Coated lithium ion battery diaphragm

A technology for lithium-ion batteries and diaphragms, applied in the field of lithium-ion battery diaphragms and their preparation, can solve the problems of reduced porosity of diaphragms, lack of interaction, and reduced battery capacity, so as to avoid the reduction of micropores and coating peeling off , the effect of fast washing liquid speed

Active Publication Date: 2015-06-10
SHANGHAI SHUANGAO ENERGY TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, the current market mainly uses the method of coating organic and inorganic substances. Although various manufacturers are using different technologies to reduce the shielding effect of coating on the micropores of the original polyolefin separator, the coating method has determined the coating method. For example, the layer will block some of the micropores of the original separator, resulting in a decrease in the overall porosity of the separator and a decrease in the capacity of the assembled battery, which is contrary to the high capacity required by electric vehicles; in addition, due to the difference between the coating layer and the base film layer (polyolefin) Lack of sufficient interaction between them, it is easy to cause the overall peeling off of the coating

Method used

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Examples

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preparation example Construction

[0046] The preparation technology of coated lithium-ion battery diaphragm of the present invention comprises the following steps:

[0047] Step 1: basement membrane preparation, including the following steps:

[0048] 1) Add polyolefin, inorganic particles and plasticizer into the twin-screw extruder, and form a homogeneous phase by heating and shearing; the temperature during extrusion is preferably 150-250 degrees, and the screw speed is 100-600rpm.

[0049] 2) The mixture extruded by the twin-screw extruder passes through a coat hanger die to form a sheet, and is cooled on a cooling roll to form a thick film; the cooling roll can be used for single-side contact melt cooling or double-side contact melt cooling , the cooling roll temperature is preferably 0-50°C.

[0050] 3) By stretching in one direction or two directions, the stretching ratio is 9-50 times, and the thick film is stretched into a film; the stretching temperature is 80-130°C, preferably 90-125°C, and the str...

Embodiment 1

[0058] 1. Base film preparation: Extrude 20 parts of ultra-high molecular weight polyethylene with a molecular weight of 1 million, 10 parts of silicon dioxide with a particle size of 50 nm, and 70 parts of paraffin oil through a twin-screw extruder at a temperature of 220 ° C. The temperature of the cooling roll was 25° C., and a thick film with a thickness of 1000 μm was obtained. Enter the biaxial stretching machine to stretch 7 times in the longitudinal direction and transverse direction, and the stretching temperature is 120°C. The stretched film enters the heptane tank and stays for 10 minutes. After extraction, it enters the transverse stretching machine, stretches 1.2 times in the transverse direction and then retracts to 1.05 times, and the transverse stretching temperature is 130°C. Finally, after heat treatment, the heat treatment temperature is 130 ° C, and the treatment time is 5 minutes.

[0059] 2. Coating: Dissolve 10% PVDF-CTFE (polyvinylidene fluoride-chlor...

Embodiment 2

[0062] 1. Base film preparation: Extrude 15 parts of ultra-high molecular weight polyethylene with a molecular weight of 1 million, 15 parts of silicon dioxide with a particle size of 50 nm, and 70 parts of paraffin oil through a twin-screw extruder at a temperature of 220 ° C. The temperature of the cooling roll was 25° C., and a thick film with a thickness of 1000 μm was obtained. Enter the biaxial stretching machine to stretch 7 times in the longitudinal direction and transverse direction, and the stretching temperature is 120°C. The stretched film enters the heptane tank and stays for 10 minutes. After extraction, it enters the transverse stretching machine, stretches 1.2 times in the transverse direction and then retracts to 1.05 times, and the transverse stretching temperature is 130°C. Finally, after heat treatment, the heat treatment temperature is 130 ° C, and the treatment time is 5 minutes.

[0063] 2. Coating: Dissolve 10% PVDF-CTFE in acetone, stir and disperse ...

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Abstract

The invention discloses a coated lithium ion battery diaphragm. The coated lithium ion battery diaphragm is formed by a basal diaphragm and a coating layer on the surface of the basal diaphragm, wherein the basal diaphragm comprises polyolefin and inorganic substance particles, and the porosity of the basal diaphragm is 60-90%; and the coating layer comprises inorganic substance particles and a binder, and the porosity of the coating layer is 30-60%. The preparation method of the coated lithium ion battery diaphragm comprises the following steps of preparing, coating and drying the basal diaphragm. In the heat treatment process of the basal diaphragm preparation, the heat treatment temperature is 100-(the melting point of polyolefin+70) DEG C, and the heat treatment time is 0.5-6min. The coating process comprises the steps of mixing and stirring inorganic substances, the binder and a solvent according to the set proportion to form uniform slurry; coating the slurry on one side or two sides of the basal diaphragm, wherein the coating thickness of one side is 2-10microns; and finally obtaining the lithium ion battery diaphragm. The lithium ion battery diaphragm has high porosity and favorable high temperature heat resistance performance, and the surface porosity of the diaphragm is lower than the central porosity.

Description

technical field [0001] The invention relates to the field of lithium ion batteries, in particular to a lithium ion battery diaphragm and a preparation method thereof. Background technique [0002] In the structure of lithium batteries, the separator 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. [0003] The main function of the diaphragm is to separate the positive and negative electrodes of the battery, prevent the two electrodes from contacting and short circuit, and also have the function of allowing electrolyte ions to pass through. The separator material is non-conductive, and its physical and chemical properties have a great influence on the performance of the battery. Differe...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H01M10/0525H01M2/14
CPCY02E60/10
Inventor 赵海玉石品品范海平吴爱文吴群伟
Owner SHANGHAI SHUANGAO ENERGY TECH
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