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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 conductivity provide a method for preparing a lithium iron phosphate positive electrode active material with high conductivity and stable structure. The steps include:

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
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Embodiment 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, fully stir for 20min, 89.46g FeCl 3 ·6H 2O was dissolved in 1450ml of deionized water, and then gradually added dropwise to the above solution, fully stirred for 6 hours, filtered the solution, washed and dried repeatedly with distilled water and ethanol, and the precursor was roasted at 400°C for 4 hours under the protection of Ar atmosphere, and then cooled , Grinding to obtain gray-green powder. The material prepared above is used as the iron source, battery-grade lithium acetate is used as the lithium source, and the molar ratio of the two is 1:1, and 25% sucrose is added as the reducing agent, and absolute ethanol is used as the medium in a high-speed ball mill Ball milling for 2h. The ball-milled samples were dried in a vacuum drying oven at 80°C, and finally baked and heat-treated in a box-type atmosphere fu...

Embodiment 2

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

Embodiment 3

[0041] The same method as in Example 1 was used to prepare positive electrode active materials and simulated batteries, except that the iron source was changed to Fe(NO 3 ) 3 .9H 2 O, maintaining its molar ratio to the phosphorus source at 1:1.05.

[0042] Using the same method as in Example 1, the particle size of the lithium iron phosphate positive electrode active material can reach about 50nm, and the particle size is in the range of 30-50nm, and the particle size is uniform, the size is basically the same, and there is no agglomeration phenomenon . It can be seen from the XRD figure that the lithium iron phosphate prepared by the present invention has no impurity peaks, pure phase, characteristic peaks (311), (111), and (211) crystal plane diffraction peak intensity is relatively strong, and the half-peak widths are respectively 0.229, 0.249, 0.238, narrower, 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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