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

A lithium-ion battery and lithium iron phosphate technology, applied in the field of phosphate, can solve the problems of high preparation cost, large equipment investment, and poor electrochemical performance, and achieve low preparation cost, small equipment investment, and improved electronic conductivity.

Inactive Publication Date: 2009-09-16
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 iron phosphate of lithium ion battery anode material
  • Hydro-thermal synthetic preparation method for lithium iron phosphate of lithium ion battery anode material

Examples

Experimental program
Comparison scheme
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; 461.2g of 85% phosphoric acid containing 4mol of pure phosphoric acid 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 in 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 syste...

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 hydrothermal synthesis preparation method of lithium iron phosphate cathode material of lithium ion battery of the present invention, it relates to the phosphate containing two kinds of metals, and the step is to dissolve lithium source and phosphorus source in water or mix with water, add in autoclave, use After purging the air in the dead volume of the autoclave with inert gas, seal the autoclave, heat it from room temperature to 40-50 ° C under stirring, open the feed valve and exhaust valve, and then add the refined ferrous salt solution, and then Seal the autoclave and react at 140-170°C for 200-480 minutes. At this time, the autogenous pressure corresponding to the system is 0.36-0.85MPa, and the ratio of the added substances is: Li:Fe:P molar ratio is 3.0-3.15:1: 1.0 to 1.15. When the reaction starts, the reactant concentration is 0.2 to 1.0 mol / L in terms of ferrous ion concentration, and then the product is filtered, washed, dried and carbon coated to obtain the lithium iron phosphate product. The invention has the advantages of simple process, good batch stability and good electrochemical performance, the purity can reach more than 99%, the particle diameter D50 is 1.5-2 μm, and the distribution is uniform.

Description

technical field [0001] The technical solution of the invention relates to a phosphate containing two metals, specifically a hydrothermal synthesis preparation method of lithium iron phosphate, a cathode material of a lithium ion battery. Background technique: [0002] Most commercial lithium-ion batteries currently use LiCoO 2 for the positive electrode material. Due to the LiCoO under overcharge condition 2 It will release active oxygen and cause the organic electrolyte to catch fire, the battery will explode, and other safety issues and higher prices. Therefore, people have been experimenting to develop ideal electrode active materials with excellent performance and easy-to-obtain raw materials. In 1997, Goodenough et al synthesized LiFePO with olivine type 4 and use it as a 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 extraction and insertion of lith...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C01B25/45H01M4/58
CPCY02E60/10
Inventor 欧秀芹梁广川梁金生徐圣钊王丽
Owner HEBEI UNIV OF TECH
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