ Doped Li3V2(PO4)3

The electrochemical properties of Li3V2(PO4)3 (LVP) cathode of lithium ion batteries are often improved by ion doping. Nevertheless, the mechanism of ion doping has not been fully understood. Here, Ti4+ has been chosen as a typical dopant with similar atomic radius to the 6-coordinated V3+. A series of Li3TixV(2-x)(PO4)3/C samples are successfully synthesized by a sol-gel route. The 7Li MAS NMR spectra of the LTxVP/C demonstrate that the doping of Ti4+ can enhance the mobility of Li ions. The results of electrochemical properties tests show that moderate Ti4+ doping is able to improve the high rate capability of the materials by increasing the electronic conductivity and Li-ion diffusion coefficient. The optimal sample (LT0.08VP/C) exhibits the best cycling behavior and rate capability, which can deliver 110.85 mAh/g and capacity retention of 99.36% at 10 C after 100 cycles. Electrochemical impedance spectroscopy results indicate that LT0.08VP/C possesses the minimum charge transfer resistance. The calcul...

Synthesis and electrochemical properties of Li3V2 (PO4)3-V2O3/C as anode material for lithium-ion battery application

The composites of Li3V2(PO4)3/C (noted as LVP/C) and Li3V2(PO4)3-V2O3/C (noted as LVP-V/C) are prepared by a rheological phase reaction (noted as RPR) process for anode material. The synthesized samples are measured by the X-ray diffraction (XRD) technique. The content of the carbon in the composite is detected by the thermogravimetric (TG) analysis. The morphologies of powders are observed by the scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The electrochemical properties of the samples as anode material are tested by the battery testing system. The LVP-V/C composite behaved better electrochemical performances than those of LVP/C as an anode material. The reasons that LVP-V/C behaved outstanding electrochemical properties are discussed also. Based on its electrochemical performances, the LVP-V/C composite may be a potential anode material for rechargeable lithium batteries.

Silicon and its effect on the electrochemical properties of Li3V2(PO4)3 cathode material

In this study, silicon and its effect on the properties of Li3V2(PO4)3 were studied for lithium-ion battery applications. The composite material was synthesized and found to show enhanced capacity and cyclability. The presence of silicon in the composites was confirmed. Furthermore, large particles with rough, corroded-like structures formed, and these were distributed well with the silicon particles. The Li3V2(PO4)3-Si battery had good properties showing improved cyclability, an improved high performance rate, smaller impedance values and improved lithium-ion diffusion coefficients, as determined by cyclic voltammetry. Furthermore, the optimization of the silicon content led to a Li3V2(PO4)3-Si battery with a 2 wt% silicon loading that had a discharge capacity of 181 mA h g−1. At 2 C, Li3V2(PO4)3-Si (2 wt%) still demonstrated a capacity of 111.8 mA h g−1, which was 83.8% of its original capacity (compared with 70.3 mA h g−1 and 63.8% for Li3V2(PO4)3) after 400 cycles.

Influence of Adipic Acid on Electrochemical Properties of Li3V2 (PO4)3 as Cathode Material for Rechargeable Lithium-Ion Batteries

Influence of Adipic Acid on Electrochemical Properties of Li3V2 (PO4)3 as Cathode Material for Rechargeable Lithium-Ion Batteries

Impact of carbon coating thickness on the electrochemical properties of Li3V2(PO4)3/C composites

A series of Li3V2(PO4)3/C composites with different amounts of carbon are synthesized by a combustion method. The physical and electrochemical properties of the Li3V2(PO4)3/C composites are investigated by X-ray diffraction, element analysis, Raman spectroscopy, scanning electron microscopy, transmission electron microscopy and electrochemical measurements. The effects of carbon content of Li3V2(PO4)3/C composites on its electrochemical properties are conducted with cyclic voltammetry and electrochemical impedance. The experiment results clearly show that the optimal carbon content is 4.3 wt %, and more or less amount of carbon would be unfavorable to electrochemical properties of the Li3V2(PO4)3/C electrode materials. The results would provide some basis for further improvement on the Li3V2(PO4)3 electrode materials.

Preparation and Electrochemical Properties of Li₃V₂(PO₄)3-xBrx/Carbon Composites as Cathode Materials for Lithium-Ion Batteries.

Li3V2(PO4)3−xBrx/carbon (x = 0.08, 0.14, 0.20, and 0.26) composites as cathode materials for lithium-ion batteries were prepared through partially substituting PO43− with Br−, via a rheological phase reaction method. The crystal structure and morphology of the as-prepared composites were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM), and electrochemical properties were evaluated by charge/discharge cycling and electrochemical impedance spectroscopy (EIS). XRD results reveal that the Li3V2(PO4)3−xBrx/carbon composites with solid solution phase are well crystallized and have the same monoclinic structure as the pristine Li3V2(PO4)3/carbon composite. It is indicated by SEM images that the Li3V2(PO4)3−xBrx/carbon composites possess large and irregular particles, with an increasing Br− content. Among the Li3V2(PO4)3−xBrx/carbon composites, the Li3V2(PO4)2.86Br0.14/carbon composite shows the highest initial discharge capacity of 178.33 mAh·g−1 at the current rate of 30 mA·g−1 in the voltage range of 4.8–3.0 V, and the discharge capacity of 139.66 mAh·g−1 remains after 100 charge/discharge cycles. Even if operated at the current rate of 90 mA·g−1, Li3V2(PO4)2.86Br0.14/carbon composite still releases the initial discharge capacity of 156.57 mAh·g−1, and the discharge capacity of 123.3 mAh·g−1 can be maintained after the same number of cycles, which is beyond the discharge capacity and cycleability of the pristine Li3V2(PO4)3/carbon composite. EIS results imply that the Li3V2(PO4)2.86Br0.14/carbon composite demonstrates a decreased charge transfer resistance and preserves a good interfacial compatibility between solid electrode and electrolyte solution, compared with the pristine Li3V2(PO4)3/carbon composite upon cycling.

Effects of chelating agents on the electrochemical properties of Li3V2(PO4)3/C cathode materials

The Li3V2(PO4)3/C cathode materials for lithium-ion batteries are synthesized by sol–gel method using three different compounds (citric acid, glycine and oxalic acid) as the chelating agents. The effects of chelating agents on the physical properties and electrochemical performances of the Li3V2(PO4)3/C composites are investigated by thermogravimetric analysis, infrared spectrometry, X-ray diffraction, scanning electron microscope and various electrochemical techniques. The results show the electrochemical properties of Li3V2(PO4)3/C prepared using citric acid as chelating agent are better. In the voltage range of 3.0–4.3 V (vs. Li+/Li), the citric acid chelated Li3V2(PO4)3 displays large reversible capacity with an initial discharge capacity of 126.7 mAh g−1 at 0.5 C, and 91.3% of the initial discharge capacity is retained after 50 charge–discharge cycles.

ChemInform Abstract: Lithium Vanadium Phosphate as Cathode Material for Lithium Ion Batteries

AbstractReview: 218 refs.

Electrochemical characterization for lithium vanadium phosphate with different calcination temperatures prepared by the sol–gel method

Li3V2(PO4)3/C (LVP/C) composite materials were synthesized via a sol–gel method with oxalic acid as the chelating agent and polyethylene glycol (PEG) as the supplementary carbon source. The oxalic acid and PEG serve as double carbon sources. This study focused on the effect of different calcination temperatures on the electrochemical properties of Li3V2(PO4)3. The diffraction peaks for all of the samples are well indexed to monoclinic Li3V2(PO4)3 with a P21/n space group. The TGA data indicate that the residual carbon content of LVP/C-700 is the highest (i.e., 2.31wt.%), and as the calcination temperature increased, the residual carbon content of the material gradually decreased. SEM and TEM analyses indicated that the LVP particles that were calcined at 700°C exhibit a uniform particle size distribution and the carbon coating exhibited a complete and orderly moderate thickness. The LVP/C-700 material exhibits the best electrochemical performance in the voltage range of 3.0 to 4.3V and 0.1C where the initial discharge capacity can reach 128.98mAhg−1. Even after 200cycles, the discharge capacity was 119.31mAhg−1, and the capacity retention rate was 92.49%.

Effects of chelating agents on electrochemical properties of Li3V2(PO4)3/C cathode materials

The Li3V2(PO4)3/C cathode materials for lithium ion batteries are synthesised by sol–gel method using three different compounds (citric acid, glycine and oxalic acid) as the chelating agents. The effects of chelating agents on the physical properties and electrochemical performances of the Li3V2(PO4)3/C composites are investigated by thermogravimetric analysis, infrared spectrometry, X-ray diffraction, scanning electron microscopy and various electrochemical techniques. The results show that the electrochemical properties of Li3V2(PO4)3/C prepared using citric acid as chelating agent are better. In the voltage range of 3.0–4.3 V (versus Li+/Li), the citric acid chelated Li3V2(PO4)3 displays large reversible capacity with an initial discharge capacity of 126.7 mAh g− 1 at 0.5°C, and 91.3% of the initial discharge capacity is retained after 50 charge–discharge cycling.

Lithium vanadium phosphate as cathode material for lithium ion batteries

Lithium vanadium phosphate (Li3V2(PO4)3) has been extensively studied because of its application as a cathode material in rechargeable lithium ion batteries due to its attractive electrochemical properties, including high specific energy, high working voltage, good cycle stability, and low price. In this review, the preparation of technology, structure, Li+ insertion/extraction mechanism, and electrochemical properties of Li3V2(PO4)3 are introduced, and with particular focus on the relationship of these topics each other. The synthetic techniques of Li3V2(PO4)3, such as high-temperature solid-state method, sol–gel method, hydrothermal method, etc. And progress of techniques in modification, such as coating and elemental doping, is reviewed. Finally, the directions for further development and prospective applications for the material are proposed.

Influences of La doping on magnetic and electrochemical properties of Li3V2(PO4)3/C cathode materials for lithium-ion batteries

Li3V2−xLax(PO4)3/C cathode materials have been successfully synthesized by a sol-gel method. The monoclinic structure of Li3V2(PO4)3 appeared in La doped samples which show enlarged unit cell volumes compared with the sample without La doping. The doping of La influences magnetic property of Li3V2(PO4)3/C, e.g. the magnetic susceptibility of Li3V2−xLax(PO4)3/C decreases rapidly with the increasing of La content. La doped composites exhibit better electrochemical property than that of the undoped one and the Li3V1.975La0.025(PO4)3/C displays the highest capacity and best cycle stability. The Li3V1.975La0.025(PO4)3/C presents the first discharge capacity of 122.4mAhg−1 at 1C rate in the voltage range of 3.0–4.3V, 15.7% higher than that of Li3V2(PO4)3/C. And there is no capacity loss after 50 cycles. The rapid Li+ diffusion and high structural stability due to the doping of La3+ are mainly responsible for the good electrochemical performance of La doped Li3V2(PO4)3/C cathode materials.

Impacts of synthesis temperature and carbon content on the electrochemical performances of the Li3V2(PO4)3/C composite synthesized by a polyol method

As a cathode material for Li-ion battery, Li3V2(PO4)3 was synthesized by a polyol method using LiOH·H2O, V2O5, NH4H2PO4, sucrose, and ethylene glycol as starting materials. Under the polyol process, the impacts of synthesis parameters, including the sintering temperature, holding time, and carbon content, on the morphological evolution and electrochemical properties of Li3V2(PO4)3 were investigated. The XRD results show the formation of pure Li3V2(PO4)3 with monoclinic crystal structure. The images of SEM show the similar-spherical morphology with uniform and optimized particles size, which greatly improves the electrochemical performance. The carbon coated on the Li3V2(PO4)3 particles was clearly observed by electron microscopy. The particle size of Li3V2(PO4)3 powders gradually decreases with the increase of carbon content in composite. In the potential range of 3.0–4.3 V, the composite synthesized at 800 °C for 10 h with 10% carbon content shows the highest discharge capacity of 128 mAh g−1 at 0.1C, which is nearly close to the theoretical capacity, and it remains fairly stable (more than 126 mAh g−1) even after the 20th cycles. Based on the results from the electrochemical impedance spectroscopy (EIS) analysis, the apparent diffusion coefficients of Li ions in the composite materials are between 1.82 × 10−10 and 3.79 × 10−9 cm2 s−1, which are much higher than those of olivine LiFePO4.

Li3V2(PO4)3 As a Positive Electrode Material for Rechargeable Lithium Batteries

Nowadays, demands lithium ion batteries which are mounted in portable devices increase day by day. As a result, research towards positive and negative electrode materials being intensively progressed. Most commonly used positive electrode is LiCoO2 because it has good electrochemical property. However, Co is rare material and it is placed in limited area. Therefore, price of Co increases more and more. To substitute Co, plenty of transition metal material is studied such as Fe, Ni, Mn and V. Among them polyanion phosphate material such as LiMPO4 (M = Fe, Co, Mn and etc) and Li3V2(PO4)3 are considered as possible candidate materials because of their structure, thermal stabilities and low price. However, those polyanion material, LiMPO4 (M = Fe, Co, Mn) has low energy density, causing low energy density. Li3V2(PO4)3 has good safety as LiFePO4 but higher energy density than LiFePO4 because of its high redox potential, V2+/5+. Also, Li3V2(PO4)3 has high reversible capacity and high theoretical capacity (197 mAh g-1). In this paper, physical and electrochemical properties of Li3V2(PO4)3 is investigated.Li3V2(PO4)3 is synthesized by solid state method. Stoichiometric amount of Li2CO3, NH4H2PO4, and V2O5 powders were grind and mixed by ball mill. The mixed powders were calcined at 500 oC in air atmosphere. The calcined powders were pelletized and sintered at 800 oC for 5 h in reduction atmosphere again. The calcinations, heated pellets were grind in Ar filled glove box to avoid air exposure. The synthesized Li3V2(PO4)3 powders were identified by X-ray diffraction (XRD) with Cu Kα radiation and analyzed by Rietveld refinement. Electrochemical test were carried out in coin type cell. Galvanostatic electrochemical charge and discharge test were made between 3.0 V and 4.8 V at 10 mA g-1 current at room temperature. The XRD pattern of the product shows single phase Li3V2(PO4)3 were obtained without impurity. The galvanostatic charge and discharge performances of Li3V2(PO4)3 as an positive electrode are tested in voltage range of 3.0 V and 4.8 V. Also to understand the mechanism during charge and discharge, ex-situ XRD, XPS and ToF-SIMS measurement were carried out at the first cycle. Furthermore to understand the affect the thermal stability high temperature XRD and TGA were carried out. Details will be discussed in the conference site.

Effects of Nd-doping on the structure and electrochemical properties of Li3V2(PO4)3/C synthesized using a microwave solid-state route

Abstract Nd-doped Li 3 V 2 − x Nd x (PO 4 ) 3 /C (x = 0, 0.01, 0.02, 0.04, 0.06 and 0.08) cathode materials are successfully and fast synthesized by a microwave solid-state route. The effects of Nd-doping on the structure and electrochemical properties of Li 3 V 2 (PO 4 ) 3 /C are investigated. Compared with the X-ray diffraction (XRD) pattern of the undoped sample, these Nd-doped samples have no extra reflections, which indicate that Nd enters the structure of the Li 3 V 2 (PO 4 ) 3 /C cathode. Scanning electron microscope (SEM) images show that Nd-substitution in Li 3 V 2 (PO 4 ) 3 /C has regular and uniform particles. According to the results of charge/discharge measurements at 0.1 C rate, the initial capacities of the Nd-doped samples are all higher than that of the undoped sample which is 140 mAh g − 1 . Among all the doped samples, Li 3 V 1.96 Nd 0.04 (PO 4 ) 3 /C shows the best rate capability and cycling stability. The initial discharge capacity of Li 3 V 1.96 Nd 0.04 (PO 4 ) 3 /C is 157 mAh g − 1 with the capacity retention ratio of 92.5% after 50 cycles at 0.1 C. Especially, it still shows a high discharge capacity of 126 mAh g − 1 even at a higher rate of 5.0 C. Electrochemical impedance spectroscopy (EIS) reveals that the charge transfer resistance of as-prepared samples is reduced through Nd-substitution and its reversibility is enhanced as proved by the cyclic voltammograms (CV). The improved electrochemical properties of Nd-doped Li 3 V 2 (PO 4 ) 3 /C can be attributed to the optimizing particle size and structural stability due to the proper amount of Nd-doping in V sites.