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Preparation method of lithium iron phosphate

A technology of lithium ferrous phosphate and phosphorus source, applied in chemical instruments and methods, phosphorus compounds, inorganic chemistry, etc., can solve the advantages and disadvantages of not showing the rate performance, not showing the advantages and disadvantages of high and low temperature performance of materials, not conducive to industry Chemical production and other problems, to achieve the effect of improving uniformity

Inactive Publication Date: 2012-03-21
李文宝
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  • Description
  • Claims
  • Application Information

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Problems solved by technology

In this method, the whole process is placed under nitrogen protection. This process condition is not conducive to industrial production, and the advantages and disadvantages of its rate performance are not shown in the patent.
[0005] CN101117216A discloses a method for synthesizing lithium ferrous phosphate by hydrothermal method. Lithium ferrous phosphate is prepared with ferrous sulfate, phosphoric acid and lithium hydroxide as raw materials. The high and low temperature performance of the obtained material is not shown in the patent

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  • Preparation method of lithium iron phosphate
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  • Preparation method of lithium iron phosphate

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preparation example Construction

[0016] According to the present invention, the method for preparing the lithium iron phosphate includes the following steps:

[0017] (1) The aqueous solution liquid stream containing the iron source and the phosphorus source is mixed with the aqueous solution liquid stream of the lithium source in an inert atmosphere in a co-current feeding manner, and the pH value of the obtained mixture is controlled by a pH value regulator to be 7-9, The molar ratio of Li:Fe:P in the lithium source, iron source and phosphorus source is 1.5-3:1:1.04-1.1. After the addition is completed, the temperature is raised to 150-250°C, and the reaction is carried out for 4-8 hours under stirring. And cooled to below 80°C, filtered, washed and precipitated to a sulfate content or chloride content of less than 0.5% by weight, preferably less than 0.2% by weight, to obtain a lithium iron phosphate precursor;

[0018] (2) Mix the lithium iron phosphate precursor obtained in step (1) with a soluble carbon sour...

Embodiment 1

[0038] This example is used to illustrate the preparation of lithium iron phosphate provided by the present invention.

[0039] (1) Weigh 27.93kg (100mol) of ferrous sulfate (containing 99.55% by weight of ferrous sulfate), 12.07kg (105mol) of phosphoric acid (mass percentage concentration of 85.25%), and dilute phosphoric acid to 80L with water at room temperature. Then add it to ferrous sulfate, stir to dissolve, add 25g of ascorbic acid powder to this solution, add water to 100L to obtain an acidic aqueous solution A containing iron source and phosphorus source; weigh 12.60kg monohydrate lithium hydroxide (99.98% ), dissolved in water, and diluted to 100L to obtain an alkaline aqueous solution B containing a lithium source. In addition, 20 g / L of lithium hydroxide was prepared as the pH regulator of the reaction system, and this was solution C.

[0040] (2) First, purge the reaction tank with nitrogen to remove the air in it, start stirring, and add the acidic aqueous solution ...

Embodiment 2

[0057] This example is used to illustrate the preparation of lithium iron phosphate provided by the present invention.

[0058] (1) Weigh out 55.86 kg (200 mol) of ferrous sulfate (containing 99.55% by weight of ferrous sulfate), and 23.04 kg (218 mol) of lithium dihydrogen phosphate (98.32% by mass). Lithium hydride is dissolved and diluted to 100L, then added to ferrous sulfate, stirred to dissolve, and 50g of ascorbic acid powder is added to this solution, and water is added to 120L to obtain an acidic aqueous solution A containing iron and phosphorus sources; weigh 16kg Lithium hydroxide (99.98%) is dissolved in water and diluted to 80L to obtain an alkaline aqueous solution B containing lithium salt. In addition, 20g / L of ammonia water was prepared as the pH adjuster of the reaction system, which was solution C.

[0059] (2) First, purge the reaction tank with nitrogen to remove the air, start stirring, and add the acidic aqueous solution A and the alkaline aqueous solution B...

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Abstract

The invention provides a preparation method of lithium iron phosphate, wherein the method comprises the following steps of: (1) mixing the fluid flow of an aqueous solution containing an iron source and a phosphorus source with the fluid flow of an aqueous solution containing a lithium source in a concurrent flow charging way at an inert atmosphere, raising the temperature to 150-250 DEG C after the charging is finished, reacting for 4-8h under stirring, cooling to the temperature lower than 80 DEG C, and filtering to obtain a lithium iron phosphate precursor; (2) mixing the lithium iron phosphate precursor obtained in the step (1), a soluble carbon source additive and water to obtain size with the solid content of 30-40wt%, spray-drying the size under the condition that the mass loss of a dried product is not larger than 5wt% below 800 DEG C; and (3) roasting the product obtained in the step (2). The lithium iron phosphate product obtained by using the method provided by the invention has favorable electrochemical performance.

Description

Technical field [0001] The invention relates to a method for preparing lithium iron phosphate. Background technique [0002] Since the commercial application of lithium-ion batteries in the 1990s, their application fields have evolved from small mobile power sources such as mobile communications and laptop computers to large-capacity and high-power power sources such as electric tools and electric vehicles. This is important for battery safety. Performance and electrochemical performance put forward higher requirements. Compared with the widely used cobalt series (LiCoO 2 ), manganese (Li 2 Mn 2 O 4 ) Compared with the positive electrode material, lithium iron phosphate (LiFePO) with an orthorhombic olivine structure 4 ) Is considered to be the most promising cathode material for power lithium-ion batteries. [0003] The synthesis method of lithium iron phosphate material can be divided into solid phase reaction method and wet chemical method from the reaction form. The solid-pha...

Claims

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Application Information

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IPC IPC(8): C01B25/45
Inventor 李文宝
Owner 李文宝