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Collosol-coating preparation method of lithium iron phosphate being the positive electrode material of lithium ion battery

A lithium iron phosphate, lithium ion battery technology, applied in electrode manufacturing, battery electrodes, chemical instruments and methods, etc., can solve the problem of low electronic conductivity and ionic conductivity, high requirements for precursor manufacturing equipment, and high rate charge and discharge Poor performance and other problems, to achieve stable electrochemical performance, avoid uneven mixing problems, and stable product performance

Inactive Publication Date: 2009-11-11
HEBEI LITAO BATTERY MATERIAL
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  • Abstract
  • Description
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  • Application Information

AI Technical Summary

Problems solved by technology

[0003] Lithium iron phosphate has two obvious disadvantages, which seriously limit its practical application: (1) low electronic conductivity and ionic conductivity, resulting in poor high-rate charge and discharge performance and low actual specific capacity
(2) The bulk density is low, resulting in low volume specific capacity
However, just like the liquid-phase synthesis of other materials, this method requires high precursor manufacturing equipment, complex process control, and is not easy to mass produce
Patent CN 101154722 proposes a method of making precursor powder by gelatinization of modified starch and then sintering to obtain the finished product of lithium iron phosphate. However, it is difficult to realize large-scale industrial production after the proposed process of stirring and evaporating after gelatinization

Method used

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Examples

Experimental program
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Effect test

Embodiment 1

[0033] Lithium-ion battery cathode material lithium iron phosphate sol coating preparation method: first disperse 3Gg of natural plant starch in 97g of distilled water, then mix iron acetate, lithium hydroxide, and ammonium dihydrogen phosphate in accordance with the stoichiometric ratio 20g into the starch suspension Cloudy liquid. High-speed shear liquid phase dispersion was used for 0.5 hours. Then, it is pulverized by a colloid mill, so that the particle size of the solid powder is further ground to below 1 micron. Put the dispersed liquid into the reaction kettle, slowly raise the temperature to 85°C under stirring, and keep the temperature constant for 5 hours to form a high-viscosity gel-like solution in which the solid powder is uniformly dispersed. Pass the gel suspension into the casting machine and coat it into a slurry layer with a thickness of 1mm. The slurry layer is dried in the drying channel at 80°C for about 1 hour, and the solid powder is densely settled to...

Embodiment 2

[0036]Lithium-ion battery cathode material lithium iron phosphate sol coating preparation method: first disperse 10g of soluble starch in 90g of distilled water, then mix 100g of ferric nitrate, lithium carbonate, and ammonium hydrogen phosphate in accordance with the stoichiometric ratio into the prepared liquid . Use a high-speed shear disperser to disperse for 1 hour. Then, it is pulverized by a colloid mill, so that the particle size of the solid powder is further ground to below 1 micron. Put the dispersed liquid into the reaction kettle, slowly raise the temperature to 100°C under stirring, and keep the temperature constant for 1 hour to form a high-viscosity gel-like solution in which the solid powder is uniformly dispersed. Pass the gel suspension into the casting machine and coat it into a slurry layer with a thickness of 1mm. The slurry layer is dried in the drying channel at 110°C for about 0.5 hours, and the solid powder is densely settled to form a dense xerogel....

Embodiment 3

[0039] Lithium-ion battery cathode material lithium iron phosphate sol coating preparation method: first disperse 6.5g of natural plant starch in 93.5g of distilled water, then mix 50g of ferric oxalate, lithium nitrate, and triammonium phosphate that meet the stoichiometric ratio into the prepared in the liquid. Use a high-speed shear disperser to disperse for 0.75 hours. Then, it is pulverized by a colloid mill, so that the particle size of the solid powder is further ground to below 1 micron. Put the dispersed liquid into the reaction kettle, slowly raise the temperature to 90°C under stirring, and keep the temperature constant for 3 hours to form a high-viscosity gel-like solution in which the solid powder is uniformly dispersed. Pass the gel suspension into the casting machine and coat it into a slurry layer with a thickness of 2mm. The slurry layer is dried in the drying channel at 105°C for about 0.75 hours, and the solid powder is densely settled to form a dense xerog...

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Abstract

The invention relates to a collosol-coating preparation method of lithium iron phosphate being the positive electrode material of a lithium ion battery, pertaining to the technical field of lithium ion battery. The technique of the invention comprises the following steps of: 1. preparing starch suspension: starch is dispersed in distilled water and then a ferric source, a lithium source compound and a phosphorus source compound are mixed into the starch suspension; 2. compound dispersion: firstly, shear liquid-phase dispersion is conducted and colloid grinding is then conducted; 3. hydrolysis: after dispersion, the suspension is put into a reaction kettle at a temperature slowly increasing to 85-100 DEG C and constant temperature is kept for 1-5h; 4. drying: a gelatinous solution is added into a casting machine and a base body is coated with a pulp layer with the thickness of 1-5mm by a drawing knife and the pulp layer is dried at the temperature of 80-110 DEG C to form compact dried gel; and 5. heat treatment: the dried gel is arranged in a gas sintering furnace and heat treatment is conducted at high temperature of 600-800 DEG C under the protection of inert gas to obtain a product. The preparation method has the advantages of high tap density of lithium iron phosphate, high discharge capacity, simple technique, stable product performance, high yield, applicability to industrialization and the like.

Description

technical field [0001] The invention belongs to the technical field of lithium ion batteries, and in particular relates to a preparation method for coating lithium iron phosphate sol, a cathode material of lithium ion batteries. Background technique [0002] Currently, LiFePO 4 It has the advantages of high theoretical capacity and high working voltage, small self-discharge, no memory effect, etc., especially LiFePO 4 There is only about 6% volume change during charge and discharge, and the anion group PO 4 3- Very stable, resulting in an unusually high cycle life (about 2000 cycles) and extremely stable safety performance of the material. [0003] Lithium iron phosphate has two obvious disadvantages, which seriously limit its practical application: (1) The electronic conductivity and ionic conductivity are low, resulting in poor high-rate charge and discharge performance and low actual specific capacity. (2) The bulk density is low, resulting in low volume specific capa...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H01M4/04H01M4/58C01B25/45
CPCY02E60/12Y02E60/10
Inventor 王淑芹
Owner HEBEI LITAO BATTERY MATERIAL
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