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Cathode of lithium ion secondary battery and lithium ion secondary battery including the same

A secondary battery and lithium-ion technology, applied in secondary batteries, battery electrodes, active material electrodes, etc., to achieve superior battery performance, high battery capacity, and high reversible capacity

Active Publication Date: 2008-05-07
BYD CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0012] The purpose of the present invention is to overcome the defect that the battery capacity, negative electrode reversible capacity and capacity retention rate in the above-mentioned prior art cannot have a high level at the same time, and to provide a lithium battery with high battery capacity, negative electrode reversible capacity and capacity retention rate. Negative electrode of ion secondary battery, and lithium ion secondary battery including the same

Method used

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  • Cathode of lithium ion secondary battery and lithium ion secondary battery including the same
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Examples

Experimental program
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Effect test

Embodiment 1

[0038] Preparation of spherical natural graphite: 200 grams of flaky natural graphite (graphite powder produced in Qingdao, China) was dissolved in 20 grams of pitch tar, dried at 200 ° C, granulated by mechanical dispersion, and then roasted at a temperature of 1200 ° C for 5 hour, cooling, to obtain spherical natural graphite A, its average particle diameter recorded is 10 microns, and the BET specific surface area is 2.6 meters 2 / g, the particle circularity is 0.86. Interplanar spacing d of (002) plane measured by X-ray diffraction method 002 at 3.357 Angstroms.

[0039] The preparation of negative electrode active material: the spherical natural graphite A of above-mentioned preparation, small particle size flaky artificial graphite (commercially available commodity, brand name is KS6, and its average particle diameter is 3 microns, and BET specific surface area is 6.3 meters 2 / g, the plane spacing d of the 002 plane measured by powder X-ray diffractometry 002 3.3369 ...

Embodiment 2

[0045] Prepare spherical natural graphite according to the same method as embodiment 1, make the average particle diameter D of gained spherical natural graphite by screening 50 15 microns, BET specific surface area is 5 meters 2 / g, the particle circularity is 0.90.

[0046] The preparation of negative electrode active material: the spherical natural graphite of above-mentioned preparation, small particle size scaly artificial graphite (average particle diameter is 5 microns, BET specific surface area is 2.82 meters 2 / g, the plane spacing d of the 002 plane measured by powder X-ray diffractometry 0020.3365 angstroms), large-scale flaky artificial graphite (average particle size is 25 microns, BET specific surface area is 3 meters 2 / g, the plane spacing d of the 002 plane measured by powder X-ray diffractometry 002 0.3367 angstroms) in a weight ratio of 80:10:10 by means of ball mill mixing, thoroughly mixed and then vacuum-dried at 200° C., and the resulting mixed graphi...

Embodiment 3

[0051] Preparation of negative electrode active material: spherical natural graphite (GP802, Hitachi powder metallurgy commodity, average particle size 18 microns, specific surface 2.6 meters 2 / g, the particle circularity is 0.85, and the plane spacing d of the 002 plane measured by powder X-ray diffraction method 002 0.3359 angstroms), small particle size flaky artificial graphite (GP-895F, Hitachi powder metallurgy commodity, its average particle size is 5 microns, and the BET specific surface area is 6 meters 2 / g, the plane spacing d of the 002 plane measured by powder X-ray diffractometry 002 0.3369 angstroms), large-grained flaky artificial graphite (GP-895G, Hitachi powder metallurgy commodity, average particle size is 20 microns, BET specific surface area is 6 meters 2 / g, the plane spacing d of the 002 plane measured by powder X-ray diffractometry 002 0.3368 angstrom) in a ratio of 95:2.5:2.5 by ball milling, thoroughly mixed uniformly, and then vacuum-dried at 200...

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Abstract

The present invention relates to a cathode of a lithium-ion, which comprises a cathode collecting body and a cathode material layer that is coated on the collecting body; the cathode material layer comprises a cathode active substance and an adhesion agent, the cathode active substance comprises a spherical-shaped natural graphite and a squamiform artificial graphite, wherein, the squamiform graphite comprises a large-granularity squamiform artificial graphite and a small-granularity squamiform artificial graphite, the average granularity D50 of the large-granularity squamiform artificial graphite is 20 to 35 micron, the average granularity D50 of the small-granularity squamiform artificial graphite is 1 to 5 micron; adopting the total quantity of the mixing graphite of the spherical-shaped natural graphite, the large-granularity squamiform artificial graphite and the small-granularity squamiform artificial graphite as the standard, the content of the spherical-shaped natural graphiteis 75 percent to 98 percent, the content of the large-granularity squamiform artificial graphite is 1 percent to 20 percent, and the content of the small-granularity squamiform artificial graphite is1 percent to 20 percent. Even the density of the cathode using the cathode active substance reaches 1.8 g / cm<3>, the cathode still has higher capacity and good cycling service life.

Description

technical field [0001] The invention relates to a negative pole of a lithium ion secondary battery and a lithium ion secondary battery comprising the negative pole. Background technique [0002] In recent years, the portability and wirelessization of civilian electronic equipment are rapidly developing, so there is an urgent need to develop a small, light-weight, and high-energy-density lithium-ion secondary battery as a driving power source for the above-mentioned electronic equipment. [0003] In the prior art, various carbon materials are generally used for negative electrodes of lithium ion secondary batteries, and the carbon materials include crystalline and amorphous, especially crystalline graphite. The lithium-ion secondary battery using graphite in the negative electrode has the advantages of high battery capacity per unit weight, high density of the negative electrode, and small initial irreversible capacity of the negative electrode. [0004] Graphite is mainly d...

Claims

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Application Information

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IPC IPC(8): H01M4/02H01M4/58H01M4/62H01M10/40H01M4/587H01M10/0525
CPCY02E60/122Y02E60/10
Inventor 孙华军肖峰
Owner BYD CO LTD
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