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Lithium ion battery and positive electrode piece thereof

A technology for lithium-ion batteries and positive pole pieces, applied to battery electrodes, non-aqueous electrolyte battery electrodes, secondary batteries, etc., can solve problems such as large interface resistance, low adhesion, and active material falling off, and prolong cycle life , reduce interface resistance, improve the effect of adhesion

Inactive Publication Date: 2017-07-11
NINGDE AMPEREX TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Since the active material on the positive electrode sheet itself is relatively hard and brittle, the bonding force between it and the aluminum foil current collector is low, and the interface resistance is large, which is not conducive to the dynamic performance of the lithium-ion battery. During the discharge and long cycle process, it is easy to cause the active material to fall off, leading to the failure of the lithium-ion battery, and even the danger of short circuit and fire, which is difficult to meet the needs of long cycle life.
In order to improve the binding force of the active material on the positive electrode sheet, it is necessary to increase the amount of binder, but this will not only reduce the energy density of the lithium-ion battery, but also greatly deteriorate the charge and discharge rate performance of the battery. The help of improving cycle life is not obvious

Method used

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  • Lithium ion battery and positive electrode piece thereof
  • Lithium ion battery and positive electrode piece thereof
  • Lithium ion battery and positive electrode piece thereof

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0029] Mix 30 parts of conductive agent, 70 parts of copolymerized Ac-PVDF (m=0.995, n=0.005) and NMP, stir evenly, and coat on both sides of aluminum foil with a controlled thickness of 1-3 μm, which is the primer layer D1.

[0030] Mix the positive active material NCM (nickel-cobalt lithium manganate ternary material), homopolymerized PVDF, and a conductive agent, and stir at a high speed to obtain a uniformly dispersed mixture containing the positive active material; in the mixture, the solid component contains 95wt% of NCM, 2wt% conductive agent and 3wt% PVDF. Using NMP (N-methylpyrrolidone) as a solvent, the above mixture was made into positive electrode active material slurry, and the solid content in the slurry was 70 wt%. The slurry was evenly coated on both sides of the substrate with the primer layer as above, dried and compacted by a roller press to obtain a positive electrode sheet, which was designated as Z1.

Embodiment 2

[0032] Mix 30 parts of conductive agent, 70 parts of copolymerized Ac-PVDF (m=0.99, n=0.01) and NMP, stir evenly, and coat on both sides of the aluminum foil with a thickness of 1-3 μm, which is the undercoat layer D2.

[0033] Mix positive active material NCM, homopolymerized PVDF, and conductive agent, and stir at high speed to obtain a uniformly dispersed mixture containing positive active material; in the mixture, the solid component contains 95wt% of NCM, 2wt% of conductive agent and 3wt% of PVDF . Using NMP (N-methylpyrrolidone) as a solvent, the above mixture was made into positive electrode active material slurry, and the solid content in the slurry was 70 wt%. The slurry was evenly coated on both sides of the substrate with the primer layer as above, dried and compacted by a roller press to obtain a positive electrode sheet, which was designated as Z2.

Embodiment 3

[0035] Mix 30 parts of conductive agent, 70 parts of copolymerized Ac-PVDF (m=0.97, n=0.03) and NMP, stir evenly, and coat on both sides of the aluminum foil with a controlled thickness of 1-3 μm, which is the primer layer D3.

[0036]Mix positive active material NCM, homopolymerized PVDF, and conductive agent, and stir at high speed to obtain a uniformly dispersed mixture containing positive active material; in the mixture, the solid component contains 95wt% of NCM, 2wt% of conductive agent and 3wt% of PVDF . Using NMP (N-methylpyrrolidone) as a solvent, the above mixture was made into positive electrode active material slurry, and the solid content in the slurry was 70 wt%. The slurry was evenly coated on both sides of the substrate with the undercoat layer above, dried and compacted by a roller press to obtain a positive electrode sheet, which was designated as Z3.

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Abstract

The invention discloses a lithium ion battery and a positive electrode piece thereof. The positive electrode piece comprises a positive electrode current collector, a priming coat coated on the positive electrode current collector and a positive electrode diaphragm coated on the priming coat, the positive electrode current collector is aluminum foil, and the positive electrode diaphragm contains a positive electrode active material and a PVDF homopolymer binder; and the priming coat comprises a conductive agent and acrylic acid modified polyvinylidene fluoride copolymer (Ac-PVDF) used as a binder. The priming coat is introduced to the positive pole electrode piece of the lithium ion battery, the priming coat mainly contains the acrylic acid modified polyvinylidene fluoride copolymer and the conductive agent, the Ac-PVDF can significantly increase the adhesion between the positive electrode diaphragm and the positive current collector, and the conductive agent can reduce the interface resistance, so the charge and discharge performance of the battery is improved, and the cycle life of the battery is prolonged.

Description

technical field [0001] The invention belongs to the technical field of lithium ion batteries, and more specifically, the invention relates to a lithium ion battery and its positive electrode sheet. Background technique [0002] In the existing energy system, non-renewable resources such as coal and oil are scarce, and the use of them has also brought great environmental pollution. Therefore, it is necessary to develop new energy sources to solve energy crisis and environmental problems. Lithium-ion batteries have the advantages of small size, light weight, long cycle life, etc., and can realize the storage and release of electricity, which is an ideal new energy carrier. In recent years, in order to reduce oil consumption and reduce environmental pollution, the development of power lithium-ion batteries suitable for electric vehicles (EVs) has become the development trend of the global automotive industry. [0003] Power lithium-ion batteries have high performance requireme...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H01M4/13H01M4/66H01M4/36H01M4/62H01M10/0525
CPCH01M4/13H01M4/36H01M4/623H01M4/624H01M4/661H01M10/0525Y02E60/10
Inventor 钟泽刘会会王星会孙成栋魏增斌
Owner NINGDE AMPEREX TECH
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