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Negative electrode sheet, preparation method thereof, and lithium ion secondary battery comprising the same

A technology of negative electrode sheet and negative electrode, which is applied in the field of negative electrode sheet and its preparation, can solve the problems of deteriorated battery electrolyte retention, battery cycle life decline, unfavorable electrolyte storage, etc., to improve long-term cycle performance and rate performance , the effect of improving cycle performance

Active Publication Date: 2022-03-18
ZHUHAI COSMX BATTERY CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, on the one hand, the compaction density of the pole piece is getting higher and higher, resulting in a continuous decrease in the porosity of the pole piece, which is not conducive to the storage of the electrolyte, resulting in insufficient electrolyte and a decrease in the cycle life of the battery; on the other hand, in order to increase the lithium The energy density of the ion secondary battery and the thickness of the diaphragm are getting thinner and thinner, which further deteriorates the battery's ability to retain the electrolyte.

Method used

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  • Negative electrode sheet, preparation method thereof, and lithium ion secondary battery comprising the same
  • Negative electrode sheet, preparation method thereof, and lithium ion secondary battery comprising the same
  • Negative electrode sheet, preparation method thereof, and lithium ion secondary battery comprising the same

Examples

Experimental program
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Effect test

Embodiment 1

[0078] Prepare gel particles:

[0079] 60.0wt% binder SBR (styrene-butadiene emulsion), 20.0wt% thickener CMC-Na (sodium carboxymethylcellulose), 20.0wt% conductive agent SP (carbon black conductive agent) and a certain amount of deionized Add water into the planetary mixing tank, stir for 8 hours at a stirring speed of 35 Hz in revolution and 1500 Hz in rotation, make it fully mixed and prepare a uniform slurry with a viscosity of 1500-8000 mPa·s. Dried the slurry under vacuum at 80°C, crushed and sieved to obtain D 50 =5μm, the specific surface area is 2 m 2 / g of gel particles.

[0080] Preparation of negative electrode slurry:

[0081] 95.5wt% graphite, 1.5wt% binder SBR (styrene-butadiene emulsion), 1.5wt% thickener CMC-Na (sodium carboxymethylcellulose), 1.0wt% conductive agent SP (carbon black conductive agent), Add 0.5 wt% of the above-mentioned gel particles and a certain amount of deionized water into the planetary stirring tank, stir for 8 hours at a stirring sp...

Embodiment 2-11

[0087] Others are the same as in Example 1, except that the addition ratio and selection of each component in the negative electrode sheet are different, as shown in Table 1.

[0088] Table 1 The addition ratio and selection of each component in the negative electrode sheet of the embodiment and the comparative example

[0089]

[0090] Table 2 shows the porosity of the negative electrode sheets of the comparative example and the embodiment, the liquid retention capacity of the electrolyte after being assembled into a battery, and the cycle life data.

[0091] Table 2 The performance data of the negative electrode sheets of the comparative examples and the examples and the assembled batteries

[0092]

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Abstract

The invention provides a negative electrode sheet, a preparation method thereof, and a lithium ion secondary battery comprising the negative electrode sheet. The negative electrode active material layer in the negative electrode sheet includes a negative electrode active material, a first conductive agent, a first binder, a second A thickener and gel particles; the gel particles have a certain swelling property and have a good adsorption effect on the electrolyte. At the same time, the conductive agent contained in the gel particles can ensure the conductive network inside the negative plate and ensure that the negative active material Ionic and electronic conductivity between the particles in the layer. The negative electrode sheet of the present invention can solve the problem of low liquid retention of the electrolyte under high compacted density of the electrode sheet, and is beneficial to improving the long-term cycle performance of the battery. The negative electrode sheet of the present invention can increase the liquid retention capacity of the negative electrode sheet for the electrolyte under high compaction density, and improve the cycle performance of the battery.

Description

technical field [0001] The invention belongs to the technical field of lithium ion secondary batteries, and in particular relates to a negative electrode sheet, a preparation method thereof and a lithium ion secondary battery including the negative electrode sheet. Background technique [0002] Lithium-ion secondary battery, as a secondary battery widely used at present, plays an increasingly important role in people's daily life. It has the advantages of high specific energy, low self-discharge, long cycle life, and no pollution to the environment. It is widely used in power fields such as electric tools and electric vehicles, as well as digital consumer fields such as mobile phones and notebook computers. [0003] With the lightening and miniaturization of electronic products and people's desire for high power conversion efficiency, the corresponding demand for energy density of lithium-ion secondary batteries is becoming stronger and stronger. However, on the one hand, t...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H01M4/133H01M4/1393H01M4/62H01M10/0525
CPCH01M4/133H01M4/1393H01M4/621H01M4/625H01M10/0525H01M2004/027Y02E60/10
Inventor 颜世银李素丽刘春洋徐延铭李俊义
Owner ZHUHAI COSMX BATTERY CO LTD
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