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High-puncture-strength lithium ion battery diaphragm and preparation method thereof

A lithium-ion battery, puncture strength technology, applied in secondary batteries, battery pack parts, separators/films/diaphragms/spacers and other directions, can solve the problems of low lateral strength, micro-short circuit, easy to tear , to achieve the effect of improving puncture resistance, impact resistance, and eliminating the problem of micro-short circuit

Inactive Publication Date: 2014-03-12
SHENZHEN SENIOR TECH MATERIAL
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0003] The technology of dry uniaxial stretching to prepare lithium-ion battery separators has also developed rapidly in recent years. The forming principle is that a polymer melt with a certain structure is unidirectionally extruded under certain conditions. In the extrusion direction, The polymer is stressed to form a highly oriented structure. In the direction perpendicular to the extrusion direction, because there is no orientation, the wafers are only supported by van der Waals force. This microstructure is formed after annealing and stretching along the extrusion direction. Microporous membrane, the microporous membrane is highly oriented in the longitudinal direction (extrusion stretching direction), with high strength (greater than 100MPa), but the tensile strength in the transverse direction (perpendicular to the extrusion stretching direction) is very small (about 10-15MPa ), although there is no stretch orientation in the transverse direction, the thermal shrinkage in the transverse direction is small, and the transverse shrinkage is not easy to occur in the battery, which is an advantage of the dry unidirectional stretch film, but the transverse strength is small, and it is easy to tear when the battery is assembled What is more serious is that under certain conditions, lithium-ion electrolytes are prone to generate lithium dendrites in the battery. Lithium dendrites are relatively sharp, and they are easy to pierce through the diaphragm with low lateral strength, resulting in micro-short circuit, resulting in battery failure. Self-discharge or cause a safety accident

Method used

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  • High-puncture-strength lithium ion battery diaphragm and preparation method thereof

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Embodiment 1

[0029] This embodiment provides a lithium-ion battery separator with high puncture strength, the main raw material is polypropylene resin, and the auxiliary materials are phthalate plasticizer dioctyl phthalate and phenolic antioxidant 2, 6-di-tert-butyl-4-methylphenol, the thickness of the microporous membrane is 16 μm, and the porosity is 36%. The content of the main resin polypropylene is 96% by mass percentage, and the content of the phthalate plasticizer dioctyl phthalate and the phenolic antioxidant 2,6-di-tert-butyl-4-methylphenol is as follows: The mass percentages are calculated as 2% and 2%, respectively.

[0030] In other embodiments, the main olefin resin is selected from one or more of polypropylene, polyethylene, polyvinylidene fluoride, and polyacrylonitrile, and the auxiliary additives are selected from plasticizers, fillers, reinforcing agents, flame retardants, and antioxidants. , one or more of antistatic agents and slip agents, among which the specific pla...

Embodiment 2

[0040]This embodiment provides a lithium-ion battery separator with high puncture strength, its main raw material is polypropylene resin, and its auxiliary materials are phthalate plasticizer dioctyl phthalate, phenolic antioxidant tetra[ 3-(3',5'-di-tert-butyl-4-hydroxyphenyl) propionate] pentaerythritol ester, the thickness of the microporous membrane is 16 μm, and the porosity is 40%. The content of main resin polypropylene is 96% by mass percentage, phthalate plasticizer dioctyl phthalate, phenolic antioxidant tetrakis[3-(3′,5′-di-tert-butyl- The content of 4-hydroxyphenyl) propionate] pentaerythritol ester is calculated as 2% and 2% respectively according to mass percentage.

[0041] The method of preparing a high-puncture-strength lithium-ion battery separator is basically the same as that of Example 1. The main change is that in the sixth step of transverse stretching, the temperature of transverse stretching is changed to 135°C;

Embodiment 3

[0043] This embodiment provides a lithium-ion battery separator with high puncture strength. The main raw material is polypropylene resin, and the auxiliary materials are pentaerythritol ester, antioxidant tetrakis [3-(3′,5′-di-tert-butyl-4 -Hydroxyphenyl) propionate] pentaerythritol ester and dilauryl thiodipropionate, the thickness of the microporous membrane is 16 μm, and the porosity is 45%. The content of main resin polypropylene is 96% by mass percentage, pentaerythritol ester, antioxidant tetrakis[3-(3′,5′-di-tert-butyl-4-hydroxyphenyl) propionate] pentaerythritol ester and dithiodiol The content of dilauryl propionate is calculated as 2% and 2% respectively by mass percentage.

[0044] The method for preparing a high-puncture-strength lithium-ion battery separator is basically the same as in Example 1. The main changes are that in the sixth step of transverse stretching, the temperature of transverse stretching is changed to 135°C, and the stretching ratio is changed t...

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Abstract

The invention relates to the processing field of lithium ion battery diaphragms and discloses a high-puncture-strength lithium ion battery diaphragm. The high-puncture-strength lithium ion battery diaphragm consists of 75 to 99.9 weight percent of main body olefin resin and 25 to 0.1 weight percent of an auxiliary additive. The invention further discloses a method for preparing the high-puncture-strength lithium ion battery diaphragm, which comprises the following step: carrying out transverse stretching on a micropore diaphragm which is longitudinally stretched, wherein the traveling speed of the micropore diaphragm is 0.5 to 200 mm / min, the stretch temperature is 100 to 150 DEG C and the stretching multiplying power is 0.5 to 3.0. According to the invention, one step of transversely stretching is added on the basis of one-way stretching in an existing dry method; and by transverse stretching according to a certain ratio, under the condition of not influencing basic performance of the micropore diaphragm (air permeability, porosity and the like), the transverse intensity of the micropore diaphragm is improved, i.e. the puncture-resistant intensity of the micropore diaphragm is improved, so that the diaphragm can be better suitable for assembling of a battery, the micro short circuit problem caused by lithium dendrite puncture is reduced or avoided and safety of the battery is improved.

Description

technical field [0001] The invention relates to the field of processing lithium-ion battery separators, in particular to a high-puncture-strength lithium-ion battery separator capable of improving the transverse strength of a microporous membrane and thereby improving battery safety and a preparation method thereof. Background technique [0002] With the continuous expansion of the application field of lithium batteries and the deepening influence of lithium battery products in people's lives, people's requirements for the performance of lithium batteries are also getting higher and higher. In order to meet the development requirements of lithium batteries, the diaphragm, as an important part of lithium batteries, should not only have good chemical stability and low manufacturing cost, but also improve the safety performance of lithium-ion batteries is an important trend in the current development of lithium batteries. [0003] The technology of dry uniaxial stretching to pr...

Claims

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Application Information

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IPC IPC(8): H01M2/16H01M50/403H01M50/417H01M50/489H01M50/494
CPCH01M10/0525H01M50/403H01M50/409H01M50/411Y02E60/10
Inventor 杨雪梅蒋坤王今刚陈良
Owner SHENZHEN SENIOR TECH MATERIAL
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