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Lithium iron phosphate positive electrode active material, preparation method thereof, positive electrode plate and battery

A positive electrode active material, lithium iron phosphate technology, applied in the direction of electrode manufacturing, battery electrodes, secondary batteries, etc., can solve the problem that the particle size and ratio of lithium iron phosphate materials cannot meet the closest packing and cannot effectively improve the compaction density And other issues

Pending Publication Date: 2022-02-18
BYD CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0004] At present, the industry mainly increases the compaction density by increasing the roasting temperature or reducing the carbon content in the process of synthesizing lithium iron phosphate, but this will cause the particle size and ratio of the generated lithium iron phosphate material to be unable to meet the closest packing, thus Can not effectively increase the compaction density

Method used

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  • Lithium iron phosphate positive electrode active material, preparation method thereof, positive electrode plate and battery
  • Lithium iron phosphate positive electrode active material, preparation method thereof, positive electrode plate and battery

Examples

Experimental program
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Embodiment 1

[0040] A preparation method of lithium iron phosphate cathode active material, comprising:

[0041] (1) Weigh lithium source (specifically lithium carbonate) and anhydrous ferric phosphate (wherein anhydrous ferric phosphate is used as phosphorus source and iron source at the same time) according to the molar ratio of Li:Fe:P at 1:1:1, Mix them with a carbon source (specifically glucose monohydrate), add a certain proportion of ethanol, and mix the above-mentioned materials uniformly through a high-speed disperser to make the first mixed slurry with a solid content of 45%; wherein, the carbon source The amount added can ensure that the theoretical carbon content of the first mixed slurry is 1.8% after being calcined at 790°C;

[0042] Transfer the first mixed slurry to a sand mill, grind until the particle size D50 of the slurry is about 550nm, obtain the first spray material, and spray dry the first spray material to obtain the first dry material; wherein, spray drying The i...

Embodiment 2

[0063]A method for preparing a lithium iron phosphate positive electrode active material, the difference from Example 1 is that: the amount of carbon source added in the first mixed slurry makes the theoretical carbon content of the first dry material after roasting at 750°C 1.6%; the second The amount of carbon source added in the second mixed slurry makes the theoretical carbon content of the second dry material after roasting at 750°C be 1.2%; the added amount of carbon source in the third mixed slurry makes the third dried material after roasted at 750°C The theoretical carbon content is 0.9%; the first dry material, the second dry material and the dry material are mixed in a mass ratio of 20%:20%:60%. The carbon content in the lithium iron phosphate cathode active material obtained in Example 2 was 1.1%.

[0064] There are three peaks in the particle size distribution frequency curve (by volume percentage) of the lithium iron phosphate cathode active material in Example 2...

Embodiment 3

[0066] A method for preparing a lithium iron phosphate positive electrode active material, the difference from Example 1 is that: the amount of carbon source added in the first mixed slurry makes the theoretical carbon content of the first dry material after roasting at 700°C 1.4%; the second The amount of carbon source added in the second mixed slurry makes the theoretical carbon content of the second dried material at 1.0% after roasting at 700°C; the added amount of carbon source in the third mixed slurry makes the third dried material after roasted at 700°C The theoretical carbon content is 0.8%; the first dry material, the second dry material and the dry material are mixed in a mass ratio of 15%:19%:66%. The carbon content in the lithium iron phosphate cathode active material obtained in Example 3 was 0.95%.

[0067] There are three peaks in the particle size distribution frequency curve (by volume percentage) of the lithium iron phosphate cathode active material in Examp...

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Abstract

The invention provides a lithium iron phosphate positive electrode active material, which has three peaks in a particle size distribution frequency curve counted according to volume percent, and the particle size positions of the highest points of the three peaks are respectively 0.05-0.2 mu m, 0.2-1.0 mu m and 1.0-10.0 mu m; and the integral area proportions of the three peaks are respectively 15%-32%, 3%-33% and 38%-70%. The invention also provides a preparation method of the lithium iron phosphate positive electrode active material, a positive electrode plate and a battery. The lithium iron phosphate positive electrode active material with the granularity in unique three-peak distribution can realize closest packing, and the compaction density of a pole piece prepared from the lithium iron phosphate positive electrode active material can be 2.7 g / cm < 3 > or above.

Description

technical field [0001] The invention relates to the technical field of batteries, in particular to a lithium iron phosphate cathode active material, a preparation method thereof, a cathode sheet and a battery. Background technique [0002] The cathode material of a lithium-ion battery is crucial to the performance of the battery. At present, the most studied cathode material is LiCoO 2 , LiNiO 2 , LiMn 2 o 4 、LiFePO 4 (lithium iron phosphate). Among them, the lithium iron phosphate cathode material concentrates LiCoO 2 , LiNiO 2 , LiMn 2 o 4 It has the advantages of high structural stability, good safety performance, moderate working voltage, good platform characteristics, and large theoretical capacity, etc., and has gradually become a hot research topic for battery workers. [0003] However, lithium iron phosphate has a relatively obvious shortcoming, the pole piece made of it has a low compaction density (2.1-2.3g / cm 3 ), which directly leads to the low energy ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H01M4/58H01M4/04H01M4/136H01M4/62H01M10/0525C01B25/45
CPCH01M4/5825H01M4/04H01M4/625H01M4/136H01M10/0525C01B25/45Y02E60/10
Inventor 李二阳徐茶清曹文玉
Owner BYD CO LTD
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