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Hydro-thermal synthetic preparation method for lithium ion battery anode material lithium iron phosphate

A lithium ion battery, lithium iron phosphate technology, applied in the field of phosphate, can solve the problems of poor electrochemical performance, high preparation cost, large equipment investment, etc., and achieve the effects of low preparation cost, short process and small equipment investment

Inactive Publication Date: 2008-02-13
HEBEI UNIV OF TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

This method effectively removes ferric iron in raw materials and prevents Fe 2+ Oxidation to obtain lithium iron phosphate containing less ferric iron impurities, which overcomes the disadvantages of poor electrochemical performance, high preparation cost and large equipment investment of lithium iron phosphate products

Method used

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  • Hydro-thermal synthetic preparation method for lithium ion battery anode material lithium iron phosphate

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Experimental program
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Effect test

Embodiment 1

[0027] The first step, hydrothermal synthesis reaction

[0028] 1112g or 4mol of FeSO 4 ·7H 2 O was dissolved in heated degassed and deoxygenated water, and diluted to 4L. After standing for 12 hours, filtered to remove a small amount of precipitate; Dilute to 1L in deoxygenated water; add 503.3g or 12mol of LiOH·H 2 O was dissolved in heated degassed and deoxygenated water and diluted to 3L.

[0029] Add the above-mentioned phosphoric acid solution and lithium hydroxide solution into a 10L autoclave with a sealed feeding tube and a cooling coil. After purging the air in the dead volume of the autoclave with an inert gas, seal the autoclave and heat it from room temperature to 40°C, open the feed valve and exhaust valve, then add the above-mentioned refined ferrous sulfate solution, then seal the autoclave, and react at 150°C for 300 minutes. At this time, the autogenous pressure corresponding to the system is 0.48Mpa. The proportioning ratio is: Li:Fe:P molar ratio is 3:1...

Embodiment 2

[0054] The heated degassed and deoxygenated water in Example 1 was replaced with ordinary deionized water, and other steps were the same as in Example 1. The scanning electron micrograph and the X-ray diffraction pattern spectrum of the product obtained have no change compared with Example 1. Chemical analysis showed a ferric iron content of about 0.6%. It shows that the oxidation of ferrous iron mainly occurs in the process of dissolution, mixing and reaction, rather than mainly caused by the oxidation of dissolved oxygen in water. Oxidation of ferrous iron is a rapid and spontaneous process as the pH increases during dissolution or mixing.

[0055] The test data results of the product of this embodiment are shown in Table 1.

Embodiment 3

[0057] The first step, hydrothermal synthesis reaction

[0058] 795g or 4mol of FeCl 2 4H 2 O was dissolved in ordinary deionized water and diluted to 4L with water. After standing for 12 hours, filtered to remove a small amount of precipitate; in water and diluted to 1.5L; then 503.3g or 12mol of LiOH·H 2 O was dissolved in heated degassed and deoxygenated water and diluted to 2.5 L.

[0059] Add the above phosphoric acid solution and lithium hydroxide solution into the autoclave, after purging the air in the dead volume of the autoclave with an inert gas, seal the autoclave, heat it from room temperature to 50°C while stirring at a speed of 200rpm, open the feed valve and exhaust Valve, then add the above-mentioned refined ferrous chloride solution, then seal the autoclave, and react for 200 minutes at 170°C. At this time, the autogenous pressure corresponding to the system is 0.85Mpa, and the ratio of the added substances is: Li: Fe: The molar ratio of P is 3:1:1.15, an...

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Abstract

The present invention relates to a hydrothermal synthesis preparation method of a lithium iron phosphate of an anode material used by a lithium ion battery, concerning a phosphate containing two metals. The step is that a lithium source and a phosphor source are solubilized into the water or mixed with the water and then put into a high pressure kettle. After the air in the kettle is blown out by an inert gas, the high pressure kettle is sealed and heated to a temperature between 40 DEG C and 50 DEG C from a room temperature after being stirred. An inlet valve and a vent valve are opened and then a prepared divalent ferric salt liquor is added in. The high pressure kettle is sealed and the reaction time lasts from 200 minutes to 480minutes at the temperature between 140 DEG C and 170 DEG C. At the time, the inner pressure corresponding to the system is from 0.36 MPa to 0.85 MPa. The mixture rate of the added substance is Li: Fe: P and the mol ratio is 3.0-3.15: 1: 1.0-1.15. When the reaction starts, the reactant concentration is from mol / L 0.2 to 1.0mol / L, computed according to the concentration of the ferrous ion and then the resultant is filtrated, cleaned, dried and coated with the carbon. Finally the lithium iron phosphate product can be obtained. The present invention has the advantages of simple technology, good batch stability, good electrochemical performance and even distribution. The purity quotient can be more than 99 percent and the grain diameter D50 is between1.5Mu m and 2Mum.

Description

Technical field [0001] The technical solution of the present invention relates to a phosphate containing two metals, specifically a hydrothermal synthesis method for preparing lithium iron phosphate, a cathode material for lithium ion batteries. Background technique: [0002] Currently, most commercialized lithium-ion batteries are based on LiCoO 2 For the positive electrode material. Due to overcharge conditions LiCoO 2 Reactive oxygen species will be released, causing the organic electrolyte to catch fire and the battery to explode, leading to safety issues and higher prices. Therefore, people have been experimenting to develop ideal electrode active materials with excellent performance and readily available raw materials. In 1997, Goodenough et al. synthesized olivine-type LiFePO. 4 And use it as positive electrode active material. LiFePO 4 The theoretical capacity is 170mAh / g, and the discharge platform is 3.4V. Since there is no volume change during the extractio...

Claims

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Application Information

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IPC IPC(8): C01B25/45H01M4/58
CPCY02E60/12Y02E60/10
Inventor 欧秀芹梁广川梁金生徐圣钊王丽
Owner HEBEI UNIV OF TECH
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