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Preparation method of lithium iron phosphate with surface being uniformly coated by carbon

A technology with uniform surface of lithium iron phosphate, applied in chemical instruments and methods, phosphorus compounds, inorganic chemistry, etc., can solve problems affecting electrochemical performance, limited conductive behavior of lithium iron phosphate, etc., to improve electrochemical performance and consistency Good, easy to operate effect

Inactive Publication Date: 2015-07-08
WOLONG ELECTRIC GRP CO LTD +2
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

In the above process, the organic carbon source and the lithium iron phosphate raw material are uniformly mixed in the form of particles. After the organic matter is carbonized at high temperature, the formed carbon and lithium iron phosphate are mainly mixed with each other in the form of particles. It is difficult to mix the particles of lithium iron phosphate A uniform carbon coating is formed on the surface to improve the electrical conductivity of lithium iron phosphate, which affects its electrochemical performance.

Method used

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  • Preparation method of lithium iron phosphate with surface being uniformly coated by carbon
  • Preparation method of lithium iron phosphate with surface being uniformly coated by carbon
  • Preparation method of lithium iron phosphate with surface being uniformly coated by carbon

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0022] The first step takes by weighing iron phosphate and lithium carbonate in the amount of 1:1 by lithium and iron molar ratio, takes by weighing sucrose by the amount of 10% of lithium iron phosphate quality;

[0023] In the second step, the mixture in the first step is placed in a high-energy ball mill tank, and 3 times the volume of ethanol is added to the above mixture, and ball milled for 5 hours;

[0024] In the third step, the mixture obtained in the second step is dried at 60° C. to obtain a precursor powder;

[0025] The fourth step is to place the precursor obtained in the third step in an atmosphere furnace. Under the protection of high-purity nitrogen, the heating rate of the entire heat treatment process is 5°C / min. First, it is raised from room temperature to 180°C and kept for 1 hour. Continue to raise the temperature to 750°C, keep it for 10 hours, and then lower it to room temperature to obtain a black substance, which is lithium iron phosphate whose partic...

Embodiment 2

[0027] The first step is to weigh iron phosphate and lithium carbonate in the amount of 1:1 by lithium and iron molar ratio, and take glucose in the amount of 10% of the lithium iron phosphate quality;

[0028] In the second step, place the mixture in the first step in a high-energy ball mill tank, add acetone of 3 times the volume of the above mixture, and ball mill for 5 hours;

[0029] In the third step, the mixture obtained in the second step is dried at 60° C. to obtain a precursor powder;

[0030] The fourth step is to place the precursor obtained in the third step in an atmosphere furnace. Under the protection of high-purity nitrogen, the heating rate of the entire heat treatment process is 5°C / min. First, it is raised from room temperature to 180°C and kept for 1 hour. Continue to raise the temperature to 750°C, keep it for 10 hours, and then lower it to room temperature to obtain a black substance, which is lithium iron phosphate whose particle surface is evenly coate...

Embodiment 3

[0032] The first step is to weigh iron phosphate and lithium carbonate in the amount of 1:1 by lithium and iron molar ratio, and take starch in the amount of 10% of the lithium iron phosphate quality;

[0033] In the second step, the mixture in the first step is placed in a high-energy ball mill tank, and 3 times the volume of ethanol is added to the above mixture, and ball milled for 5 hours;

[0034] In the third step, the mixture obtained in the second step is dried at 60° C. to obtain a precursor powder;

[0035] The fourth step is to place the precursor obtained in the third step in an atmosphere furnace. Under the protection of high-purity nitrogen, the heating rate of the entire heat treatment process is 5°C / min. First, it is raised from room temperature to 180°C and kept for 1 hour. Continue to raise the temperature to 750°C, keep it for 10 hours, and then lower it to room temperature to obtain a black substance, which is lithium iron phosphate whose particle surface i...

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Abstract

The invention discloses a preparation method of lithium iron phosphate with the surface being uniformly coated by carbon, relating to the preparation method of the lithium iron phosphate. At present, the lithium iron phosphate has difficulty in forming uniform carbon coating layers on the surfaces of the particles, so that the improvement on the conductivity behavior of the lithium iron phosphate is limited, and the performance of the electrochemical performance is influenced. The preparation method comprises the following steps of: 1) ball-milling step: arranging organic matters, iron phosphate and lithium-source compound in a high-energy ball milling tank, adding an organic solvent and carrying out wet-process ball milling; 2) low-temperature pretreatment step: arranging the mixture in an atmosphere furnace, under the protection of non-oxidizing atmosphere, rising the temperature from the room temperature to 140-180 DEG C at a temperature-rising rate of 2-5 DEG C / minute, and maintaining the temperature for 0.5-2 hours; and 3) dewatering and polycondensation step: raising the temperature to 600-800 DEG C at a temperature-rising rate of 5-10 DEG C / minute, and roasting for 5-15 hours to form the lithium iron phosphate with the surface being uniformly coated by the carbon. According to the technical scheme, the operation is easy, the carbon coating consistency is good, and the electrochemical performance of the lithium iron phosphate can be effectively improved.

Description

technical field [0001] The invention relates to a method for preparing lithium iron phosphate. Background technique [0002] The olivine structure of lithium iron phosphate is very stable. During the charge and discharge process, lithium ions intercalate / extract from the lattice of lithium iron phosphate, resulting in a small volume change, which has high safety, high charge and discharge efficiency, long cycle life, High specific capacity, strong resistance to overcharge and overdischarge, high temperature capacity, environmental protection and low price. At present, it is widely used in the positive electrode material of lithium-ion battery, which is the power source of new energy vehicles. [0003] Lithium-ion power batteries require fast electron conduction during use, but due to the structural limitations of lithium iron phosphate itself, the electronic conductivity is low at 10 -9 ~10 -10 S / cm, which greatly limits its application in lithium-ion batteries. At prese...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H01M4/58C01B25/45
CPCY02E60/10
Inventor 黄俊杰陈苏祥马兴强陈卓新黄良爱
Owner WOLONG ELECTRIC GRP CO LTD
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