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Preparation method of carbon source coated lithium iron phosphate

A carbon source coating lithium iron phosphate and coating lithium iron phosphate technology, applied in the direction of active material electrodes, electrical components, battery electrodes, etc., can solve the problems of poor conductivity, fast decay of high current charge and discharge capacity, etc. Good, easy to control process conditions, the effect of improving lithium ion mobility

Active Publication Date: 2016-06-22
ANHUI UNIVERSITY OF ARCHITECTURE
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, limited by its own structure, the intrinsic electronic conductivity of lithium iron phosphate is only 10 -9 cm / s, lithium ion mobility is only 10 -16 -10 -13 cm 2 / s, which leads to problems such as poor conductivity and fast decay of high-current charge and discharge capacity. These defects undoubtedly limit the application of lithium iron phosphate in the field of battery manufacturing.

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0020] Embodiment 1: the synthesis of MDI trimer

[0021] Mix 44.4g of MDI monomer (that is, 4,4'-diphenylmethane diisocyanate) with 50mL of toluene, start the stirrer, and add 2,4,6-tris(dimethylaminomethyl Base) phenol, when the molar content of isocyanate is 8% at 60°C, add polymerization inhibitor benzoyl chloride, and react at constant temperature for 30min, cool, filter, rinse with toluene to remove MDI Monomer and catalyzer promptly get MDI trimer, the mass addition of described 2,4,6-three (dimethylaminomethyl) phenol, benzoyl chloride is respectively 0.05%, 0.05% of MDI monomer, Wherein, the molar content of isocyanate in the reactant is determined by di-n-butylamine titration.

Embodiment 2

[0022] Example 2: Preparation of carbon source coated lithium iron phosphate

[0023] 1) Weigh 1.321g (NH 4 ) 2 HPO 4 , add 2 drops of dehydrated acetone to grind, then add 0.369g of Li 2 CO 3 and 1.799g of FeC 2 o 4 2H 2 O, continue to grind evenly, and then dry at 80°C for 30 minutes to obtain the medium product;

[0024] 2) Lay the intermediate product in a corundum crucible, then put it into a tube furnace, and place it in a high-purity N 2 Under a protective atmosphere, first raise the temperature to 350°C at a rate of 2°C / min, hold for 3 hours, then raise the temperature to 700°C at a rate of 5°C / min, hold for 8 hours, then close the operating system of the tube furnace, and cool to room temperature, that is Obtain carbon source coated lithium iron phosphate. With 2mol / L LiNO 3 The solution is an electrolyte. After testing, in the AC impedance test under the three-electrode system, the lithium ion mobility of the carbon source-coated lithium iron phosphate is 3...

Embodiment 3

[0025] Example 3: Preparation of carbon source coated lithium iron phosphate

[0026] 1) Weigh 1.321g (NH 4 ) 2 HPO 4 With the MDI trimer (the same below) that 0.1g embodiment 1 makes, add 2 drops after the acetone grinding of dehydration treatment, then add the Li of 0.369g 2 CO 3 and 1.799g of FeC 2 o 4 2H 2 O, continue to grind evenly, and then dry at 80°C for 30 minutes to obtain the medium product;

[0027]2) Lay the intermediate product in a corundum crucible, then put it into a tube furnace, and place it in a high-purity N 2 Under a protective atmosphere, first raise the temperature to 350°C at a rate of 2°C / min, hold for 3 hours, then raise the temperature to 700°C at a rate of 5°C / min, hold for 8 hours, then close the operating system of the tube furnace, and cool to room temperature, that is Obtain carbon source coated lithium iron phosphate. With 2mol / L LiNO 3 The solution is an electrolyte. After testing, in the AC impedance test under the three-electrode...

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PUM

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Abstract

The invention belongs to the technical field of chemical industry, in particular relates to a preparation method of carbon source coated lithium iron phosphate for a battery cathode material. The preparation method comprises the following steps of (a) weighing and mixing (NH4)2HPO4 and MDI trimer, dropwise adding one or two drops of acetone, uniformly grinding the mixture, adding Li2CO3 and FeC2O4.2H2O, continuously and uniformly grinding the mixture, and drying the mixture to obtain an intermediate product; and (b) placing the intermediate product in a tubular furnace, in a protection atmosphere, rising a temperature to 345-355 DEG C with a speed of 2-3 DEG C per minute and preserving for 2.5-3.5 hours in a first stage, and rising the temperature to 695-705 DEG C with a speed of 4-8 DEG C per minute, preserving for 7.5-8.5 hours and cooling the intermediate product in a second stage, thereby obtaining the carbon coated lithium iron phosphate. The cathode material prepared according to the method disclosed by the invention has the advantages of low cost in raw material, simplicity in process, short time and easiness in control on process condition; and moreover, the carbon source coated lithium iron phosphate cathode material prepared according to the method is endowed with excellent electrochemical performance, and particularly, the lithium-ion mobility of the cathode material in AC impedance test under a three-electrode system can reach 8.7E-12 cm<2> per second.

Description

technical field [0001] The invention belongs to the technical field of new chemical materials, and in particular relates to a method for preparing a carbon source-coated lithium iron phosphate used for battery cathode materials. Background technique [0002] With the development of society and the seriousness of environmental problems, the research on clean and renewable energy has attracted widespread attention, such as the research on rechargeable batteries. As we all know, lithium iron phosphate, a polyanionic compound, can be used as a cathode material for lithium batteries. It has good thermal stability and environmental friendliness, so it is considered to be one of the most potential cathode materials. However, limited by its own structure, the intrinsic electronic conductivity of lithium iron phosphate is only 10 -9 cm / s, lithium ion mobility is only 10 -16 -10 -13 cm 2 / s, which leads to problems such as poor conductivity and fast decay of high-current charge an...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H01M4/36H01M4/58H01M4/62H01M4/136H01M4/1397
CPCH01M4/136H01M4/1397H01M4/362H01M4/5825H01M4/625H01M2004/028Y02E60/10
Inventor 刘瑾王琪李真王台
Owner ANHUI UNIVERSITY OF ARCHITECTURE