A high tap density lifepo 4 preparation method

A technology of tap density and high-temperature calcination, applied in chemical instruments and methods, inorganic chemistry, non-metallic elements, etc., can solve the problem of difficult control of carbon layer thickness and particle size, uneven particle size of lithium iron phosphate, and reduction of lithium iron phosphate Problems such as material tap density, to achieve excellent electrochemical performance, simple process steps, and short diffusion time

Active Publication Date: 2017-01-25
WANXIANG 123 CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

In this method, carbon coating is carried out on the surface of lithium iron phosphate particles to improve its electrical conductivity. Although carbon coating can improve the high-rate performance of lithium iron phosphate to a certain extent, carbon coating will significantly reduce the vibration of lithium iron phosphate materials. Solid density (the general tap density is less than 1.0 g / cm 3 ), thus adversely affecting the volume energy density. In addition, in the process of carbon coating, the thickness and particle size of the carbon layer on the lithium iron phosphate are not easy to control, resulting in uneven particle size of the obtained lithium iron phosphate, which will also affect the Electrochemical properties of lithium

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  • A high tap density lifepo <sub>4</sub> preparation method

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Experimental program
Comparison scheme
Effect test

Embodiment 1

[0029] (1) Lithium salt, iron salt, and phosphate are weighed according to the elemental molar ratio Li:Fe:P=1:1:1, mixed evenly, dispersed in a solvent, and then ball milled under vacuum conditions. Among them, the lithium salt It is lithium carbonate, the phosphate is ammonium dihydrogen phosphate, and the solvent is acetone. The technological conditions of one ball milling are: ball milling speed 400r / h, ball milling time 3h.

[0030] (2) The material obtained after one ball milling is subjected to low-temperature pre-calcination under an inert atmosphere. The inert atmosphere is an Ar atmosphere. The inert atmosphere is an Ar atmosphere. The process conditions for low-temperature pre-calcination are: calcination temperature 350°C, calcination time 10h.

[0031] (3) Carry out secondary ball milling on the pre-calcined material, the process conditions of the secondary ball milling are: ball milling speed 300r / h, ball milling time 1.5h.

[0032] (4) The material after seconda...

Embodiment 2

[0036](1) Lithium salt, iron salt, and phosphate are weighed according to the elemental molar ratio Li:Fe:P=4:5:5, mixed evenly, dispersed in a solvent, and then ball milled under vacuum conditions. Lithium salt is formed by carbonic acid Lithium, lithium hydroxide and lithium oxalate are mixed at a mass ratio of 1:1:2, and the phosphate is one or more of ammonium dihydrogen phosphate, diammonium hydrogen phosphate, and ammonium phosphate. The solvent is ethanol, acetone, ethylene glycol, glycerin or water, and the technological conditions of one ball milling are: ball milling speed 200r / h, ball milling time 5h.

[0037] (2) The material obtained after one ball milling was subjected to low-temperature pre-calcination under an inert atmosphere, the inert atmosphere being Ar atmosphere, wherein the inert atmosphere was Ar atmosphere, and the process conditions for low-temperature pre-calcination were: calcination temperature 300°C, calcination time 15h.

[0038] (3) Carry out se...

Embodiment 3

[0043] (1) Lithium salt, iron salt, and phosphate are weighed according to the elemental molar ratio Li:Fe:P=2.0:1:1, mixed evenly, dispersed in a solvent, and then ball milled under vacuum conditions. Among them, the lithium salt It is formed by mixing lithium acetate and lithium oxalate at a mass ratio of 1:1, and phosphate is formed by mixing ammonium dihydrogen phosphate and diammonium hydrogen phosphate at a mass ratio of 2:1, and the solvent is ethanol. The process conditions of a ball mill are: ball milling The rotating speed is 300r / h, and the ball milling time is 4h.

[0044] (2) The material obtained after one ball milling was subjected to low-temperature pre-calcination under an inert atmosphere, and the inert atmosphere was Ar atmosphere, wherein the inert atmosphere was Ar atmosphere, and the process conditions for low-temperature pre-calcination were: calcination temperature 330°C, calcination time 12h.

[0045] (3) Carry out secondary ball milling on the pre-cal...

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Abstract

The invention discloses a preparation method of high-tap-density LiFePO4 and solves a problem of a low electronic conductivity of LiFePO4 in the prior art. Through optimization design of calcination temperature, calcination time and calcinations atmosphere, during the preparation method, raw materials are directly subjected to high-temperature calcination and quick cooling, wherein a proper amount of ferrous phosphide (Fe2P) is added to the LiFePO4 and the granular size of the generated LiFePO4 material is controlled in the submicron grade, so that the LiFePO4 is high in tap density and excellent in rate capability. The preparation method is simple in processes and is low in cost. The LiFePO4 is uniform in the granular size and is high in the tap density and excellent in the rate capability.

Description

technical field [0001] The invention relates to the technical field of lithium ion batteries, in particular to a high tap density LiFePO 4 method of preparation. Background technique [0002] In commercial lithium-ion battery cathode materials, since lithium iron phosphate (LiFePO 4 ) has attracted extensive attention due to its good cycle stability, safety and environmental friendliness. However, LiFePO 4 The low electronic conductivity leads to poor high-rate performance, which seriously affects its application in electric vehicles and other fields that require high current charging and discharging. [0003] At present, one of the most commonly used methods to improve the electronic conductivity of lithium iron phosphate is to coat the surface of lithium iron phosphate particles with carbon. , the carbon source is decomposed and carbonized at high temperature, and coated on the surface of the generated lithium iron phosphate. [0004] For example, the Chinese patent a...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C01B25/45
Inventor 殷月辉吕豪杰高新宝陈军
Owner WANXIANG 123 CO LTD
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