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Dry uniaxial stretching process of lithium-ion battery separator, lithium-ion battery separator and lithium-ion battery

A lithium-ion battery, uniaxial stretching technology, applied in the field of lithium-ion battery separators and lithium-ion batteries, to achieve the effects of uniform pore size distribution, increased strength, and a wide range of applications

Active Publication Date: 2019-12-24
SHENZHEN SENIOR TECH MATERIAL
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0004] The preparation process of the traditional dry uniaxially stretched lithium battery separator is extrusion→casting→annealing→stretching. The tensile strength of the obtained uniaxially stretched separator is between 100MPa and 160MPa, and the puncture strength varies with thickness. By selecting raw materials with high molecular weight and low melt index, the manufacturer can make the tensile strength of the uniaxially stretched diaphragm reach 170MPa~180MPa. However, due to the safety performance of lithium-ion batteries, the strength of the diaphragm still needs to be continuously improved. There is a need for a process that can further improve the strength of dry-process uniaxially stretched lithium-ion battery separators

Method used

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  • Dry uniaxial stretching process of lithium-ion battery separator, lithium-ion battery separator and lithium-ion battery

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preparation example Construction

[0052] The preparation process of the traditional dry uniaxially stretched lithium battery separator is extrusion→casting→annealing→stretching. The tensile strength of the obtained uniaxially stretched separator is between 100-160MPa, and the puncture strength of the 16-20μm thick separator is In 263 ~ 315g. The present invention adopts the staged stretching method, pre-stretching before annealing and then conventional stretching, and pre-stretching at a pre-stretching ratio of 1.1 to 1.5 times and a pre-stretching temperature of 100-150°C The degree of orientation of the molecular chain is enhanced, so that the tensile strength and puncture strength of the separator are significantly improved after subsequent stretching, while other performance indicators of the separator remain at a good level. The pore size distribution of the lithium-ion battery separator obtained by the dry uniaxial stretching process of the present invention is uniform, the tensile strength is increased ...

Embodiment 1

[0118] A dry uniaxial stretching process for a lithium-ion battery diaphragm, comprising the following steps:

[0119] The polypropylene particles are plasticized by a 230°C extruder to form a polypropylene melt, and then extruded from a 210°C die, cast into a 23.8μm sheet polypropylene base film by a 70°C quenching roll, and harvested into a roll; The base film is pre-stretched at 130°C with a ratio of 1.3 and harvested into rolls; the rolled base film is pushed into an oven for heat treatment at 145°C for 8 hours; the heat-treated polyolefin base film is subjected to a single Lithium battery microporous separator can be obtained after stretching.

Embodiment 2

[0121] A dry uniaxial stretching process for a lithium-ion battery diaphragm, comprising the following steps:

[0122] The polypropylene particles are plasticized by a 228°C extruder to form a polypropylene melt, and then extruded from a 208°C die, cast into a 18.8μm sheet polypropylene base film by a 60°C quenching roll, and harvested into a roll; The base film is pre-stretched at 120°C with a ratio of 1.2 and harvested into a roll; the rolled base film is pushed into an oven for heat treatment at 140°C for 10 hours; the heat-treated polyolefin base film is subjected to a single Lithium battery microporous separator can be obtained after stretching.

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Abstract

The invention discloses a dry one-way drawing process of a lithium-ion battery separator, the lithium-ion battery separator and a lithium-ion battery and relates to the technical field of preparation of the lithium-ion battery separator. The dry one-way drawing process of the lithium-ion battery separator comprises the following steps that a polyolefin base film is subjected to pre-drawing before annealing treatment and subjected to secondary drawing after annealing treatment, wherein the drawing multiplying power of pre-drawing is 1.1-1.5 and the drawing temperature is 100-150 DEG C. The problems that as for traditional dry one-way drawing, the lithium-ion battery separator drawing strength and puncture strength are low, the drawing strength is 170-180 MPa at most, and the separator strength requirement cannot be met are solved. According to the separator dry one-way drawing process provided by the invention, as pre-drawing is performed before annealing, the drawing process is performed stage by stage; and by means of the process, the strengths of the lithium-ion battery separator subjected to dry one-way drawing can be improved, specifically, the drawing strength of the separator subjected to dry one-way drawing can be improved by 20-30%, and the puncture strength of the separator subjected to dry one-way drawing can be improved by 10-20%.

Description

technical field [0001] The invention relates to the technical field of preparation of lithium-ion battery diaphragms, in particular to a dry uniaxial stretching process for lithium-ion battery diaphragms, lithium-ion battery diaphragms and lithium-ion batteries. Background technique [0002] Lithium-ion batteries have the characteristics of high open circuit voltage, high energy ratio and large capacity. They have always been the power batteries favored by new energy vehicle manufacturers. In the structure of lithium-ion batteries, the diaphragm is one of the key inner components. The performance of the separator determines the interface structure and internal resistance of the battery, which directly affects the capacity, cycle and safety performance of the battery. A separator with excellent performance plays an important role in improving the overall performance of the battery. The tensile strength / puncture strength of the separator is one of the important indicators, and...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): B29C69/02B29C48/08B29C48/92B29C55/02B29C71/02B29L7/00
CPCB29C48/0018B29C48/08B29C48/92B29C55/02B29C71/02B29C2071/022B29C2948/92704B29L2007/00
Inventor 颜鸿彬刘孟权
Owner SHENZHEN SENIOR TECH MATERIAL
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