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A kind of ferrous phosphate and preparation method thereof, lithium iron phosphate positive electrode active material and preparation method thereof

A technology of lithium iron phosphate and ferrous phosphate, which is applied in the field of lithium-ion batteries, can solve the problems of poor electrochemical performance and large particle size of lithium iron phosphate, and achieve the effect of improving activity

Active Publication Date: 2018-12-21
BYD CO LTD
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  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0008] The object of the present invention is to provide a kind of ferrous phosphate and its preparation method, lithium iron phosphate positive electrode active Materials and their preparation methods

Method used

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  • A kind of ferrous phosphate and preparation method thereof, lithium iron phosphate positive electrode active material and preparation method thereof
  • A kind of ferrous phosphate and preparation method thereof, lithium iron phosphate positive electrode active material and preparation method thereof
  • A kind of ferrous phosphate and preparation method thereof, lithium iron phosphate positive electrode active material and preparation method thereof

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[0034] According to the preparation method provided by the present invention, preferably, the mass concentration of the phosphoric acid is 10%-50%. The mass concentration of phosphoric acid will affect the amount of phosphoric acid molecules distributed around the unit metal iron. The amount of phosphoric acid molecules will accelerate the reaction between metal iron and phosphoric acid and shorten the reaction cycle. However, if the reaction is too fast, it will affect the morphology and shape of the synthesized ferrous phosphate. granularity. The invention controls the mass concentration of the phosphoric acid to be 10%-50%, and can obtain the ferrous phosphate with uniform particle size while ensuring the reaction speed.

[0035]According to the preparation method provided by the present invention, preferably, the metallic iron is at least one of iron powder, iron block and iron rod. Further preferably, the metallic iron is iron powder. The average particle size of the ir...

Embodiment 1

[0049] 1. Preparation of ferrous phosphate

[0050] Weigh 30.0mol metallic iron powder (purity 99.9wt%, average particle size 1um) and 35.3mol phosphoric acid (mass concentration 85%). Dilute phosphoric acid into a 30% phosphoric acid solution. Then metal Fe powder is added into the phosphoric acid solution and transferred to the autoclave together, nitrogen is introduced into the autoclave, and the change of the oxygen content in the autoclave is monitored at the same time, when the oxygen content is reduced to below 100ppm, the pressure is 1Mpa, airtight reactor. Raise the temperature to 50°C. After 5 hours, after the iron powder and phosphoric acid have completely reacted, lower the temperature in the kettle to room temperature 25°C to obtain ferrous phosphate A1 slurry with a pH of 3.5.

[0051] Dry the slurry of ferrous phosphate A1, and then use a scanning electron microscope to test its SEM image, the results are shown in figure 2 . The scanning electron microscope...

Embodiment 2

[0058] 1. Preparation of ferrous phosphate

[0059] Weigh 30.0mol metallic iron powder (purity 99.9wt%, average particle size 100um) and 35.3mol phosphoric acid (mass concentration 85%). Dilute phosphoric acid to a 50% phosphoric acid solution. Then metal Fe powder is added into the phosphoric acid solution and transferred to the autoclave together, nitrogen is introduced into the autoclave, and the change of the oxygen content in the autoclave is monitored at the same time, when the oxygen content is reduced to below 100ppm, the pressure is 2Mpa, airtight reactor. Raise the temperature to 40°C. After 5 hours, after the iron powder and phosphoric acid have completely reacted, lower the temperature in the kettle to room temperature 25°C to obtain ferrous phosphate A2 slurry with a pH of 3.2.

[0060] Dry the slurry of ferrous phosphate A2, and then test its SEM image with a scanning electron microscope, the results are shown in image 3 . The scanning electron microscope (S...

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Abstract

The invention provides ferrous phosphate, a preparation method therefor, a lithium iron phosphate positive electrode active material and a preparation method therefor. The ferrous phosphate comprises flake-like particles and small particles distributed on surfaces of the flake-like particles; and particle size distribution of the flake-like particles is 5-10 micrometers, and particle size distribution of the small particles is 0.1-2 micrometers. The ferrous phosphate prepared in the invention serves as a lithium ion battery positive electrode material and is high in compacted density, the charge capacity and discharge capacity of the lithium ion battery of the invention are not much different from those of an existing lithium ion battery, but the capacity maintenance rate of the lithium ion battery obtained in the invention is far greater than that of the existing lithium ion battery after 500 charging and discharging cycles. From the result, by the method, lithium iron phosphate with small particle size and good electrochemical performance can be obtained, and an industrial application prospect is quite optimistic.

Description

technical field [0001] The invention belongs to the field of lithium ion batteries, and in particular relates to ferrous phosphate and a preparation method thereof, lithium iron phosphate positive electrode active material and a preparation method thereof. Background technique [0002] In recent years, lithium-ion batteries, as chemical power sources with high specific capacity, have been widely used in mobile communications, notebook computers, video cameras, cameras, portable instruments and other fields. The first choice for alternative energy sources. [0003] Lithium iron phosphate (LiFePO 4 ) due to its high specific capacity (170mAh·g -1 ), low raw material prices, environmental friendliness, high safety, and good cycle performance have become the most potential positive electrode active materials for lithium-ion power batteries. Preliminary studies have shown that LiFePO 4 Concentrated LiCoO 2 , LiNiO 2 , LiMnO 4 The respective advantages of other materials: n...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C01B25/26C01B25/45H01M4/58
CPCY02E60/10
Inventor 李阳曹文玉肖峰张文伟连水平
Owner BYD CO LTD
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