Preparation method of lithium ion phosphate used as positive electrode active material

A positive electrode active material, lithium iron phosphate technology, applied in chemical instruments and methods, battery electrodes, phosphorus compounds, etc., can solve problems such as poor crystal lattice, poor electrical conductivity, large particle size, etc., and achieve uniform particle size distribution.

Inactive Publication Date: 2011-10-05
BYD CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0006] The present invention is in order to solve the LiFePO prepared by the prior art 4 The shortcomings of large particle size, poor crystal lattice and poor con

Method used

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  • Preparation method of lithium ion phosphate used as positive electrode active material
  • Preparation method of lithium ion phosphate used as positive electrode active material
  • Preparation method of lithium ion phosphate used as positive electrode active material

Examples

Experimental program
Comparison scheme
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Example Embodiment

[0028] Example 1

[0029] (1) Preparation of positive electrode active material

[0030] 38.08g NH 4 H 2 PO 4 Dissolve in 3100ml of deionized water, stir, add 10.6ml of aniline, stir well for 20min, add 89.46g FeCl 3 ·6H 2 O was dissolved in 1450ml deionized water, and then gradually added dropwise to the above solution, fully stirred for 6h, the solution was filtered, washed and dried with distilled water and ethanol repeatedly, the precursor was roasted at 400℃ for 4h under the protection of Ar atmosphere, and cooled , Grind to obtain gray-green powder. Use the material prepared above as the iron source, battery-grade lithium acetate as the lithium source, and the molar ratio between the two is 1:1, and 25% by mass sucrose is added as the reducing agent, and anhydrous ethanol is used as the medium in the high-speed ball mill Ball mill 2h. Place the ball-milled sample in a vacuum drying oven at 80°C, and finally perform a roasting heat treatment in a box atmosphere furnace. Unde...

Example Embodiment

[0036] Example 2

[0037] 38.08g NH 4 H 2 PO 4 Dissolve in 3200ml deionized water, stir, add 15.6ml pyrrole, stir well for 20min, add 89.46g FeCl 3 ·6H 2 O was dissolved in 1650ml of deionized water, and then gradually added dropwise to the above solution, fully stirred for 6h, filtered, repeatedly washed and dried with distilled water and ethanol to prepare the precursor. The precursor was calcined at 400℃ for 4h under the protection of Ar atmosphere. Cool and grind to obtain powder. Use the material prepared above as the iron source, battery-grade lithium acetate as the lithium source, and the molar ratio between the two is 1:1, and 25% by mass sucrose is added as the reducing agent, and anhydrous ethanol is used as the medium in the high-speed ball mill Ball mill 2h. Place the ball-milled sample in a vacuum drying oven at 80°C, and finally perform a roasting heat treatment in a box atmosphere furnace. Under the protection of Ar gas, the temperature is kept at 400°C for 6h, 70...

Example Embodiment

[0040] Example 3

[0041] The positive electrode active material and the simulated battery were prepared by the same method as in Example 1, except that the iron source was changed to Fe(NO 3 ) 3 .9H 2 O, maintain its molar ratio to the phosphorus source at 1:1.05.

[0042] Using the same method as Example 1, the particle size of the lithium iron phosphate cathode active material can reach about 50nm, the particle size is in the range of 30-50, and the particle size is uniform, the size is basically the same, and there is no agglomeration. . It can be seen from the XRD pattern that the lithium iron phosphate prepared by the present invention has no impurity peaks, pure phase, characteristic peaks (311), (111), (211) crystal plane diffraction peaks are strong, and the half-value width is 0.229, respectively. 0.249, 0.238, narrower, with perfect lattice. The specific surface area (BET) is 46.8m 2 / g.

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Abstract

The invention provides a preparation method of lithium ion phosphate, which is used as a positive electrode active material. The preparation method comprises the steps that: a. a phosphorus source, an iron source and an organic monomer solution are mixed under a controlled pH value of 4 to 6, such that a phosphate precursor is prepared; b. the phosphate precursor obtained from the step a is mixed with a lithium source, and the mixture is subject to a ball milling process; c. the resulting material obtained from the step b is baked under an inert atmosphere. The organic monomer is one or more selected from aniline, thiophene or pyrrole. The prepared lithium ion phosphate positive electrode active material is nano-sized, and has well-distributed particle sizes. The lithium ion phosphate particles can be uniformly coated with carbon with a thickness of a few nanometers, such that the conductivity of the material can be improved. With the material provided by the present invention, the electrode polarization degrees of the batteries during high rate charging/discharging are reduced, the reversible capacities of the batteries are improved, and the cycle lives of the batteries are prolonged. Also, the method provided by the present invention has advantages of low cost, high yield, stable product performance, and simple and controllable processes. With the method, large-scale clean industrial production of the material can be realized.

Description

technical field [0001] The invention relates to a preparation method of lithium iron phosphate cathode active material. 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. . [0003] Lithium-ion battery cathode material is a hot and difficult point in the research of existing technologies, and LiCoO 2 , due to the scarcity of cobalt resources and environmental pollution, resulting in high battery production costs and other issues, seeking new materials is the difficulty of the current general research. Current Research Hotspot LiFePO 4 , has good electrochemical performance, very stable charging and discharging platform, stable structure during charging and discharging, and has the advantages of non-toxic, non-polluting, good safety performance, can be used in high temperature environments, and a wide ra...

Claims

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Application Information

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IPC IPC(8): H01M4/1397H01M4/58C01B25/45
CPCY02E60/122Y02E60/12Y02E60/10
Inventor 王强聂杰谢呈德
Owner BYD CO LTD
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