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A kind of preparation method of low-stress lithium-ion battery diaphragm

A lithium-ion battery, low-stress technology, applied in the direction of secondary batteries, battery pack components, circuits, etc., can solve problems affecting battery safety performance, warping deformation, product size changes, etc., to improve safety performance and rate performance , expand the intelligent production space, and improve the effect of heat shrinkage performance

Active Publication Date: 2020-09-22
中材锂膜(宁乡)有限公司
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0003] At present, the lithium-ion battery separators that have achieved large-scale commercial production are all polyolefin separators. During the production process, the separator material needs to be physically stretched multiple times with different strengths through equipment, and the tension is the main force. As a result, the diaphragm material has accumulated a large amount of internal stress and has no place to release it. The stress of the diaphragm is mainly due to the accumulation of polyolefin polymer raw materials when they change from solid to liquid during the hot-melt process, and are continuously stretched during the production process. There is no buffer and rebound device or process, resulting in nowhere to release the tensile stress stored in the internal structure of the material
The existence of stress will make the diaphragm prone to cracking, warping, and even product size changes. If such a diaphragm with strong internal stress is applied to battery assembly, it will cause severe shrinkage and deformation of the diaphragm during the electrochemical process. , affecting the safety performance of the battery

Method used

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  • A kind of preparation method of low-stress lithium-ion battery diaphragm
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  • A kind of preparation method of low-stress lithium-ion battery diaphragm

Examples

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Comparison scheme
Effect test

Embodiment 1

[0041] A preparation method of a low-stress lithium-ion battery diaphragm is as follows:

[0042] (1) The polyolefin polymer material and paraffin oil are melted into a fluid state, and then the polyolefin polymer material and paraffin oil compound that is melted into a fluid state is cooled by a guide roller to form a film, and the cooled composite film is Longitudinal and horizontal biaxial stretching.

[0043] (2) Perform chemical stress relief treatment on the biaxially stretched diaphragm in step (1), that is, soak the diaphragm in a 10% trichlorethylene solution for 10 minutes at a temperature of 40°C.

[0044] (3) Extract the diaphragm after chemical stress relief in step (2) at room temperature with dichloromethane solvent, wherein the ratio of dichloromethane to water in the dichloromethane solvent is 1:1, and the extraction treatment time is After 10 minutes, the organic pore-forming agent in the polyolefin material is removed, and a composite pore structure is form...

Embodiment 2

[0047] A preparation method of a low-stress lithium-ion battery diaphragm is as follows:

[0048] (1) The polyolefin polymer material and paraffin oil are melted into a fluid state, and then the polyolefin polymer material and paraffin oil compound that is melted into a fluid state is cooled by a guide roller to form a film, and the cooled composite film is Longitudinal and horizontal biaxial stretching.

[0049] (2) Perform chemical stress relief treatment on the biaxially stretched diaphragm in step (1), that is, soak the diaphragm in a 10% amyl acetate solution for 15 minutes at a temperature of 50°C.

[0050] (3) Extract the diaphragm after chemical stress relief in step (2) at room temperature with dichloromethane solvent, wherein the ratio of dichloromethane to water in the dichloromethane solvent is 1:1, and the extraction treatment time is After 15 minutes, the organic pore-forming agent in the polyolefin material is removed, and a composite pore structure is formed i...

Embodiment 3

[0053] A preparation method of a low-stress lithium-ion battery diaphragm is as follows:

[0054] (1) The polyolefin polymer material and paraffin oil are melted into a fluid state, and then the polyolefin polymer material and paraffin oil compound that is melted into a fluid state is cooled by a guide roller to form a film, and the cooled composite film is Longitudinal and horizontal biaxial stretching.

[0055] (2) Perform chemical stress relief treatment on the biaxially stretched diaphragm in step (1), that is, soak the diaphragm in a 15% trichlorethylene solution for 20 minutes at a temperature of 60°C.

[0056] (3) Extract the diaphragm after chemical stress relief in step (2) at room temperature with dichloromethane solvent, wherein the ratio of dichloromethane to water in the dichloromethane solvent is 1:1, and the extraction treatment time is After 20 minutes, the organic pore-forming agent in the polyolefin material is removed, and a composite pore structure is form...

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Abstract

The invention discloses a preparation method of a low-stress lithium-ion battery diaphragm. Firstly, polyolefin polymer material and paraffin oil are thermally melted into a fluid state, and then thermally melted into a fluid polyolefin polymer material and paraffin oil compound , after being cooled by guide rollers to form a film, the cooled composite film is stretched longitudinally and transversely, and then subjected to chemical stress relief treatment-extraction treatment-thermal radiation heating process stress relief treatment. The low-stress diaphragm material prepared by the combination of chemical stress relief treatment and thermal radiation heating process stress relief treatment effectively solves the performance defect of stress concentration of commercial polyolefin diaphragms. Under the condition of high current charge and discharge resistance, the thermal shrinkage performance of the diaphragm material is improved, thereby improving the safety performance and rate performance of the lithium-ion battery.

Description

technical field [0001] The invention relates to the field of lithium-ion battery materials, in particular to a preparation method of a low-stress lithium-ion battery diaphragm. Background technique [0002] As a key material in the production of lithium-ion batteries, the separator has an important impact on the actual performance of the battery. For example, the separator has the function of electronic insulation, which can avoid short circuits inside the battery; provide channels for ion transfer to ensure the smooth progress of electrochemical reactions; Under certain conditions, the separator can block the transmission of lithium ions through closed cells to prevent safety accidents. [0003] At present, the lithium-ion battery separators that have achieved large-scale commercial production are all polyolefin separators. During the production process, the separator material needs to be physically stretched multiple times with different strengths through equipment, and th...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H01M2/14H01M10/0525H01M50/403
CPCH01M10/0525H01M50/403Y02E60/10
Inventor 高保清冷林璘舒均国
Owner 中材锂膜(宁乡)有限公司