CN112086610A - Asymmetric PVDF (polyvinylidene fluoride) coated diaphragm and preparation method thereof - Google Patents

Asymmetric PVDF (polyvinylidene fluoride) coated diaphragm and preparation method thereof Download PDF

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CN112086610A
CN112086610A CN202011049961.3A CN202011049961A CN112086610A CN 112086610 A CN112086610 A CN 112086610A CN 202011049961 A CN202011049961 A CN 202011049961A CN 112086610 A CN112086610 A CN 112086610A
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pvdf
coating
slurry
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CN112086610B (en
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张立斌
李正林
翁星星
陈朝晖
贡晶晶
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Jiangsu Housheng New Energy Technology Co Ltd
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Jiangsu Housheng New Energy Technology Co Ltd
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/052—Li-accumulators
    • H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries

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  • General Chemical & Material Sciences (AREA)
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Abstract

The invention discloses an asymmetric PVDF (polyvinylidene fluoride) coated diaphragm and a preparation method thereof. The coating membrane comprises a base material and PVDF slurry; the PVDF slurry also comprises a first PVDF slurry and a second PVDF slurry; the first PVDF slurry is coated on the upper surface of the base material to form a first PVDF coating; the second PVDF slurry is coated on the lower surface of the base material to form a second PVDF coating; the adhesive force of the second PVDF coating is greater than that of the first PVDF coating; the invention prepares an asymmetric PVDF coating diaphragm through different coating compositions and manufacturing processes, the bonding force of two sides of the diaphragm is different, and the invention can match the difference of the surfaces of the positive and negative pole pieces of the battery, so that the bonding force of the diaphragm and the positive and negative pole pieces of the battery is kept consistent, the consistency of the battery is improved, the electrical property of the battery is ensured, and the cycle life and the charging and discharging efficiency of the battery are improved.

Description

Asymmetric PVDF (polyvinylidene fluoride) coated diaphragm and preparation method thereof
Technical Field
The invention relates to the technical field of lithium battery diaphragms, in particular to an asymmetric PVDF (polyvinylidene fluoride) coated diaphragm and a preparation method thereof.
Background
Lithium ion batteries are increasingly used in the field of power, such as electric vehicles; the method is applied to the 3C field, such as mobile phones and tablet computers; the electric tool is applied to the field of electric tools, such as various handheld electric tools. Along with the expansion of the application range, the market has higher and higher requirements on the performance of the lithium ion battery, and further, higher requirements are provided for the lithium ion battery diaphragm.
The lithium ion battery comprises four parts, namely an anode, a cathode, a diaphragm and electrolyte, wherein the diaphragm is positioned between the anode and the cathode and mainly used for separating the anode and the cathode to avoid short circuit in the battery and simultaneously providing a lithium ion channel to allow lithium ions to pass through in the charging and discharging processes of the battery. In the process of charging and discharging the lithium ion battery, a gap is generated between the diaphragm and the anode and the cathode, so that the performance of the battery is sharply reduced; at present, the mainstream solution is to coat PVDF on both sides of the diaphragm, so as to improve the adhesion of the diaphragm with the anode and the cathode and reduce the occurrence of the phenomenon. However, the main solution does not consider the difference between the surfaces of the positive electrode and the negative electrode, and thus the adhesion between the prepared PVDF-coated separator and the positive electrode and the negative electrode is different, so that the PVDF-coated separator is likely to fail on the side with poor adhesion, and the electrical performance of the battery is reduced.
Disclosure of Invention
The invention aims to provide an asymmetric PVDF coating membrane and a preparation method thereof, which are used for solving the problems in the background technology.
In order to solve the technical problems, the invention provides the following technical scheme: an asymmetric PVDF coated membrane and a preparation method thereof.
An asymmetric PVDF-coated separator comprising a substrate, a PVDF slurry; the PVDF sizing agent is respectively coated on the upper surface and the lower surface of the base material.
Further, the PVDF slurry comprises the following raw material components: 1-30% of PVDF monomer, 1-20% of adhesive, 1-15% of auxiliary agent and 60-95% of deionized water by mass fraction.
Further, the base material is one of a polyolefin diaphragm, a polyolefin composite diaphragm and a PET diaphragm;
further, a ceramic coating can be coated on one side or both sides of the substrate;
further, the PVDF slurry also comprises a first PVDF slurry and a second PVDF slurry; the first PVDF slurry is coated on the upper surface of the base material to form a first PVDF coating; and the second PVDF slurry is coated on the lower surface of the base material to form a second PVDF coating. The adhesion of the second PVDF coating is greater than the adhesion of the first PVDF coating.
Further, the first PVDF sizing agent comprises the following raw material components: 1-10% of PVDF monomer, 1-5% of adhesive, 0.1-10% of auxiliary agent and 75-90% of deionized water in percentage by mass.
Further, the second PVDF slurry comprises the following raw material components: 10-20% of PVDF monomer, 3-10% of adhesive, 0.1-10% of auxiliary agent and 75-86.9% of deionized water in percentage by mass.
Further, the mass ratio of the PVDF monomer to the adhesive in the first PVDF coating is P1, the mass ratio of the PVDF monomer to the adhesive in the second PVDF coating is P2, and the relationship between P1 and P2 satisfies the following conditions: p1 is more than or equal to 2 and more than or equal to P2 and more than or equal to 50.
The mass ratio of the PVDF monomer to the adhesive is a formula ratio, when the mass ratio of the PVDF monomer to the adhesive is larger, the adhesive force between the PVDF monomer and the base material is reduced, and the ventilation increment of the coating is smaller; when the quality of the PVDF monomer and the adhesive is smaller, the adhesive force between the PVDF monomer and the base material is increased, and the ventilation increment of the coating is larger.
Further, the first PVDF coating has an area density of M1, and the second PVDF coating has an area density of M2; the areal density relationship of the first PVDF coating and the second PVDF coating is as follows: 0.1g/m2≤M1＜M2≤2g/m2。
The larger the surface density of the PVDF coating is, the larger the adhesive force between the coated diaphragm and the positive and negative plates of the battery is, the first PVDF slurry and the second PVDF slurry with different adhesive forces are prepared by controlling the using amount of each component of the PVDF slurry and are respectively coated on the upper surface and the lower surface of a base material to form the coated diaphragm; the surface densities of the coatings on the two sides of the prepared coated diaphragm are different, and the bonding forces on the two sides of the coated diaphragm are asymmetric, so that the surface differences of the positive and negative pole pieces are matched, the bonding forces of the diaphragm and the positive and negative pole pieces are kept consistent, the consistency of the battery is improved, and the electrical property of the battery is kept.
Further, the particle size of the PVDF monomer is 0.1-1 μm; the adhesive is one or more of poly (methyl) acrylic acid, poly (methyl) acrylate, polyvinyl acetate, butadiene-styrene copolymer, styrene-acrylate copolymer, ethylene-ethyl acetate copolymer, polyacrylonitrile, polyurethane and polyvinyl alcohol.
A method for preparing an asymmetric PVDF coated membrane comprises the following steps:
(1) preparing PVDF slurry:
A. preparing a first PVDF slurry;
B. preparing a second PVDF slurry;
(2) coating a separator:
A. selecting a base material, coating the second PVDF slurry on the lower surface of the base material at the speed of 20-100m/min to obtain a second PVDF coating, and drying the second PVDF coating twice at the temperature of 40-80 ℃ to obtain a diaphragm A;
B. and coating the first PVDF slurry on the upper surface of the substrate at the speed of 20-100m/min to obtain a first PVDF coating, and drying the first PVDF coating once at the temperature of 40-80 ℃ to obtain the asymmetric PVDF coated membrane.
When the conventional process is used for preparing the coating diaphragm, a layer of the coating diaphragm is generally dried only once, while the invention carries out two drying operations in the process of preparing the second PVDF coating and only carries out one drying operation in the process of preparing the first PVDF coating; the purpose of performing two drying operations is to enable the adhesive to be dried and cured more fully and to have stronger adhesive force on one hand, and on the other hand, the asymmetry of the adhesive force between the two coatings is constructed through the difference of the drying times between the first PVDF coating and the second PVDF coating.
Further, the drying temperature of the step A in the step (2) is T1, the drying temperature of the step B in the step (2) is T2, and the relation between T1 and T2 is as follows: t1 is more than or equal to 40 ℃ and T2 is more than or equal to 80 ℃.
Compared with the prior art, the invention has the following beneficial effects:
the invention prepares an asymmetric PVDF coating diaphragm through different coating compositions and manufacturing processes, the bonding force of two sides of the diaphragm is different, and the invention can match the difference of the surfaces of the positive and negative pole pieces of the battery, so that the bonding force of the diaphragm and the positive and negative pole pieces of the battery is kept consistent, the consistency of the battery is improved, the electrical property of the battery is ensured, and the cycle life and the charging and discharging efficiency of the battery are improved.
The invention provides a novel solution, and an asymmetric PVDF coated diaphragm is prepared through different coating compositions and manufacturing processes, wherein the bonding forces on two sides of the diaphragm are different, so that the difference of the surfaces of a positive electrode and a negative electrode can be matched, the bonding forces of the diaphragm and the positive electrode and the negative electrode are kept consistent, the consistency of a battery is improved, and the electrical property of the battery is ensured.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
Example 1
(1) Preparing PVDF slurry:
A. preparing a first PVDF slurry: mixing 1% of binder, 86% of deionized water, 8% of PVDF monomer and 5% of auxiliary agent to obtain a first PVDF slurry;
B. preparing a second PVDF slurry: mixing 3% of binder, 86.9% of deionized water, 10% of PVDF monomer and 0.1% of auxiliary agent to obtain second PVDF slurry;
(2) coating a separator:
A. selecting a base material, coating the second PVDF slurry on the lower surface of the base material at the speed of 80m/min to obtain a second PVDF coating, drying the second PVDF coating twice at the temperature of 60 ℃, and drying for 30s once to obtain a diaphragm A; areal density of the second PVDF coatingIs 0.5g/m2；
B. Coating the first PVDF slurry on the upper surface of a base material at a speed of 80m/min to obtain a first PVDF coating, and drying the first PVDF coating at the temperature of 60 ℃ for 30s to obtain an asymmetric PVDF coated diaphragm; the areal density of the first PVDF coating was 0.5g/m2。
Example 2
(1) Preparing PVDF slurry:
A. preparing a first PVDF slurry: mixing 3% of binder, 90% of deionized water, 1% of PVDF monomer and 6% of auxiliary agent to obtain first PVDF slurry;
B. preparing a second PVDF slurry: mixing 3% of binder, 75% of deionized water, 20% of PVDF monomer and 2% of auxiliary agent to obtain second PVDF slurry;
(2) coating a separator:
A. selecting a base material, coating the second PVDF slurry on the lower surface of the base material at the speed of 80m/min to obtain a second PVDF coating, drying the second PVDF coating twice at the temperature of 60 ℃, and drying for 30s once to obtain a diaphragm A; the second PVDF coating had an areal density of 0.5g/m2；
B. Coating the first PVDF slurry on the upper surface of a base material at a speed of 80m/min to obtain a first PVDF coating, and drying the first PVDF coating at the temperature of 60 ℃ for 30s to obtain an asymmetric PVDF coated diaphragm; the areal density of the first PVDF coating was 0.5g/m2。
Example 3
(1) Preparing PVDF slurry:
A. preparing a first PVDF slurry: 5% of binder, 90% of deionized water, 0.1% of PVDF monomer and 4.9% of auxiliary agent are mixed to obtain a first PVDF slurry;
B. preparing a second PVDF slurry: 5% of binder, 75% of deionized water, 10% of PVDF monomer and 10% of auxiliary agent are mixed to obtain a second PVDF slurry;
(2) coating a separator:
A. selecting a base material, coating the second PVDF slurry on the lower surface of the base material at the speed of 80m/min to obtain a second PVDF coating, drying the second PVDF coating twice at the temperature of 60 ℃, and drying for 30s once to obtain a diaphragm A; the second PVDF coating had an areal density of 0.5g/m2；
B. Coating the first PVDF slurry on the upper surface of a base material at a speed of 80m/min to obtain a first PVDF coating, and drying the first PVDF coating at the temperature of 60 ℃ for 30s to obtain an asymmetric PVDF coated diaphragm; the areal density of the first PVDF coating was 0.5g/m2。
Example 4
(1) Preparing PVDF slurry:
A. preparing a first PVDF slurry: 5% of binder, 75% of deionized water, 10% of PVDF monomer and 10% of auxiliary agent are mixed to obtain a first PVDF slurry;
B. preparing a second PVDF slurry: 8% of binder, 77% of deionized water, 10% of PVDF monomer and 5% of auxiliary agent are mixed to obtain a second PVDF slurry;
(2) coating a separator:
A. selecting a base material, coating the second PVDF slurry on the lower surface of the base material at the speed of 80m/min to obtain a second PVDF coating, drying the second PVDF coating twice at the temperature of 60 ℃, and drying for 30s once to obtain a diaphragm A; the second PVDF coating had an areal density of 0.5g/m2；
B. Coating the first PVDF slurry on the upper surface of a base material at a speed of 80m/min to obtain a first PVDF coating, and drying the first PVDF coating at the temperature of 60 ℃ for 30s to obtain an asymmetric PVDF coated diaphragm; the areal density of the first PVDF coating was 0.5g/m2。
Example 5
(1) Preparing PVDF slurry:
A. preparing a first PVDF slurry: mixing 1% of binder, 86% of deionized water, 8% of PVDF monomer and 5% of auxiliary agent to obtain first PVDF slurry;
B. preparing a second PVDF slurry: mixing 10% of binder, 75% of deionized water, 10% of PVDF monomer and 5% of auxiliary agent to obtain second PVDF slurry;
(2) coating a separator:
A. selecting a base material, coating the second PVDF slurry on the lower surface of the base material at the speed of 80m/min to obtain a second PVDF coating, drying the second PVDF coating twice at the temperature of 60 ℃, and drying for 30s once to obtain a diaphragm A; the second PVDF coating had an areal density of 0.5g/m2；
B. Coating the first PVDF slurry on the upper surface of a base material at a speed of 80m/min to obtain a first PVDF coating, and drying the first PVDF coating at the temperature of 60 ℃ for 30s to obtain an asymmetric PVDF coated diaphragm; the areal density of the first PVDF coating was 0.5g/m2。
Experiment 1: examples 1 to 5 as comparative examples, the second PVDF coating layer coated with the separator prepared in examples 1 to 5 was contacted with the positive electrode sheet of the battery, the first PVDF coating layer coated with the separator was contacted with the negative electrode sheet of the battery, and a wide sample bar was obtained by hot pressing; and then respectively taking sample bars with the width of 15mm, and testing the 180-degree peel strength of the diaphragm and the pole piece. Hot pressing temperature: 90 ℃; hot-pressing strength: 1.4 MPa; hot pressing time is 100 s; stripping speed: 50 mm/min.
The specific test results are shown in table 1:
table 1.
Figure BDA0002709246130000061
The data in table 1 show that the adhesive force between the coated diaphragm and the positive and negative electrode plates of the battery is increased along with the increase of the proportion of the adhesive in the first PVDF slurry and the second PVDF slurry; the adhesive force between the coating diaphragm and the positive and negative pole pieces of the battery is different; when the proportion of the adhesive in the second PVDF coating is larger than that of the adhesive in the first PVDF coating, the difference of the adhesive force between the coated diaphragm and the positive and negative pole pieces of the battery is reduced and tends to be equal.
Example 6
(1) Preparing PVDF slurry:
A. preparing a first PVDF slurry: 5% of binder, 90% of deionized water, 0.1% of PVDF monomer and 4.9% of auxiliary agent are mixed to obtain a first PVDF slurry;
B. preparing a second PVDF slurry: 5% of binder, 75% of deionized water, 10% of PVDF monomer and 10% of auxiliary agent are mixed to obtain a second PVDF slurry;
(2) coating a separator:
A. selecting a base material, coating the second PVDF slurry on the lower surface of the base material at a speed of 80m/min to obtain a second PVDF coating, and placing the second PVDF coating at 60 DEG CDrying twice under the condition, and drying for 30s once to obtain a membrane A; the second PVDF coating had an areal density of 0.8g/m2；
B. Coating the first PVDF slurry on the upper surface of a base material at a speed of 80m/min to obtain a first PVDF coating, and drying the first PVDF coating at the temperature of 60 ℃ for 30s to obtain an asymmetric PVDF coated diaphragm; the areal density of the first PVDF coating was 0.5g/m2。
Example 7
(1) Preparing PVDF slurry:
A. preparing a first PVDF slurry: 5% of binder, 90% of deionized water, 0.1% of PVDF monomer and 4.9% of auxiliary agent are mixed to obtain a first PVDF slurry;
B. preparing a second PVDF slurry: 5% of binder, 75% of deionized water, 10% of PVDF monomer and 10% of auxiliary agent are mixed to obtain a second PVDF slurry;
(2) coating a separator:
A. selecting a base material, coating the second PVDF slurry on the lower surface of the base material at the speed of 80m/min to obtain a second PVDF coating, drying the second PVDF coating twice at the temperature of 60 ℃, and drying for 30s once to obtain a diaphragm A; the second PVDF coating has an areal density of 1g/m2；
B. Coating the first PVDF slurry on the upper surface of a base material at a speed of 80m/min to obtain a first PVDF coating, and drying the first PVDF coating at the temperature of 60 ℃ for 30s to obtain an asymmetric PVDF coated diaphragm; the areal density of the first PVDF coating was 0.5g/m2。
Example 8
(1) Preparing PVDF slurry:
A. preparing a first PVDF slurry: 5% of binder, 75% of deionized water, 10% of PVDF monomer and 10% of auxiliary agent are mixed to obtain a first PVDF slurry;
B. preparing a second PVDF slurry: 8% of binder, 77% of deionized water, 10% of PVDF monomer and 5% of auxiliary agent are mixed to obtain a second PVDF slurry;
(2) coating a separator:
A. selecting a base material, coating the second PVDF slurry on the lower surface of the base material at the speed of 80m/min to obtain a second PVDF coating, and drying the second PVDF coating at the temperature of 60 DEG CDrying for 30s twice and once to obtain a diaphragm A; the second PVDF coating has an areal density of 1g/m2；
B. Coating the first PVDF slurry on the upper surface of a base material at a speed of 80m/min to obtain a first PVDF coating, and drying the first PVDF coating at the temperature of 60 ℃ for 30s to obtain an asymmetric PVDF coated diaphragm; the areal density of the first PVDF coating was 0.5g/m2。
Example 9
(1) Preparing PVDF slurry:
A. preparing a first PVDF slurry: 5% of binder, 75% of deionized water, 10% of PVDF monomer and 10% of auxiliary agent are mixed to obtain a first PVDF slurry;
B. preparing a second PVDF slurry: mixing 3% of binder, 75% of deionized water, 20% of PVDF monomer and 2% of auxiliary agent to obtain second PVDF slurry;
(2) coating a separator:
A. selecting a base material, coating the second PVDF slurry on the lower surface of the base material at the speed of 80m/min to obtain a second PVDF coating, drying the second PVDF coating twice at the temperature of 60 ℃, and drying for 30s once to obtain a diaphragm A; the second PVDF coating has an areal density of 1g/m2；
B. Coating the first PVDF slurry on the upper surface of a base material at a speed of 80m/min to obtain a first PVDF coating, and drying the first PVDF coating at the temperature of 60 ℃ for 30s to obtain an asymmetric PVDF coated diaphragm; the areal density of the first PVDF coating was 0.5g/m2。
Experiment 2: taking the embodiment 3 and the embodiments 6-9 as comparative examples, contacting the second PVDF coating layer of the coated diaphragm prepared in the embodiments 3 and 6-9 with the positive pole piece of the battery, contacting the first PVDF coating layer of the coated diaphragm with the negative pole piece of the battery, and hot-pressing to obtain a wide sample strip; and then respectively taking sample bars with the width of 15mm, and testing the 180-degree peel strength of the diaphragm and the pole piece. Hot pressing temperature: 90 ℃; hot-pressing strength: 1.4 MPa; hot pressing time is 100 s; stripping speed: 50 mm/min.
The specific test results are shown in table 2:
table 2.
Figure BDA0002709246130000091
From the data in table 2, it can be seen that, according to the data in examples 3, 6 and 7, the increase in the surface density of the second PVDF coating layer can gradually reduce the difference in the adhesive force between the coated separator and the positive and negative electrode plates of the battery; it can be seen from the data in examples 8 and 9 that the difference in the ratio of the adhesive and the difference in the areal density between the second PVDF coating and the first PVDF coating can make the adhesive strength between the coated separator and the positive and negative electrode plates of the battery equal, thereby improving the uniformity of the battery, wherein the coated separator prepared in example 9 has the best effect on the uniformity of the battery.
From the above data and experiments, we can conclude that: the invention prepares an asymmetric PVDF coating diaphragm through different coating compositions and manufacturing processes; the adhesive force of the two sides of the diaphragm is different, so that the difference of the surfaces of the positive and negative pole pieces of the battery can be matched, the adhesive force of the diaphragm and the adhesive force of the positive and negative pole pieces of the battery are kept consistent, the consistency of the battery is improved, the electrical property of the battery is ensured, and the cycle life and the charge-discharge efficiency of the battery are improved.
Finally, it should be noted that: although the present invention has been described in detail with reference to the foregoing embodiments, it will be apparent to those skilled in the art that changes may be made in the embodiments and/or equivalents thereof without departing from the spirit and scope of the invention. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims (10)

1. An asymmetric PVDF-coated separator, characterized by: the coated membrane comprises a substrate and PVDF slurry; the PVDF sizing agent is respectively coated on the upper surface and the lower surface of the base material.
2. An asymmetric PVDF coated separator as in claim 1, wherein: the PVDF slurry comprises the following raw material components: 1-30% of PVDF monomer, 1-20% of adhesive, 1-15% of auxiliary agent and 60-95% of deionized water by mass fraction.
3. An asymmetric PVDF coated separator as in claim 1, wherein: the PVDF slurry also comprises a first PVDF slurry and a second PVDF slurry; the first PVDF slurry is coated on the upper surface of the base material to form a first PVDF coating; and the second PVDF slurry is coated on the lower surface of the base material to form a second PVDF coating, and the adhesive force of the second PVDF coating is greater than that of the first PVDF coating.
4. The asymmetric PVDF-coated membrane as claimed in claim 3, wherein the raw material components of the first PVDF slurry are as follows: 1-10% of PVDF monomer, 1-5% of adhesive, 0.1-10% of auxiliary agent and 75-90% of deionized water in percentage by mass.
5. The asymmetric PVDF-coated membrane as claimed in claim 4, wherein the second PVDF slurry comprises the following raw material components: 10-20% of PVDF monomer, 3-10% of adhesive, 0.1-10% of auxiliary agent and 75-86.9% of deionized water in percentage by mass.
6. An asymmetric PVDF-coated membrane as in claim 5, wherein: the mass ratio of the PVDF monomer to the adhesive in the first PVDF coating is P1, the mass ratio of the PVDF monomer to the adhesive in the second PVDF coating is P2, and the relationship between P1 and P2 satisfies the following conditions: p1 is more than or equal to 2 and more than or equal to P2 and more than or equal to 50.
7. An asymmetric PVDF coated separator as in claim 3, wherein: the first PVDF coating has an areal density of M1, and the second PVDF coating has an areal density of M2; the areal density relationship of the first PVDF coating and the second PVDF coating is as follows: 0.1g/m2≤M1＜M2≤2g/m2。
8. An asymmetric PVDF coated separator as in claim 2, wherein: the particle size of the PVDF monomer is 0.1-1 μm; the adhesive is one or more of poly (methyl) acrylic acid, poly (methyl) acrylate, polyvinyl acetate, butadiene-styrene copolymer, styrene-acrylate copolymer, ethylene-ethyl acetate copolymer, polyacrylonitrile, polyurethane and polyvinyl alcohol; the base material is one of a polyolefin diaphragm, a polyolefin composite diaphragm and a PET diaphragm.
9. A preparation method of an asymmetric PVDF coating membrane is characterized by comprising the following steps:
(1) preparing PVDF slurry:
A. preparing a first PVDF slurry;
B. preparing a second PVDF slurry;
(2) coating a separator:
A. selecting a base material, coating the second PVDF slurry on the lower surface of the base material at the speed of 20-100m/min to obtain a second PVDF coating, and drying the second PVDF coating twice at the temperature of 40-80 ℃ to obtain a diaphragm A;
B. and coating the first PVDF slurry on the upper surface of the substrate at the speed of 20-100m/min to obtain a first PVDF coating, and drying the first PVDF coating once at the temperature of 40-80 ℃ to obtain the asymmetric PVDF coated membrane.
10. The method of claim 9 for preparing an asymmetric PVDF coated separator, wherein: the drying temperature of the step A in the step (2) is T1, the drying temperature of the step B in the step (2) is T2, and the relation between T1 and T2 is as follows: t1 is more than or equal to 40 ℃ and T2 is more than or equal to 80 ℃.
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CN114006048A (en) * 2021-10-25 2022-02-01 珠海冠宇电池股份有限公司 Battery with a battery cell
CN114665218A (en) * 2022-03-01 2022-06-24 中材锂膜有限公司 Battery diaphragm, preparation method thereof and battery

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CN111244364A (en) * 2020-01-18 2020-06-05 江苏厚生新能源科技有限公司 PVDF (polyvinylidene fluoride) coated diaphragm, preparation method thereof and lithium ion battery
CN111599969A (en) * 2020-05-29 2020-08-28 东莞市溢兴新材料科技有限公司 PVDF (polyvinylidene fluoride) -coated lithium ion battery diaphragm and preparation method thereof

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CN107611314A (en) * 2016-07-12 2018-01-19 宁德新能源科技有限公司 Lithium ion battery and its coated separator
CN108695475A (en) * 2018-05-04 2018-10-23 欣旺达电子股份有限公司 Lithium ion battery separator and lithium ion battery
CN111244364A (en) * 2020-01-18 2020-06-05 江苏厚生新能源科技有限公司 PVDF (polyvinylidene fluoride) coated diaphragm, preparation method thereof and lithium ion battery
CN111599969A (en) * 2020-05-29 2020-08-28 东莞市溢兴新材料科技有限公司 PVDF (polyvinylidene fluoride) -coated lithium ion battery diaphragm and preparation method thereof

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN114006048A (en) * 2021-10-25 2022-02-01 珠海冠宇电池股份有限公司 Battery with a battery cell
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CN114665218A (en) * 2022-03-01 2022-06-24 中材锂膜有限公司 Battery diaphragm, preparation method thereof and battery

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