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Preparation method for lithium ion secondary battery positive pole active substance lithium iron phosphate

A positive electrode active material, lithium iron phosphate technology, applied in battery electrodes, chemical instruments and methods, circuits, etc., can solve problems such as uneven particle size distribution of lithium iron phosphate crystals, poor cycle performance, and low specific capacity for the first discharge , to achieve significant first discharge specific capacity and cycle performance, uniform crystal particle size distribution, and improved first discharge specific capacity and cycle performance

Inactive Publication Date: 2008-07-02
BYD CO LTD
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  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0006] The object of the present invention is to provide a preparation method of lithium ferrous phosphate in order to overcome the defects of uneven particle size distribution, low initial discharge specific capacity and poor cycle performance of lithium ferrous phosphate prepared by the prior art. The obtained lithium iron phosphate crystals have uniform particle size distribution, high initial discharge specific capacity, and good cycle performance

Method used

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  • Preparation method for lithium ion secondary battery positive pole active substance lithium iron phosphate
  • Preparation method for lithium ion secondary battery positive pole active substance lithium iron phosphate
  • Preparation method for lithium ion secondary battery positive pole active substance lithium iron phosphate

Examples

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Embodiment 1

[0022] This example illustrates the preparation of the positive electrode active material lithium iron phosphate provided by the present invention.

[0023] 323.40 g CH 3 COOLi·2H 2 O and 190 grams of glucose were dissolved in 2000 grams of deionized water and 478.10 grams of median particle size D was added 50 1.8 µm, D 95 4.0 µm FePO 4 And 5 grams of dispersant polyacrylic acid, the gained mixture is put into the water bath of 80 ℃ and heated and stirred for 1 hour, then the mixed slurry obtained is spray-dried with the QPG50 type air flow spray drier (Jingjiang Dadi Machinery Manufacturing Co., Ltd.) , spray-dried at an inlet temperature of 250°C and an atomization pressure of 0.2 MPa. The product obtained by spray drying was heated up to 500° C. at a rate of 2° C. / min under an argon atmosphere in a low-temperature tube furnace, and kept at a constant temperature for 4 hours. Then continue to heat up to 700°C at a rate of 2°C / min, and keep the temperature constant for ...

Embodiment 2

[0026] This example illustrates the preparation of the positive electrode active material lithium iron phosphate provided by the present invention.

[0027] 266.3 g CH 3 COOLi, 150 g of sucrose and 418.63 g of ammonium hydrogen phosphate were dissolved in 2000 g of deionized water, and 228.24 g of median particle size D 50 2.7 µm, D 95 3.9 microns of FeO and 6 grams of molecular weight are dispersant polyvinyl alcohol of 100,000. After stirring the resulting mixture at 100 rpm for 3 hours in an infrared heating electromagnetic stirrer (Germany SCHOTT), the temperature is raised at a speed of 5°C / min. to 90°C, and continue stirring at a speed of 100 revolutions per minute while raising the temperature until dry. The product obtained by stirring and drying was heated up to 400° C. at a rate of 5° C. / min under an argon atmosphere in a low-temperature tube furnace, and kept at a constant temperature for 4 hours. Then continue to heat up to 800°C at a rate of 5°C / min, and keep t...

Embodiment 3-7

[0029] According to the method of embodiment 1 positive electrode active material lithium ferrous phosphate, difference is, lithium compound and weight thereof, phosphorus compound and weight thereof, carbon source additive and weight thereof, lithium compound and weight thereof, weight of water, iron compound and its weight and particle size, the molar ratio of Li:Fe:P, the dispersant and its weight and molecular weight, the air inlet temperature and atomization pressure of spray drying, the heating rate, temperature and constant temperature time of the first sintering, the second The heating rate, temperature and constant temperature time of the second-stage sintering are shown in Table 1 for specific differences.

[0030] Table 1

[0031]

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Abstract

The invention relates to a preparation method of lithium iron phosphate, an active substance applied in the anode of lithium-ion secondary batteries. The method comprises the step that a mixture that contains lithium compound, iron compound, phosphorus compound, carbon source additive, water and dispersant is dried and sintered; wherein, the lithium compound, the phosphorus compound and the carbon source additive are compounds that are water soluble, while the iron compound is undissolved or insoluble in water; the dispersant is water soluble and has higher boiling point than water. The lithium iron phosphate acquired by the method has even distribution of crystal particle size, high specific capacity of initial discharge and good cycling performance.

Description

technical field [0001] The present invention relates to a preparation method of a positive electrode active material of a battery, more specifically, to a preparation method of lithium iron phosphate, a positive electrode active material of a lithium ion secondary battery. Background technique [0002] As a high-energy chemical power source, lithium-ion batteries have been widely used in mobile communications, notebook computers, video cameras, cameras, portable instruments and other fields. . LiFePO 4 It is a research hotspot of positive electrode active materials for lithium-ion batteries. LiFePO 4 As a positive electrode active material for lithium-ion batteries, compared with other batteries, it has good electrochemical performance, the charging and discharging platform is very stable, and the structure is stable during charging and discharging. The advantages of use and wide range of raw material sources are currently hot spots in the battery industry's development ...

Claims

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Application Information

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IPC IPC(8): C01B25/45H01M4/58
CPCY02E60/10
Inventor 冯克光程堂利田野
Owner BYD CO LTD
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