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Diaphragm, preparation method thereof, secondary battery and electric equipment

A diaphragm and base film technology, applied in secondary batteries, battery pack components, circuits, etc., can solve problems such as poor shrinkage performance, inability to meet low shrinkage and high membrane rupture temperature at the same time, and inability to further improve the safety performance of the diaphragm

Pending Publication Date: 2021-11-02
HUAWEI TECH CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The heat resistance of the diaphragm is reflected in the integrity at high temperature (no shrinkage at high temperature) and high temperature strength (no damage at high temperature, generally reflected by the rupture temperature, where the rupture temperature is the temperature when the diaphragm structure ruptures at high temperature), However, the existing diaphragm can improve the high-temperature strength of the diaphragm by coating a heat-resistant coating, but its shrinkage performance is poor, and the shrinkage rate is often greater than 5%; by coating an organic-inorganic composite coating, although the diaphragm can be improved Shrinkage performance, but the membrane rupture temperature of the obtained separator is generally lower than 220°C, and the safety performance of the separator cannot be further improved
Therefore, the current separator cannot meet the requirements of low shrinkage and high membrane rupture temperature at the same time at high temperature.

Method used

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  • Diaphragm, preparation method thereof, secondary battery and electric equipment
  • Diaphragm, preparation method thereof, secondary battery and electric equipment
  • Diaphragm, preparation method thereof, secondary battery and electric equipment

Examples

Experimental program
Comparison scheme
Effect test

preparation example Construction

[0077] The preparation process of the base film will be described below. It can be understood that the following preparation method is only an optional preparation method of the base film, and the preparation method of the base film is not limited to the following preparation methods.

[0078] Figure 4 For the preparation method of the base film of a kind of embodiment of the present application, such as Figure 4 As shown, as an illustration, in one embodiment of the present application, the preparation method of the base film includes the following steps:

[0079] Step S11, mixing the polyolefin resin raw material and solvent to obtain a mixed melt: melt and knead the polyolefin resin raw material, solvent and additives in a twin-screw extruder to form a uniform liquid phase; wherein, the boiling point of the solvent higher than the mixing temperature.

[0080] Among them, the polyolefin resin raw material is designed according to the required functions of the polyolefin...

Embodiment 1

[0125] The application is a lithium ion battery, and the specific raw materials and preparation process of the lithium ion battery are as follows:

[0126] Step (1) Base Membrane (A): Preparation of Polyolefin Porous Membrane

[0127] Polyolefin composition: Ultra-high molecular weight polyethylene with a melting point of 136°C and a molecular weight of 1 million, low-melting polyethylene with a melting point of 125°C and a molecular weight of 600,000; polypropylene with a melting point of 165°C and a molecular weight of 500,000 in a ratio of 55:30:15 Ratio and paraffin oil are melted and mixed at high temperature in a twin-screw extruder, the ratio of polyolefin composition to paraffin oil is 25:75, the mixing temperature is 190-220°C, and the homogeneous melt passes through a slot die Head extrusion, casting on cooling rollers to form a gel sheet, the cooling rate is 85°C / min; then the gel sheet is first stretched 5 times in the MD direction, and then stretched 5 times in th...

Embodiment 2-47

[0139] Examples 2 to 47 are respectively a lithium ion battery, and the preparation method of the separator is referred to in Example 1. The specific raw materials and structural parameters of the separator are listed in Table 1.

[0140] Among them, in the lithium-ion battery of Examples 42-47, the diaphragm also includes the step of coating an adhesive layer after coating the organic coating during the preparation process. The specific coating process of the adhesive layer is as follows: the adhesive resin PVDF Dissolve in good solvent N-methylpyrrolidone to form a mixed solution with a concentration of 3%, and then disperse alumina inorganic particles in the above mixed solution to form a coating slurry, wherein the mass ratio of PVDF to alumina is 60%: 40%. The uniformly dispersed slurry is coated on the diaphragm obtained in step (3) by gravure reverse roller coating on both sides at the same time, and the diaphragm covered with the adhesive layer is obtained after coagul...

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Abstract

The invention provides a diaphragm, a preparation method thereof, a secondary battery and electric equipment. The diaphragm comprises a base film, at least one inorganic coating and at least one organic coating, the base film, the inorganic coating and the organic coating are laminated, at least one side surface of the base film is in contact with the inorganic coating, the organic coating contains organic heat-resistant resin, and the lower one of the melting point and the decomposition temperature of the organic heat-resistant resin is greater than or equal to 200 DEG C. The diaphragm with the structure can improve the high-temperature shrinkage performance of the diaphragm while increasing the diaphragm rupture temperature of the diaphragm.

Description

technical field [0001] The present application relates to the field of batteries, in particular to a diaphragm, a preparation method thereof, a secondary battery and electrical equipment. Background technique [0002] At present, secondary batteries have been widely used in consumer terminal equipment such as mobile phones, notebooks, wearable devices, mobile power supplies, electric vehicles and energy storage fields. However, secondary battery failure accidents occur frequently, and its safety performance has become a key research direction . The failure of the secondary battery is mainly manifested as smoke, fire, combustion, and explosion caused by thermal runaway. The main causes of thermal runaway are mechanical collision, overcharge / overdischarge, high temperature overheating, etc., which lead to short circuit inside the secondary battery. When a short circuit occurs inside the secondary battery, it will further cause the diaphragm to shrink or be damaged at high te...

Claims

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Application Information

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IPC IPC(8): H01M50/451H01M50/457H01M50/403H01M10/0525H01M10/054
CPCH01M50/451H01M50/457H01M50/403H01M10/0525H01M10/054Y02E60/10
Inventor 张新枝邓耀明
Owner HUAWEI TECH CO LTD
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