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Preparation method of high-density lithium iron phosphate cathode material

A technology of lithium iron phosphate and positive electrode materials, which is applied in the field of preparation of high-density lithium iron phosphate positive electrode materials, can solve the problems of insufficient drying of precursors, poor performance of lithium iron phosphate, and low solid content of slurry, and achieve excellent electrochemical performance. performance, promotion of uniform distribution, effect of low liquid content

Active Publication Date: 2018-09-14
江西省金锂科技股份有限公司
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Problems solved by technology

[0005] The purpose of the present invention is to provide a method for preparing a high-density lithium iron phosphate cathode material with excellent performance, which can effectively solve the problem of poor performance of the lithium iron phosphate prepared in the prior art, low solid content of the slurry and poor drying of the precursor during the preparation process. Sufficient, technical problems of high preparation cost and large pollution

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  • Preparation method of high-density lithium iron phosphate cathode material
  • Preparation method of high-density lithium iron phosphate cathode material
  • Preparation method of high-density lithium iron phosphate cathode material

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[0029] The present invention provides a method for preparing a high-density lithium iron phosphate cathode material. The method includes the following steps:

[0030] A. Mechanical activation: Add a certain amount of deionized water to the ball mill, and then add the lithium source, composite iron source, phosphorus source, carbon source and surfactant in proportion, where the molar ratio of Li:Fe:P is (1 ~1.2): (0.96~1.2): 1. The weight of the carbon source is 8-12% by weight of the theoretical production of lithium iron phosphate, and the weight of the surfactant is 8-20% by weight of the added amount of the lithium source; the composite iron source is It is obtained by mixing reducing iron powder with D50 of 1-2μm and iron orthophosphate with primary particles of 50-200nm in a molar ratio of 1:10 to 1:1 (preferably 1:5 to 1:1), high-speed ball milling 4~ 8 hours later, a mixed slurry is formed, and the solid content of the slurry is 52-68%;

[0031] B. Solid-liquid separation: ...

Embodiment 1

[0037] The primary particles are 50nm iron orthophosphate (FePO 4 ) 300.00 kg and 11.14 kg of metallic iron powder with a particle size D50 of 2um are mixed to obtain a composite iron source. 400 kg of deionized water is added to the ball mill, and then 73.52 kg of lithium carbonate, composite iron source, 20.68 kg of lithium dihydrogen phosphate, hard Fatty acid 41.47 kg, surfactant cetyl trimethyl ammonium bromide 18.84 kg were placed in a ball mill and ball milled to form a slurry. The milling time was 4 hours, and the slurry particle size was controlled at 1.5 microns to obtain a solid content of 65 % Homogeneously mixed slurry. Then the ball mill slurry is pumped into the diaphragm filter press with a diaphragm pump for pressure filtration, and the pressure filtration time is 1.5 hours to obtain a precursor with a moisture content of less than 15%; then the precursor is transported into the flash dryer for pressure filtration. Dry and mix, dry the inlet air temperature is ...

Embodiment 2

[0041] The primary particles are 100nm iron orthophosphate (FePO 4 ) 150.00 kg and 11.14 kg of metal iron powder with a particle size D50 of 1um are mixed to obtain a composite iron source. Add 250 kg of deionized water to the ball mill, and then add 44.33 kg of lithium carbonate, composite iron source, and 15.78 kg of stearic acid. 6.65 kilograms of alkyltrimethylammonium bromide were placed in a ball mill and ball milled to prepare a slurry. The milling time was 6 hours, and the slurry particle size was controlled at 1.0 micron to obtain a homogeneous mixed slurry with a solid content of 60%. Then the ball mill slurry was pumped into a diaphragm filter press with a diaphragm pump for pressure filtration. The pressure filtration time was 2.0 hours to obtain a precursor with a liquid content of 12%; then the precursor was transported into the flash dryer for pressure filtration. Dry and mix, dry the inlet air temperature is 150°C, the outlet air temperature is 70°C, after drying...

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Abstract

The invention provides a preparation method of a high-density lithium iron phosphate cathode material, comprising the main steps: mixing reducing iron powder and ferric phosphate according to a certain ratio to obtain a composite iron source; adding deionized water into a ball milling apparatus, adding a lithium source, the composite iron source, a phosphorous source, a carbon source and a surfactant, and performing ball milling to obtain a slurry; injecting the slurry into a diaphragm press filter to carry out solid-liquid separation to obtain a precursor having a solid content of about 85%;drying the precursor in a flash dryer to obtain precursor powder having a liquid content of less than 1%; sintering the precursor powder in a kiln with a protective atmosphere, cooling, and performingjet crushing to obtain lithium iron phosphate powder. The preparation method has the advantages that the method is simple, the cost is low and the finished material has good electrochemical properties.

Description

Technical field [0001] The invention belongs to the field of green energy materials, specifically the technical field of lithium batteries, and particularly relates to a method for preparing a high-density lithium iron phosphate cathode material. Background technique [0002] Lithium-ion batteries have the advantages of high specific energy, high working voltage, low self-discharge rate, long cycle life, and no pollution, and have become a hot spot for power battery development. As an important part of lithium-ion batteries, cathode materials are key factors that determine the safety, capacity and price of batteries. At present, the industrialized power lithium ion battery cathode materials are mainly lithium iron phosphate and high nickel ternary materials, of which the demand for lithium iron phosphate materials is relatively large. [0003] The high-temperature solid-phase method is used to produce lithium iron phosphate. At present, the general process route in the industry is...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C01B25/45H01M4/58H01M10/0525
CPCC01B25/45C01P2004/03C01P2004/61C01P2006/10C01P2006/11C01P2006/12C01P2006/40C01P2006/80H01M4/5825H01M10/0525H01M2004/028Y02E60/10
Inventor 谢香兰杨安臣肖水龙熊杜娟罗邵滨
Owner 江西省金锂科技股份有限公司
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