Preparation method for lithium iron phosphate

A technology of lithium ferrous phosphate and high-purity phosphoric acid, applied in chemical instruments and methods, phosphorus compounds, inorganic chemistry, etc., can solve the problems of low bulk density and low conductivity of lithium ferrous phosphate, and improve sphericity and bulk density , Improve bulk density, fluidity and good processability

Active Publication Date: 2011-04-13
李全东 +2
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0006] The purpose of the present invention is to overcome the shortage of low bulk density and low conductivity

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0018] Embodiment 1: A method for preparing lithium iron phosphate, including the following steps:

[0019] (1) Take 0.1 mol of high-purity phosphoric acid, slowly add 0.1 mol of refined battery-grade iron oxalate dihydrate, mix well, then add 0.06 mol of lithium hydroxide monohydrate, adjust the pH to 5.5, and grind in a colloid mill for 2 hours When the mixture is uniform, a high-density spherical ferrous phosphate and lithium iron phosphate mixed precursor are synthesized. After being dried at 65°C, placed in a reaction furnace, heated to 350°C at a rate of 5°C / h, kept for 3 hours, and then cooled to room temperature.

[0020] (2) Take out step (1) The resulting mixture is crushed, blended with lithium hydroxide, carbon source, and metal oxide, and the main component ratio is controlled according to Fe?Li?PO 4 =1?1?1, carbon source (graphite: sucrose mass ratio=1:3) accounts for 16% of the weight of the mixture, composite metal oxide (Sr: Zr mass ratio=1:1) accounts for 0.5% of ...

Embodiment 2

[0022] Embodiment 2: A method for preparing lithium iron phosphate, including the following steps:

[0023] The mass ratio of graphite to sucrose in the carbon source is 1:4, and the mass ratio of Sr metal oxide to Zr metal oxide in the composite metal oxide is 1:2, and other steps and process parameters are the same as in Example 1.

[0024] The average particle size of the lithium iron phosphate product is 6.2μm, and the tap density is 1.78g / cm 3 , The first discharge specific capacity at 0.2C rate at room temperature is 154mAh / g, the first discharge specific capacity at 1C rate is 142mAh / g, and the reversible capacity is 135mAh / g after 100 cycles at various rates.

Embodiment 3

[0025] Embodiment 3: A preparation method of lithium iron phosphate, including the following steps:

[0026] The mass ratio of the composite metal oxide is 1:2 to obtain Ni oxide and Mo oxide, and other steps and process parameters are the same as in Example 1.

[0027] The average particle size of the lithium iron phosphate product is 7.8μm, and the tap density is 1.76g / cm 3 , The first discharge specific capacity at 0.2C rate at room temperature is 156mAh / g, the first discharge specific capacity at 1C rate is 145mAh / g, and the reversible capacity is 138mAh / g after 100 cycles at various rates.

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Abstract

The invention discloses a preparation method for lithium iron phosphate. The method comprises the following steps: mixing high-purity phosphoric acid, lithium hydroxide and ferric oxalate; regulating the pH value to 5.0-6.0; drying the mixture at the temperature of 60-80 DEG C; heating the dried mixture to 300-400 DEG C at a rate of 5 DEG C/h in a reacting furnace; carrying out insulation reaction for 3 hours, and then cooling to room temperature; smashing the obtained mixture; evenly mixing the smashed mixture with lithium hydroxide, a carbon source and metallic oxides by a ball mill, and utilizing a colloid mill to pulp the blend at the temperature of 16-20 DEG C for 6-10 hours; and drying at the temperature of 60-80 DEG C, and sintering at the temperature of 600-800 DEG C for 3-6 hours in the reacting furnace in the presence of inert gas, thus preparing the lithium iron phosphate product. The preparation method is smart in concept and simple in process; and by means of the method, the stacking density and electrical conductivity of the lithium iron phosphate can be effectively improved.

Description

Technical field [0001] The invention belongs to the technical field of batteries and relates to a preparation method of lithium iron phosphate. Background technique [0002] In recent years, lithium iron phosphate, a positive electrode material for lithium-ion batteries, is mainly used in power lithium-ion batteries as a positive electrode active material. Japan's NTT exposed AMPO for the first time since 1996 4 (A is an alkali metal, M is a combination of Co and Fe) lithium battery cathode material with olivine structure, in 1997, researchers from Texas State University John. B. Goodenough and other researchers also reported on LiFePO 4 The characteristics of reversible migration in and out of lithium, the United States and Japan coincidentally published the olivine structure (LiMPO 4 ), the material has received great attention, and has caused extensive research and rapid development. Compared with the traditional lithium ion secondary battery cathode material (LiMn with spinel...

Claims

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Application Information

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IPC IPC(8): C01B25/45
Inventor 李全东肖遥王文武
Owner 李全东
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