Properties Of Lithium Iron Phosphate Research Articles

Influence of the nanogrinding process on the performance of lithium iron phosphate

Wet grinding is one of the most common forms of technology in powder production and preparation. Sand mill is the latest technology of wet grinding, which can effectively reduce the grinding particle size and improve the powder reactivity. LiFePO4 is one of the widely used cathode materials for lithium batteries at present, and the grinding process will affect the product performance. In this paper, parallel type and series type grinding processes were simulated by the single-cylinder system and the double cylinder system, which were studied and compared through the preparation of LiFePO4. It was discovered that the series type grinding process can not only increase the grinding efficiency but also improve the consistency of particle size distribution. LiFePO4 prepared by the series type grinding process has better rate performance and a higher discharge voltage platform. Attributing to the uniform particle size of LiFePO4, the lithium-ion diffusion coefficient was raised, which was proved by the cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). To sum up, based on the results of this paper, the properties of lithium iron phosphate will be affected by the particle size distribution, which is related to the grinding process. Therefore, in order to obtain the best performance of LiFePO4, it is necessary to choose the appropriate production process. This research work provides references and the basis for the research of powder grinding production technology.

Effect of polyvinyl pyrrolidone/sodium polyacrylate compound surfactants on slurry properties of lithium iron phosphate and electrochemical performance of the battery

Effect of polyvinyl pyrrolidone/sodium polyacrylate compound surfactants on slurry properties of lithium iron phosphate and electrochemical performance of the battery

Improved electrochemical performances and magnetic properties of lithium iron phosphate with in situ Fe2P surface modification by the control of the reductive gas flow rate

The growth of Fe2P was successfully regulated in the inner surface of LiFePO4 by the control of the reductive gas flow rate. The as-synthesized composites were characterized by XRD, XPS, TEM, and magnetic measurements. The experimental results indicated that the Fe2P content of the samples increases with the increasing reductive gas flow rate. Moreover, due to the effective conductive path from Fe2P, it was found that the moderate modified-Fe2P LiFePO4 sample had an excellent rate performance and cyclic stability under a high current density. It was also confirmed that LiFePO4 decorated with a moderate amount of Fe2P shows a lower charge transfer resistance and higher Li+ diffusion coefficient than that of the other samples examined in our investigation. However, excessive Fe2P modification had a negative effect on the enhancement of the electrochemical performance, which was mainly attributed to the large amount of available Fe2P; its non-electrochemical activity sacrifices the specific capacity of the LiFePO4 material. This work provides a novel method to obtain high performance by controlling the gas flow rate to optimize the amount of conducting Fe2P. Furthermore, the potential relationship between the LiFePO4 material’s electrochemical and magnetic properties was investigated. It was believed that the magnetic moment is a simple and sensitive method for detecting the electrochemical performances of LiFePO4 electrode materials.

Effect of Spherical Particle Size on the Electrochemical Properties of Lithium Iron Phosphate

The effect of spherical particle size on the surface morphology, electrochemical property and processability of lithium iron phosphate was systematically studied. Spherical lithium iron phosphate with different particle size distributions controlled with ball time of precursor slurry was prepared by spray drying method. The samples were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), charge and discharge measurements and EIS. The electrochemical performances of the sample materials were measured by coin cells and 14500 batteries. XRD shows that the spherical lithium iron phosphate with different particle sizes all have good crystal structure due to the perfect mixing of the raw materials and rapid drying. The lithium iron phosphate microsphere with different particle sizes self-assembled with submicron primary particles has a core-shell structure. The longer ball time the precursors are, the smaller the active material particles are prepared. The electrode material with 6 h ball time of precursor slurry has the best physical properties and the processability. The composite has a uniform particle size and higher tap density of 1.46 g/cm3, which delivers a discharge capacity of 167.6 mAh/g at a discharge rate of 0.5 C. The results were confirmed by the 14 500 mA·h cylindrical batteries, which delivers a discharge capacity of 579 mAh at 0.5 C. And low-temperature performance with capacity of 458.5 mA h at −20 °C under a discharge rate of 0.5 C is the 79.2% of the same discharge rate at 25 °C. Otherwise, the 14500 batteries also exhibit excellent cycling performance and the capacity maintains 93% after 2 000 cycles.

Properties of lithium iron phosphate prepared by biomass-derived carbon coating for flexible lithium ion batteries

This study highlights the effects of a biomass-derived carbon coating on the properties of flexible lithium iron phosphate polymer batteries. Pure LiFePO4 (LFP) and carbon-coated LiFePO4 (C-LFP) cathode materials are synthesized by a modified mechanical activation process. LiFePO4 was uniformly coated with biomass-derived carbon by the addition of orange peel during the synthesis. C-LFP with a particle size of approximately 90 nm, having a homogeneous particle size distribution with particles smaller than that of pure LFP (140 nm), is obtained with 6.0 wt% carbon content. The electrochemical properties are evaluated at room temperature by cyclic voltammetry and charge-discharge performance analysis using porous carbon current collector with a lithium metal anode and gel polymer electrolyte that is prepared by the phase inversion method. C-LFP exhibits a high discharge capacity of 147.3 mAh g−1 (corresponding to 87% of the theoretical capacity) at 0.5 C-rate and 139.8 mAh g−1 at 1 C-rate. Good rate capability and stable cycle performance were realized for flexible lithium polymer cells employing the biomass derived-carbon coated LiFePO4.

A joint experimental and theoretical study on the effect of manganese doping on the structural, electrochemical and physical properties of lithium iron phosphate

Mn doped LiFe1−xMnxPO4 (x = 0, 0.01, 0.03, 0.05, 0.07) cathode materials are synthesized by a carbothermal reduction method. The structure, morphology and electrochemical performance of the samples are characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), Raman, and charging–discharging tests. It is found that an appropriate amount of Mn doping did not affect the olivine structure and morphology of LiFePO4, but greatly improves its electrochemical performance. Especially, the LiFe0.97Mn0.03PO4 sample exhibits the best electrochemical performance, which shows the maximum discharge capacity of 148.2 mA h g−1 at 0.1 C and a capacity retention ratio of 98% after 60 cycles at various rates. Based on first-principles density functional theory (DFT), the lithium ion migration channels, energy band structures, densities of states, and charge density diffusion of LiFePO4 and LiFe15/16Mn1/16PO4 are calculated to further investigate the influence of Mn doping on the LiFePO4 lattice. The results prove that the higher lithium ion conduction and electronic conductivity of LiFe15/16Mn1/16PO4 are attributed to Mn doping.

Physical and Electrochemical Properties of Lithium Iron Phosphate Synthesized by Gel-Solid State Reduction Method

A lithium iron phosphate composite LiFePO4/C as cathode material for lithium ion battery was synthesized by sol-gel and high temperature solid state reduction method. The crystalline structure, morphology of particles and electrochemical performances of the sample were investigated by X-ray diffraction, scanning electron microscopy and charge-discharge test. Crystal structure and electrochemical performances of the composite relates to the heat treatment temperature. The composite synthesized under 700°C is simple pure olive-type phase structure with relative uniformly distribution of particle size. Also high charge-discharge capacity and efficiency, good cycle ability and high rate capability were observed in electrochemical tests for the composite. However, the capacity loss under high temperature, which may be the main content of further study.

Continuous synthesis of lithium iron phosphate nanoparticles in supercritical water: Effect of process parameters

This study investigates the effect of various process parameters during continuous synthesis in supercritical water on the physicochemical and electrochemical properties of lithium iron phosphate (LiFePO4) for use in large-scale lithium 2nd battery applications. The process parameters include reaction temperature (300–400°C), precursor solution concentration (0.01–0.18M), precursor solution flow rate (1.5–3.0g/min), water flow rate (9.0–36.0g/min), and residence time (9–72s). Under subcritical water conditions, mixed Fe3(PO4)2⋅8H2O, Fe2O3, and Fe3O4 particles formed; in contrast, under supercritical fluid conditions, well-crystallized LiFePO4 particles with some Fe3+ impurities (i.e., Fe2O3 and Fe3O4) were obtained. In supercritical water, an increase in the precursor concentration leads to an increase in the Fe3+ impurity content. At a high water flow rate, a significant decrease in crystallinity and the formation of Fe3(PO4)2⋅8H2O and Li6P6O18⋅9H2O phases rather than LiFePO4 were observed. Highly crystalline LiFePO4 with good discharge capacity was obtained with high temperature, low precursor concentration, and low flow rate conditions. Depending on the synthetic conditions, bare LiFePO4 particles exhibit discharge capacities of 55–85mAh/g at 0.1 C-rate after 30 cycles. After carbon coating, a marginal capacity decay from 141 to 135mAh/g was observed during the 30 charge–discharge cycles.

Interactions between organic additives and active powders in water-based lithium iron phosphate electrode slurries

The interactions of organic additives with active powders are investigated and are found to have great influence on the determination of the mixing process for preparing electrode slurries with good dispersion and electrochemical properties of lithium iron phosphate (LiFePO4) electrodes. Based on the analyses of zeta potential, sedimentation, and rheology, it is shown that LiFePO4 prefers to interact with styrene–butadiene rubber (SBR) relative to other organic additives such as sodium carboxymethyl cellulose (SCMC), and thus shows preferential adsorption by SBR, whereas SBR has much lower efficiency than SCMC in dispersing LiFePO4. Therefore, for SCMC to interact with and disperse LiFePO4 before the interaction of LiFePO4 with SBR, it is suggested to mix SCMC with LiFePO4 prior to the addition of SBR during the slurry preparation process. For the electrode prepared via the suggested process, i.e., the sequenced adding process in which SCMC is mixed with active powders prior to the addition of SBR, a much better electrochemical performance is obtained than that of the one prepared via the process referred as the simultaneous adding process, in which mixing of SCMC and SBR with active powders in simultaneous.

Influence of 1-D Nano Rod Structure β-MnO2 on Electrochemical Properties of Lithium Iron Phosphate

Influence of 1-D Nano Rod Structure β-MnO2 on Electrochemical Properties of Lithium Iron Phosphate

Synthesis and electrochemical properties of lithium iron phosphate

Original method for synthesis of lithium iron phosphate was developed. The method includes two stages: 1st, synthesis of iron phosphate from a mixture of ammonium dihydrophosphate and metal oxide; and 2nd, synthesis of lithium iron phosphate by thermal lithiation of the product obtained in the 1st stage, with mechanical activation of the precursor in the course of plastic deformation.

Morphological, structural and electrochemical properties of lithium iron phosphates synthesized by Spray Pyrolysis

In the field of materials for lithium ion batteries, the lithium iron phosphate LiFePO 4 has been proven for use as a positive electrode due to its good resistance to thermal degradation and overcharge, safety and low cost. The use of nanostructured materials would improve its efficiency. This work shows the results of the synthesis of nanostructured materials with functional properties for lithium batteries through aerosol techniques. The Spray Pyrolysis method allows synthesizing nanostructured particles with spherical geometry, not agglomerates, with narrow distribution of particle size and homogeneous composition in respect to a precursor solution. Experimental techniques were focused on the morphological (SEM and TEM), structural (XRD and HRTEM-SAED), chemical (EDS) and electrochemical characterization.

Improving electrochemical properties of lithium iron phosphate by addition of vanadium

The poor conductivity, resulting from the low lithium-ion diffusion rate and low electronic conductivity in the LiFePO 4 phase, has posed a bottleneck for commercial applications. Well-crystallized LiFePO 4-based powders with vanadium addition were synthesized with solution method. The synthesized powders are coated with carbon. The powder containing the well-mixed LiFePO 4 and Li 3V 2(PO 4) 3 phases (LFVP) with narrow distributed particle size ranging between 0.5 and 2.5 μm exhibits improved electrochemical performance. The small particle size and the presence of the electronically conductive mixed phases can be the reasons why the cells containing LFVP exhibit the high discharge capacity of about 100 mAh g −1 at 10 C, whereas the samples with single phase, such as LiFePO 4 and Li 3V 2(PO 4) 3, have the discharge capacity less than 80 Ah g −1 at the same rate.