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Positive pole piece and lithium ion battery comprising positive pole piece

A technology of positive electrode sheet and positive current collector, which is applied in the direction of positive electrode, battery electrode, secondary battery, etc., can solve the problems of poor safety performance, poor battery safety performance, safety hazards, etc., and achieve the improvement of DCIR growth and change rate. , the effect of improving cycle performance

Active Publication Date: 2020-12-11
浙江冠宇电池有限公司
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

In recent years, the development of volume energy density and mass energy density of digital lithium-ion batteries has almost reached the limit of materials. Due to the poor safety performance of high-voltage lithium cobaltate (≥4.4V) and high-nickel materials, the safety performance of the corresponding batteries Performance deteriorates, and lithium-ion batteries use flammable organic solvents as electrolyte solvents, which poses safety hazards

Method used

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  • Positive pole piece and lithium ion battery comprising positive pole piece
  • Positive pole piece and lithium ion battery comprising positive pole piece
  • Positive pole piece and lithium ion battery comprising positive pole piece

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0061] (1) The positive electrode active material lithium iron phosphate (D 50 <3μm), the conductive agent SP and the binder 5130 glue are mixed at a weight ratio of 86%:4%:10%, and the mixture is dispersed in NMP, and the safety layer slurry is obtained after double planetary stirring. The safety layer slurry was coated on the front and back sides of an aluminum foil current collector with a thickness of 12 μm, dried after coating, and the thickness of the coating layer on one side was 5 μm, to obtain a positive electrode sheet containing a safety layer.

[0062] (2) PVDF and carbon nanotubes are mixed at a weight ratio of 40%:60%, and the mixture is dispersed in NMP, and the conductive layer slurry is obtained after stirring by double planets. The conductive layer slurry is coated on the surface of the positive electrode sheet containing the safety layer, and dried after coating. The thickness of the coating layer on one side is 2 μm, and the positive electrode sheet contain...

Embodiment 2

[0078] The preparation method of embodiment 2 is the same as embodiment 1, except that step (2):

[0079] (2) PVDF and SP are mixed in a weight ratio of 35%:65%, the mixture is dispersed in NMP, and the conductive layer slurry is obtained after double planetary stirring. The conductive layer slurry was coated on the surface of the positive electrode sheet containing the safety layer, dried after coating, and the coating thickness on one side was 2 μm, so as to obtain the positive electrode sheet containing the conductive layer and the safety layer.

Embodiment 3-8

[0094] The preparation method of Examples 3-8 is the same as that of Example 1, except that the selection and additives of the first conductive agent, the first binder, and the first positive electrode active material in step (1) are different, as shown in Table 2.1. Show.

[0095] Table 2.1 The composition of the positive electrode sheet of Example 1, 3-8 and Comparative Example 2-3

[0096]

[0097] Table 2.2 Lithium-ion battery performance test results of Examples 1, 3-8 and Comparative Examples 2-3

[0098]

[0099] As can be seen from Table 2.2, the types of positive active materials in the safety layer in the positive electrode sheet with the three-layer structure of the present invention are different, and there is a large difference in the safety performance of lithium-ion batteries. Through comparative studies, it is found that safe The positive electrode active material in the layer is in the charging voltage range of 2.5V to 4.3V and the charging rate of 0.2C...

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Abstract

The invention provides a lithium ion battery positive pole piece and a preparation method thereof. The positive pole piece comprises a positive current collector, a safety layer, a conductive layer and an active substance layer, and the charging capacity of a first positive active substance accounts for greater than or equal to 75% of the total capacity; compared with the conventional pole piece with a two-layer coating structure, the novel multi-layer coating pole piece has higher safety and more excellent cycle performance by using the novel multi-layer coating pole piece structure design; and by using a multi-layer coating technology and utilizing the high conductivity of the conductive layer, the interface problem of the safety layer and the active substance layer in the positive polepiece, caused by poor electronic conductivity in the circulation process, can be improved, so the safety of the high-energy-density lithium ion battery is ensured, and meanwhile, the cycle performanceof the lithium ion battery and the problem of large DCIR growth change rate in the cycle process can be further improved.

Description

technical field [0001] The invention belongs to the technical field of lithium ion batteries, and in particular relates to a positive pole piece and a lithium ion battery including the positive pole piece. Background technique [0002] Power batteries and high-voltage digital batteries are currently developing rapidly, and are widely used in 3C consumer digital fields such as mobile phones, notebook computers, tablet computers, and small Bluetooth batteries and electric vehicles. Whether it is digital or power fields, the requirements for the safety performance of lithium-ion batteries are getting higher and higher. In recent years, the development of volume energy density and mass energy density of digital lithium-ion batteries has almost reached the limit of materials. Due to the poor safety performance of high-voltage lithium cobaltate (≥4.4V) and high-nickel materials, the safety performance of the corresponding batteries Performance deteriorates, and lithium-ion batter...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H01M4/131H01M4/36H01M4/48H01M10/0525H01M4/02H01M4/58H01M4/62
CPCH01M4/131H01M10/0525H01M4/366H01M4/48H01M4/58H01M4/62H01M2004/028Y02E60/10
Inventor 曾家江樊亚楠伍鹏李素丽
Owner 浙江冠宇电池有限公司