Polyolefin multilayer micro porous diaphragm for lithium ion battery and preparation method of polyolefin multilayer micro porous diaphragm

A technology of lithium-ion batteries and microporous membranes, which is applied in the field of diaphragm materials for lithium-ion batteries and its preparation, can solve the problems of reducing the porosity of diaphragms, poor cycle life and safety performance, and poor battery safety performance. Effects of discharge power and cycle life, good liquid absorption and retention, excellent lyophilicity and adhesion

Active Publication Date: 2014-01-22
河南惠强新能源材料科技股份有限公司
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Coating improvement on a single-layer PE or PP film will cause coating peeling and pore blocking, which reduces the porosity of the separator, which is not conducive to high-current charging and discharging, and its cycle life and safety performance are poor.
If the porosity is increased, the thermal shrinkage performance of the separator will be deteriorated, and the safety performance of the battery will be poor
Good thermal stability can be obtained by compounding PE and PP, but the three-layer composite separator currently mainly used has the problems of low porosity, small pore size, poor lyophilicity, low interfacial peel strength, and high impedance, which cannot meet the requirements of power lithium at the same time. Ion battery high power demand

Method used

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  • Polyolefin multilayer micro porous diaphragm for lithium ion battery and preparation method of polyolefin multilayer micro porous diaphragm
  • Polyolefin multilayer micro porous diaphragm for lithium ion battery and preparation method of polyolefin multilayer micro porous diaphragm
  • Polyolefin multilayer micro porous diaphragm for lithium ion battery and preparation method of polyolefin multilayer micro porous diaphragm

Examples

Experimental program
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Effect test

Embodiment 1

[0064] Preparation of polyethylene microporous layer: Take 20% by weight high-density polyethylene and 80% liquid paraffin and extrude in a twin-screw extruder at 200 ° C, form an oil film on a cooling roll at 25 ° C, and heat the above oil film at 120 ° C Two-way simultaneous stretching is carried out, the stretching ratio is 5×5, and the stretched oil film is subjected to heat setting treatment at 130°C for 20s. The high-boiling-point solvent in the solvent is eluted with dichloromethane extractant, and then dried to obtain a polyethylene microporous layer.

[0065] Preparation of the polypropylene microporous layer: the polypropylene was melt-extruded at 230° C. with an extrusion device, and then cooled to 90° C. for uniaxial stretching to obtain a polypropylene microporous layer.

[0066] Preparation of ion acceleration layer: Add polyvinylidene fluoride to acetone: glycerol = 10: 1 mixed solution, and prepare ion acceleration layer solution according to the mass ratio pol...

Embodiment 2

[0069] Preparation of polyethylene microporous layer: Take 20% by weight high-density polyethylene and 80% liquid paraffin and extrude in a twin-screw extruder at 200 ° C, form an oil film on a cooling roll at 25 ° C, and heat the above oil film at 120 ° C Carry out two-way simultaneous stretching with a stretching ratio of 5×5, and heat-setting the stretched oil film at 130°C for 20s. The high-boiling-point solvent in the solvent is eluted with dichloromethane extractant, and then dried to obtain a polyethylene microporous membrane.

[0070] Preparation of the polypropylene microporous layer: the polypropylene was melt-extruded at 230° C. with an extrusion device, and then cooled to 90° C. for uniaxial stretching to obtain a polypropylene microporous layer.

[0071] Preparation of the ion acceleration layer: Add polyvinylidene fluoride and dioctyl phthalate to acetone, and prepare according to the mass ratio of polyvinylidene fluoride: dioctyl phthalate: acetone = 1:0.1:12 i...

Embodiment 3

[0074] Preparation of polyethylene microporous layer: Take 20% by weight high-density polyethylene and 80% liquid paraffin and extrude in a twin-screw extruder at 200 ° C, form an oil film on a cooling roll at 25 ° C, and heat the above oil film at 120 ° C Carry out two-way simultaneous stretching with a stretching ratio of 5×5, and heat-setting the stretched oil film at 130°C for 20s. The high-boiling-point solvent in the solvent is eluted with dichloromethane extractant, and then dried to obtain a polyethylene microporous membrane.

[0075] Preparation of the polypropylene microporous layer: the polypropylene was melt-extruded at 230° C. with an extrusion device, and then cooled to 90° C. for uniaxial stretching to obtain a polypropylene microporous layer.

[0076] Preparation of ion acceleration layer: Add polyvinylidene fluoride to acetone: glycerol = 10: 1 mixed solution, and prepare ion acceleration layer solution according to the mass ratio polyvinylidene fluoride: mixed ...

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Abstract

The invention relates to a polyolefin multilayer micro porous diaphragm for a lithium ion battery and a preparation method of the polyolefin multilayer micro porous diaphragm. The polyolefin multilayer micro porous diaphragm comprises a polyethylene micro porous layer, wherein an ion acceleration layer is arranged on each of the upper surface and the lower surface of the polyethylene micro porous layer, and a polypropylene micro porous layer is arranged on the outer surface of each ion acceleration layer. According to the polyolefin multilayer micro porous diaphragm, due to the adoption of a five-layer structure, a low hole closing temperature and a high diaphragm breaking temperature of the diaphragm can be provided, thus a safety window of the diaphragm is increased and the good safety performance is provided; and meanwhile, the ion acceleration layers provide low resistance, high electron conduction rate and good solution absorption performance and solution maintaining performance of the diaphragm, thus the charge-discharge power and the cycle service life of the lithium ion battery can be improved; and the ion acceleration layers have micro porous net-shaped structures and have excellent lyophilic performance and adhering performance, the ion transmission performance of the diaphragm is improved when all layers of the multilayer micro porous diaphragm are well compounded, and good gas permeability is kept.

Description

technical field [0001] The invention relates to a diaphragm material for lithium ion batteries and a preparation method thereof, in particular to a polyolefin multilayer microporous film applied to electrochemical energy storage devices such as lithium ion secondary batteries and a preparation method thereof. Background technique [0002] The lithium-ion battery separator is one of the important components of the lithium-ion battery that is used in the lithium-ion battery to isolate the positive and negative electrodes to prevent battery short circuit and has a certain pore structure to ensure the smooth passage of lithium ions. This separator can be used in lithium-ion batteries for communications such as electronic products and electrical equipment. In recent years, research on lithium secondary batteries as power sources for electric vehicles and hybrid vehicles has been carried out. This type of high-end lithium-ion batteries requires high power output, high capacity, ex...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H01M2/16H01M2/18H01M50/403H01M50/417H01M50/457H01M50/491
CPCH01M50/403H01M50/449Y02E60/10
Inventor 王松钊林妙云吴耀根蔡朝辉廖凯明
Owner 河南惠强新能源材料科技股份有限公司
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