Method for representing cohesive force between diaphragm and pole piece of lithium battery coated with polymer

A lithium battery diaphragm and polymer technology, applied in the direction of measuring devices, instruments, and mechanical devices, can solve the problems of inability to measure the size of the bonding force, poor bonding performance, and no bonding under force, and achieve detection work High efficiency, good detection repeatability, and wide application range

Inactive Publication Date: 2017-05-31
SHENZHEN SENIOR TECH MATERIAL
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The polymer-coated diaphragm is based on a porous polyolefin diaphragm, and the surface is coated with a layer of organic material, which is bonded to the substrate through a special process. Because of the characteristics of the organic compound itself, it is coated with it The high-quality separator can be bonded to the battery pole piece under high temperature and high pressure, thereby improving the hardness of the battery and protecting the battery cell. Therefore, the bond strength between the polymer coated separator and the pole piece after hot pressing It is an important index to measure the performance of the polymer coated separator. If its bonding strength is small and the bonding performance with the substrate is poor, it cannot play the role of hardening and protecting the battery, and cannot fail to meet the hardness requirements of the battery.
[0003] At present, the method used in the industry to measure the bonding strength between the polymer-coated separator and the pole piece after hot pressing is: after the pole piece and the separator are wound into a battery core, the core is hot-pressed with a hot-press shaping machine, Observe the bonding effect of the separator and the battery pole piece with the naked eye. However, due to the narrow width of the winding core, there are creases after hot pressing, and the location of the creases has no adhesion due to the uneven force, only by naked eyes. Observing the bonding effect between the diaphragm and the pole piece not only cannot measure the size of the bonding force, but also has a lot of human subjective factors in the measurement process, and there are large errors in the test results, which cannot give diaphragm manufacturers and battery manufacturers Effective guidance, therefore, there is an urgent need for a method that can quantify and characterize the adhesive force between the polymer-coated diaphragm and the pole piece after hot pressing, so as to improve the accuracy of measurement

Method used

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  • Method for representing cohesive force between diaphragm and pole piece of lithium battery coated with polymer
  • Method for representing cohesive force between diaphragm and pole piece of lithium battery coated with polymer
  • Method for representing cohesive force between diaphragm and pole piece of lithium battery coated with polymer

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0042] In this example, the adhesion between the PVDF coating film with a thickness of 9 μm and the pole piece is tested. The thickness of the base film is 8.5 μm, and a coating with a thickness of 0.5 μm is applied on one side. The specific operation steps are as follows:

[0043] (1) Take a diaphragm sample and pole piece with a size of 100mm*300mm, and overlap them together and pass through a roller press at a slow speed, and hot press to obtain a sample. The rolling speed is 2mm / s, and the hot pressing temperature is 80°C. The hot pressing pressure is 1Mpa, and the diaphragm and the pole piece that have been rolled and bonded are cut out with a sample cutting machine, and the direction of the sample cutting is perpendicular to the direction of the coated diaphragm to obtain a test sample with a width of 12mm;

[0044] (2) Take a strip sample with a length of 200mm, gently peel off the diaphragm and one end of the pole piece by hand, and then fix the two ends of the stripped...

Embodiment 2

[0048] In this example, the adhesion between the PVDF coating film with a thickness of 16 μm and the pole piece is tested, the thickness of the base film is 14.5 μm, and a coating with a thickness of 1.5 μm is applied on one side. The specific operation steps are as follows:

[0049] (1) Take a diaphragm sample and pole piece with a size of 100mm*300mm, and overlap them together and pass through a roller press at a slow speed, and hot press to obtain a sample. The rolling speed is 5mm / s, and the hot pressing temperature is 90°C. The hot pressing pressure is 1.5Mpa, and the diaphragm and the pole piece bonded by roll are cut out with a sample cutting machine, and the direction of the cutting sample is perpendicular to the direction of the coated diaphragm to obtain a test sample with a width of 15mm;

[0050] (2) Take a strip sample with a length of 200mm, gently peel off the diaphragm and one end of the pole piece by hand, and then fix the two ends of the stripped sample in the...

Embodiment 3

[0054] In this example, the bonding force between the PVDF coating film with a thickness of 25 μm and the pole piece is tested, the thickness of the base film is 22 μm, and a coating with a thickness of 3 μm is applied on one side. The specific operation steps are as follows:

[0055] (1) Take a diaphragm sample and a pole piece with a size of 100mm*300mm, and overlap them together and pass through a roller press at a slow speed to obtain a sample by hot pressing. The rolling speed is 8mm / s, and the hot pressing temperature is 90°C. The hot pressing pressure is 1.8Mpa, and the diaphragm and the pole piece bonded by rolling are cut out with a sample cutting machine, and the direction of the sample cutting is perpendicular to the direction of the coated diaphragm to obtain a test sample with a width of 15mm;

[0056] (2) Take a strip sample with a length of 200mm, gently peel off the diaphragm and one end of the pole piece by hand, and then fix the two ends of the stripped sample...

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Abstract

The invention discloses a method for representing a cohesive force between a diaphragm and a pole piece of a lithium battery coated with polymer. The method comprises the following steps: firstly, overlapping the diaphragm coated with a coating layer with the pole piece; adopting a roller press for hotly gluing the diagram with the pole piece, wherein one side coated with the coating layer is faced to the pole piece; cutting a sample for the adhered diaphragm and pole piece coated with the polymer, thereby obtaining a bar-shaped sample; using a universal tensile testing machine for stripping the bar-shaped sample and recording a force value at a stripping moment; calculating the bonding strength between the diaphragm and pole piece coated with the polymer. The method disclosed by the invention has the advantages of being simple and convenient in operation, simple in equipment, high in detecting repeatability and high in working efficiency; the bonding strength value after hot pressing between the diaphragm and the pole piece of the lithium battery coated with polymer can be accurately and conveniently obtained; the method is suitable for the detection process for the bonding strength value after hot pressing between the diaphragm and the pole piece of the lithium battery coated with polymer in different sizes; the application scope is wide.

Description

technical field [0001] The invention belongs to the technical field of material testing, and in particular relates to a method for characterizing the thermocompression bonding force between polymer-coated lithium-ion battery separators and pole pieces. Background technique [0002] With the development of the lithium-ion battery industry, the hardness requirements for lithium-ion batteries are getting higher and higher, and polymer-coated separators have also emerged as the times require. The polymer-coated diaphragm is based on a porous polyolefin diaphragm, and the surface is coated with a layer of organic material, which is bonded to the substrate through a special process. Because of the characteristics of the organic compound itself, it is coated with it The high-quality separator can be bonded to the battery pole piece under high temperature and high pressure, thereby improving the hardness of the battery and protecting the battery cell. Therefore, the bond strength be...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G01N19/04
CPCG01N19/04
Inventor 秦银银平翔许建光廖柳辉陈良
Owner SHENZHEN SENIOR TECH MATERIAL
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