Characterization Of LiFePO4 Research Articles

Synthesis and Characterization of LiFePO4 By Variation Addition Of (Li3PO4)0.5(AgI)0.25(LiI)0.25 as Cathode Material For All-Solid-State Li-ion Battery

The safety of lihium-ion batteries have always been a concerned for industrial application. Therefore, there is a strong interest to produce an all-solid-state battery. An all-solid-state battery has several advantages, including easy fabrication, non-flammable, low leakage, but mainly because it is safer. In this study, (Li3PO4)0.5(AgI)0.5(LiI)0.25 was synthesized as solid electrolyte. Meanwhile, as cathode, LiFePO4 was added by variations of: 0%, 10%, and 30% of (Li3PO4)0.5(AgI)0.5(LiI)0.25 to minimize the presence of solid state interface between solid electrolyte and cathode. The samples were characterized using Scanning Electron Microscope (SEM), X-Ray Diffraction (XRD), and conductivity measurement. For SEM images, the particle distribution was not thoroughly homogeneous because it was prepared manually by only grinding the samples. The X-ray data showed that (Li3PO4)0.5(AgI)0.5(LiI)0.25 has halo pattern and the crystal structure of synthesized cathode belongs to P m n a space group (Olivine Structure). The range of measured AC conductivity was around 10−4 S/cm - 10−8 S/cm.

Spectroscopic characterization of LiFePO4 as cathode material for Li-ion battery prepared in the pulse thermo-acoustic reactor

Lithium iron phosphate (LiFePO4) is a cathode material for the rechargeable-lithium batteries. In this paper is presented a novel method of fabrication carbon-coated LiFePO4 in a pilot reactor built according to the principles of the thermo-acoustic burner of Helmholtz-type. Crystalline powder with a high percentage of LiFePO4 was synthesized by incomplete combustion, i.e. in the reductive atmosphere, and calcined at 700?C for 6 h. The obtained samples were characterized by X-ray diffraction, IR and Raman spectroscopy. The aim of this study was to demonstrate the production of the high-quality lithium-ion cathode material by the incomplete combustion. The synthesis of LiFePO4 is completed during calcination and an ordered structure is attained. Fast synthesis in the reactor (less than 2 s) is achieved due to the reduction in the size of reactant's particles and a huge number of collisions owing to their strong turbulent flow associated with explosive combustion.

Preparation and characterization of LiFePO4·xLi3V2(PO4)3 composites by two-step solid-state reaction method for lithium-ion batteries

LiFePO4·xLi3V2(PO4)3 (LFP·xLVP, x=0, 0.05, 0.1, 0.15, 0.2) composites were prepared by the two-step solid-state method. The structure, morphology and electrochemical properties were characterized by X-ray diffraction, scanning electron microscope, cyclic voltammetry, charge-discharge performance test and electrochemical impedance spectroscopy. It was indicated that composites were presented rough in surface of ball-like particles. Two phase of LFP and LVP combination improved electrochemical properties of LFP. The LFP·0.1LVP has the highest discharge capacity of 154mAh/g at 0.2C. Compared with LFP, the rate performance of the LFP·0.1LVP increased 13% and 8% at 1C and 10C after five cycles. It possessed excellent cycle life of 99.8% after 100 cycles at 1C especially. The all preparation process without any solvent addition was easy operation, energy saving and environmentally friendly.

Characterization of LiFePO4/C composite and its thermal stability by Mössbauer and XPS spectroscopy

AbstractThe powders of the /C composite have been synthesized using the sol–gel method. The binding energies of the Fe 2p, P 2p, and O 1s core level the of /C surface were determined by X‐ray photoelectron spectroscopy (XPS). The deconvolution of the Fe 2p core level XPS is associated with the Fe2+ and Fe3+ valence states of the composite. Chemical composition and phase transitions were investigated using Mössbauer spectroscopy in the temperature interval of 10–600 K. Thermal decomposition of the composite was observed at 550 K.

Synthesis and characterization of LiFePO4–carbon nanofiber–carbon nanotube composites prepared by electrospinning and thermal treatment as a cathode material for lithium‐ion batteries

ABSTRACTBinder‐free LiFePO4–carbon nanofiber (CNF)–multiwalled carbon nanotube (MWCNT) composites were prepared by electrospinning and thermal treatment to form a freestanding conductive web that could be used directly as a battery cathode without addition of a conductive material and polymer binder. The thermal decomposition behavior of the electrospun LiFePO4 precursor–polyacrylonitrile (PAN) and LiFePO4 precursor–PAN–MWCNT composites before and after stabilization were studied with thermogravimetric analysis (TGA)/differential scanning calorimetry and TGA/differential thermal analysis, respectively. The structure, morphology, and carbon content of the LiFePO4–CNF and LiFePO4–CNF–MWCNT composites were determined by X‐ray diffraction, high‐resolution transmission electron microscopy, Raman spectroscopy, scanning electron microscopy, and elemental analysis. The electrochemical properties of the LiFePO4–CNF and LiFePO4–CNF–MWCNT composite cathodes were measured by charge–discharge tests and electrochemical impedance spectroscopy. The synthesized composites with MWCNTs exhibited better rate performances and more stable cycle performances than the LiFePO4–CNF composites; this was due to the increase in electron transfer and lithium‐ion diffusion within the composites loaded with MWCNTs. The composites containing 0.15 wt % MWCNTs delivered a proper initial discharge capacity of 156.7 mA h g−1 at 0.5 C rate and a stable cycle ability on the basis of the weight of the active material, LiFePO4. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 43001.

A novel synthesis and characterization of LiFePO4 and LiFePO4/C as a cathode material for lithium-ion battery

A novel hydrothermal stripping technique is developed to synthesize pure LiFePO4 and LiFePO4/C cathode materials. The pure sample is directly synthesized by the cation exchange between the organic phase which is prepared with FeSO4·7H2O and naphthenic acid, and aqueous phase prepared with H3PO4 and LiOH. SEM exhibits that the primary sizes of the well-distributed LiFePO4 and LiFePO4/C particles are about 150 nm and 100 nm in diameter, respectively. TEM indicates the LiFePO4/C is uniformly coated with a carbon layer about 2.7 nm in size. The as-prepared LiFePO4 exhibits a high initial discharge capacity of 135.5 mAh g−1 at 0.1 C, and the LiFePO4/C composite sintered at 650 °C for 4 h exhibits the best electrode properties with discharge capacities of 151.7, 154.8, 149.8 and 139.1 mAh g−1 at 0.1 C, 0.2 C, 0.5 C and 1.0 C rates, respectively. In addition, the LiFePO4/C also shows excellent capacity retention and cycle performances.

Shape Controlled Hydrothermal Synthesis and Characterization of LiFePO<SUB>4</SUB> for Lithium Ion Batteries

Various LiFePO4 microstructures were synthesized via hydrothermal or solvothermal routes using different additives. In an aqueous solution, LiFePO4 spindles whose length was about 2 microm were obtained with the assistance of polyvinyl pyrrolidone (PVP). As PVP and P2O7(4-) added in water, ellipsoidal LiFePO4 particles which composed of nanoparticles around 100 nm in diameter were obtained. If the additive was cetyltrimethyl ammonium bromide (CTAB), sheet-like LiFePO4 crystals with the width of 100 nm were prepared. In the mixed solvents of water together with ethanol or acetylacetone, when adding CTAB or polyethylene glycol (20000), LiFePO4 plates or nanoparticles were obtained. The ellipsoidal LiFePO4 had the best electrochemical properties among all these products. It is found that the annealed samples were significantly better than the corresponding unannealed ones. Take the ellipsoidal LiFePO4 for example, the initial discharge capacity of annealed (161 mAh/g) was much higher than the unannealed ones (85 mAh/g) at 0.1 C and the former cell still could deliver a capacity of 143 mAh/g after 30 cycles.

Synthesis and Characterization of LiFePO<SUB>4</SUB>/Al/C Composite Cathode Material

Synthesis and Characterization of LiFePO<SUB>4</SUB>/Al/C Composite Cathode Material

Synthesis and Characterization of LiFePO<sub>4</sub>-C/ PANI Composite for Cathode Material of Lithium Ion Battery

In-situ polymer coated LiFePO4-C composite material has been synthesized using different oxidizing agents viz. (NH4)2S2O8, KMnO4 and K2Cr2O7. Polyaniline (PANI) with chains having diameter ≤ 200 nm have been grown separately by self oxidation process of aniline monomers using the above oxidizing agents. For the synthesis of LiFePO4-C active material, initially raw material FePO4/PANI has been synthesized by chemical precipitation method and added with LiCOOCH3 followed by heat treatment at 700°C under reducing (Ar/H2=90/10) atmosphere for 16 hrs. The synthesized LiFePO4-C material has particle size of about 100 nm. The polymer coated LiFePO4-C composite was synthesized by undergoing in-situ polymerization of aniline monomers added with fixed quantity of LiFePO4-C. XRD analysis reveals formation of single phase pure active material LiFePO4-C and mixed phase containing LiFePO4 to FePO4 for polymer coated LiFePO4-C composite. The carbon content in the LiFePO4-C was estimated to be 5 wt%, however, the PANI content in the composites was different with different oxidizing agent. These PANI contents in the composites synthesized with (NH4)2S2O8, KMnO4 and K2Cr2O7 are 14, 15 and 17 wt% respectively which have been estimated by thermal gravimetric analysis (TGA) of the materials. Electrical conductivities of the composite materials were determined by Impedance spectroscopy method. The composite material synthesized with (NH4)2S2O8 has higher conductivity compared to those synthesized with KMnO4 and K2Cr2O7. The higher conductivity of the composite synthesized with (NH4)2S2O8 may be attributed to the presence of partial chain structure in polymer coating as seen by microstructural observations on the composite.

Synthesis and Characterization of LiFePO<sub>4</sub> Prepared by Sol-Gel Technique

LiFePO4 material was synthesized at 650°C in an N2 atmosphere using a sol-gel method. This material showed a well developed XRD pattern (orthorhombic structure, Pnma) without peaks at 2θ=41°, indicating the absence of FeP or metallic Fe2P impurities. The Li/LiFePO4 cell showed a high initial discharge capacity of more than 140mAh/g and no capacity decrease until the 50th cycle (>99.0%).

Characterization of LiFePO4/C Cathode for Lithium Ion Batteries

LiFePO4/C was synthesized from a mixture of different precursors of Li, Fe, and C by solid-state reaction. The initial mixture obtained was heated in different calcination conditions under inert atmosphere. The precursor of LiFePO4 doped with carbon was studied using different techniques such as thermal analysis, chemical and physical characterizations, and Mösbauer spectroscopy. A calculation of the crystallinity of the final product with two different methods is also presented. The chemical analysis techniques used were IRTF, XRD, and SEM. This characterization confirmed that we obtained a well-crystallized LiFePO4/C in all the operating conditions tested. The SEM showed aggregation and sintering during the calcination process, which were confirmed by the particle-size distribution measurements and by the physical characterizations. Mösbauer spectroscopy was used to determine the quantity of Fe(II) and Fe(III) contained in the final product. Our calcination conditions did not significantly modify the quantity of the two oxidation states.

Synthesis and characterization of LiFePO 4 and LiFePO 4/C cathode material from lithium carboxylic acid and Fe 3+

Olivine LiFePO 4 and LiFePO 4/C are successfully prepared by a simple solid-state reaction using FePO 4·2H 2O, lithium oxalate and glucose (bare LiFePO 4 without adding glucose) as raw materials. The structure of the LiFePO 4 and LiFePO 4/C is investigated by X-ray diffraction (XRD). The micromorphology of LiFePO 4 and LiFePO 4/C is observed using scanning electron microscopy (SEM) and BET, and the in situ coating of carbon on the particles is observed by transmission electron microscopy (TEM) and Raman spectrum. Furthermore, the electrochemical properties are evaluated by cyclic voltammograms (CVs), electrochemical impedance spectra (EIS) and constant current charge/discharge cycling tests. The results show that carbon coated LiFePO 4 can deliver better battery performance than the bare LiFePO 4. It exhibits initial discharge capacities of 162, 142 and 112 mA h g −1 at rates of 0.1, 1 and 10 C, respectively, and it presents excellent capacity retention as there is tiny capacity fade after 100 cycles. Moreover, the reductive mechanism of using lithium carboxylic acid to synthesize LiFePO 4 is firstly mentioned.

Synthesis and Characterization of LiFePO4 with Well Organized Microstructures

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Mo¨ssbauer Characterization of LiFePO4: Theoretical Aspects

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Preparation and characterization of LiFePO4/graphene-oxide composites

AbstractLiFePO4/graphene-oxide (GNO) composites were prepared by co-precipitation method. Their structure and morphology were investigated by X-ray diffraction, Fourier transform infrared spectra, field emission scanning electron microscopy, and transmission electron microscopy. A low content of GNO can be uniformly dispersed in the matrix of LiFePO4 nano particles, while at a higher content, GNO will aggregate severely and has a negative effect on the electrochemical performance of LiFePO4. Further heat treatment can improve the crystallinity of LiFePO4, and improve the electrochemical performance of LiFePO4 with a relatively low content of GNO.

Synthesis, electrochemical properties, and characterization of LiFePO 4/C composite by a two-source method

LiFePO 4/C composites were synthesized by a solid state reaction method utilizing two-component mixture of FeC 2O 4·2H 2O and LiH 2PO 4. Sintering the reactants with C 12H 22O 11 at different temperatures above 650 °C yields a product containing Fe 2P as a secondary phase to olivine LiFePO 4. The LiFePO 4/Fe 2P/C composite synthesized at 750 °C exhibits an excellent electrochemical performance, i.e. a discharge capacity of 152 mAh/g with a smooth plateau of 3.37 V and a good cycle performance at 0.2C charge/discharge current rate. Other detection techniques, such as X-ray absorption near edge structure (XANES) and scanning electron microscopy (SEM), were also carried out to characterize the sample.

ChemInform Abstract: Characterization of LiFePO4 at Nanoscopic Scale in Relation to the Mode of Preparation

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Synthesis and Characterization of LiFePO4/C Composite Obtained by One-Step Solid-State Reaction Using Solid PVA as Carbon Source

AbstractLiFePO4/C composite cathode materials were synthesized by one-step solid-state reaction using FePO4 as main raw materials and solid PVA (Polyvinyl Alcohol) as a reductive agent and carbon source. The sample was characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), particle size analysis and charge-discharge test. The results indicated that the carbon generated from the pyrogenation of PVA did not affect the olivine structure of the cathode materials but considerably improved its high-rate discharge ability and cycle performance. The initial discharge capacity of the sample was 149.7, 133.1, 120.6, 93.0 mAh/g at 0.2C, 1C, 2C, 5C respectively, and the discharge capacity could reach 90 mAh/g at 5C rates after 80 cycles. It is believed that the carbon coating could lead to small particle size and high electronic conductivity of active materials, thus leading to excellent electrochemical performance of LiFePO4/C cathode materials.

Synthesis and Characterization of LiFePO4 Nanoparticle/Mesoporous Carbon Composites as High-Power Cathode Materials for Lithium-Ion Batteries

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Synthesis and characterization of LiFePO 4/C composite obtained by sonochemical method

Lithium iron phosphate has become of great interest as storage cathode for the next generation of rechargeable lithium batteries. Olivine structure LiFePO 4/C composite powder was prepared by ultrasound assisted synthesis. A polyvinyl alcohol solution was used as the source of an in situ formed carbon. X-ray powder diffraction confirmed the phase purity. X-ray powder diffraction data were used for the crystal structure refinement, based on Rietveld full profile method. All relevant structural and microstructural crystal parameters that could be significant for electrochemical intercalation/deintercalation processes were determined. The Rietveld refinement also showed additional electron density on the lithium sites, indicating 3 at.% iron on the lithium site. Electrochemical characteristic of the composite was evaluated by using galvanostatic charge/discharge tests. While cycling at C/3 (C/10) rate the discharge capacity increases, starting from the value of 94.1 (116.0) mAh/g and reaching 99.5 (124.0) mAh/g at the end of the cycling. Particle morphology was revealed by both scanning and transmission electron microscopies. On the thin particle edges carbon film with a typical thickness of several nanometers can be observed, as well as small carbon agglomerates (typical size < 6 nm) at certain spots on the substrate surface.