CN111613761A - Lithium ion battery diaphragm and preparation method and application thereof - Google Patents
Lithium ion battery diaphragm and preparation method and application thereof Download PDFInfo
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- CN111613761A CN111613761A CN202010520553.5A CN202010520553A CN111613761A CN 111613761 A CN111613761 A CN 111613761A CN 202010520553 A CN202010520553 A CN 202010520553A CN 111613761 A CN111613761 A CN 111613761A
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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
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- 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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Abstract
The invention discloses a lithium ion battery diaphragm and a preparation method and application thereof. The lithium ion battery diaphragm comprises a base material, a first composite membrane arranged on one side of the base material and a second composite membrane arranged on the other side of the base material, wherein the first composite membrane is formed by coating silane compound slurry, and the second composite membrane is formed by coating solvent type polymer slurry. The first composite membrane grafts the silane polymer with a three-dimensional network structure on the surface of the two-dimensional linear fiber structure of the substrate through a cross-linking technology, so that the membrane breaking temperature of the diaphragm is greatly improved, and the safety performance of a battery core is improved in the application of the battery; the flaky ceramic particles contained in the second composite film can greatly improve the hot needle puncture performance of the diaphragm, and the polymer coating can improve the bonding performance between the diaphragm and the pole piece and increase the hardness of the battery cell. Thus, the finished film has excellent safety properties.
Description
Technical Field
The invention relates to the technical field of lithium ion battery diaphragms, in particular to a lithium ion battery diaphragm and a preparation method and application thereof.
Background
The separator is a key element of lithium ion batteries, which prevents possible short circuits between the electrodes and facilitates ion transport. In the lithium ion battery, the separator is used not only to electrically isolate the cathode and the anode from each other, but also to play an important role in improving the stability of the battery.
The lithium ion battery is a battery which does not use metallic lithium and has high stability. However, there is a disadvantage in that various measures are required to prevent ignition of the battery, which may be caused by using various flammable materials, such as Li-LiC, electrolyte, etc., as constituent components of the battery. Polyolefin-based separators are generally used as separators for lithium ion batteries. To meet the demand for improved battery stability, composite membranes have recently been introduced as novel high-safety separators.
Although the wettability of electrolyte and the thermal stability of the lithium ion battery can be improved by adding the inorganic material in the diaphragm coating, the national requirements on the safety performance of new energy automobiles are higher and higher, and the existing traditional technology is difficult to have new breakthrough.
The current lithium ion battery has the problems of low diaphragm rupture temperature, poor temperature resistance and low passing rate in puncture test. Therefore, it is urgently needed to develop a lithium ion battery which further improves the safety performance of the diaphragm on the premise of reducing or keeping the thickness of the diaphragm unchanged.
In view of this, the invention is particularly proposed.
Disclosure of Invention
The invention aims to overcome the defects in the prior art and provide a lithium ion battery separator, and a preparation method and application thereof.
The invention is realized by the following steps:
the embodiment of the invention provides a lithium ion battery diaphragm which comprises a base material, a first composite membrane arranged on one side of the base material and a second composite membrane arranged on the other side of the base material, wherein the first composite membrane is formed by coating silane compound slurry, and the second composite membrane is formed by coating solvent type polymer slurry.
The embodiment of the invention also provides a preparation method of the lithium ion battery diaphragm, which comprises the following steps: and coating silane compound slurry on one side of the base material to form a first composite film, and coating solvent type polymer slurry on the other side of the base material to form a second composite film, so as to obtain the lithium ion battery diaphragm.
An embodiment of the present invention further provides a lithium ion battery, including: the lithium ion battery comprises a positive electrode, a negative electrode and a lithium ion battery diaphragm arranged between the positive electrode and the negative electrode, wherein the lithium ion battery diaphragm is the lithium ion battery diaphragm.
The invention has the following beneficial effects:
the invention provides a lithium ion battery diaphragm and a preparation method and application thereof. The lithium ion battery diaphragm comprises a base material, a first composite membrane arranged on one side of the base material and a second composite membrane arranged on the other side of the base material, wherein the first composite membrane is formed by coating silane compound slurry, and the second composite membrane is formed by coating solvent type polymer slurry. According to the first composite membrane on one side of the lithium ion battery diaphragm, the base material is grafted into a silane polymer with a three-dimensional network structure from a two-dimensional linear fiber structure through the crosslinking of silane compound slurry and the base material, so that the diaphragm breaking temperature of the diaphragm is greatly improved, and the safety performance of a battery core is improved in the application of the battery; the second composite film on the other side is coated with the solvent-based polymer slurry to form a polymer coating, so that the bonding performance between the diaphragm and the pole piece is improved, the hardness of the battery cell is increased, and the finished film has excellent safety performance.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. The examples, in which specific conditions are not specified, were conducted under conventional conditions or conditions recommended by the manufacturer. The reagents or instruments used are not indicated by the manufacturer, and are all conventional products available commercially.
In a first aspect, embodiments of the present invention provide a lithium ion battery separator, which includes a substrate, a first composite film disposed on one side of the substrate, and a second composite film disposed on the other side of the substrate, where the first composite film is formed by coating a silane compound slurry, and the second composite film is formed by coating a solvent-based polymer slurry.
In an optional embodiment, the silane compound slurry comprises, by mass, 0.7 to 7% of a silane coupling agent, 0.2 to 2.7% of a peroxide, 0.1 to 0.3% of a catalyst, and the balance of a solvent;
preferably, the silane coupling agent comprises at least one of vinyl silane, amino silane and methacryloxypropyl trimethoxy silane;
preferably, the peroxide comprises at least one of a hydroperoxide, a dialkyl peroxide, and a diphthaloperoxide;
preferably, the catalyst is a copper catalyst;
preferably, the solvent comprises at least one of ethanol, propanol, and isopropanol;
more preferably, the solid content in the silane compound paste is 1 to 10%, and again preferably 2 to 4%.
According to the lithium ion battery provided by the embodiment of the invention, the first composite membrane is formed by coating silane compound slurry, wherein the silane compound slurry contains, by mass, 0.7-7% of a silane compound, 0.2-2.7% of peroxide, 0.1-0.3% of a catalyst, and the balance of a solvent. The silane compound slurry provided by the embodiment of the invention is an organic solvent, does not contain water, and is characterized in that: in the embodiment of the invention, only the silane coupling agent is grafted to the surface of the substrate, and the terminal group of the silane coupling agent is not hydrolyzed to generate the silicon hydroxyl, specifically:
the peroxide has the following effects: at least by thermal decomposition, a radical is generated to initiate a grafting reaction of the silane coupling agent on the substrate (polymer). In particular, in the case where the silane coupling agent contains an ethylenically unsaturated group, the following effects are exhibited: the grafting reaction based on the radical reaction of the ethylenically unsaturated group with the substrate is initiated, and thus it is sufficient that the peroxide used in the embodiment of the present invention generates a radical, without particular limitation.
The silane coupling agent may have a group capable of undergoing a grafting reaction with the surface of the substrate (polymer) in the presence of a radical, and preferably has an amino group, a glycidyl group or an ethylenically unsaturated group at the terminal, and more preferably has an ethylenically unsaturated group at the terminal. Examples of the group containing an ethylenically unsaturated group include, but are not particularly limited to, vinyl, allyl, (meth) acryloyloxy, (meth) acryloyloxyalkyl, and p-styryl. These silane coupling agents may be used in combination with silane coupling agents having other terminal groups.
The catalyst has the function of promoting the condensation reaction between the grafted silane coupling agent and the surface of the base material. Based on the action of the condensation catalyst, silane coupling agent molecules can be grafted on the surface of the base material, the surface of the base material is grafted into a three-dimensional network structure from a two-dimensional linear fiber structure after crosslinking treatment, and the film rupture temperature (135 ℃ → 185 ℃) of the diaphragm is greatly increased.
In an optional embodiment, the solvent-based polymer slurry comprises, by mass, 5-18% of a polymer, 12-30% of a filler, and the balance of a solvent;
preferably, the polymer comprises at least one of polyvinylidene fluoride, polymethyl methacrylate and polyacrylonitrile;
preferably, the filler is plate-like ceramic particles comprising at least one of plate-like alumina, plate-like magnesium hydroxide and plate-like boehmite, more preferably, the plate-like ceramic particles have a transverse length of 1 to 10 μm, and more preferably, 3 to 6 μm;
preferably, the solvent comprises at least one of acetone, N-methylpyrrolidone, and dimethylacetamide;
more preferably, the solids content of the solvent-borne polymer slurry is from 20 to 40%, again preferably from 25 to 30%.
According to the lithium ion battery provided by the embodiment of the invention, the second composite film is formed by coating the solvent-based polymer slurry, wherein the solvent-based polymer slurry contains 5-18% of polymer, 12-30% of filler and the balance of solvent according to mass percentage. Experiments prove that when the filler is flaky ceramic particles, the formed polymer coating can greatly improve the hot needle puncture performance of the diaphragm, in the preferred mode provided by the embodiment of the invention, the transverse length of the flaky ceramic particles is controlled to be 1-10 mu m, and the transverse length is preferably 3-6 mu m again, because the particle size of the flaky nano ceramic particles can influence the hot needle puncture effect, the requirement on coating is higher due to too large particle size, the uniformity of the coating is difficult to control, the particle size is too small, and the puncture resistance effect is reduced; and when the polymer in the solvent-based polymer slurry is coated with the formed polymer coating, the adhesive property between the diaphragm and the pole piece can be improved, and the hardness of the battery cell is increased. Thus, the finished film has excellent safety properties.
In alternative embodiments, the substrate comprises one or more of polypropylene, polyethylene, polymethylpentene;
preferably, the thickness of the first composite film on the substrate side is 0.1 to 4 μm, more preferably 0.5 to 4 μm;
preferably, the thickness of the second composite film on the other side of the substrate is 1 to 6 μm, more preferably 2 to 4 μm.
If the thickness of the first composite membrane is too high, the solution is remained on the surface of the membrane, the air permeability ion conductivity of the membrane is influenced, and if the thickness is too low, the problem that the membrane breaking temperature and the strength of the membrane are reduced due to insufficient crosslinking reaction can occur; if the thickness of the second composite film is too high, the two materials are insufficiently separated, the coating is easy to fall off, the air permeability is high, the impedance is high, the adhesion and the temperature resistance are poor, and the safety is reduced due to too low thickness.
In a second aspect, an embodiment of the present invention provides a preparation method of the above lithium ion battery separator, including the following steps: and coating silane compound slurry on one side of the base material to form a first composite film, and coating solvent type polymer slurry on the other side of the base material to form a second composite film, so as to obtain the lithium ion battery diaphragm.
In an alternative embodiment, the preparation of the first composite membrane comprises the steps of:
coating the silane compound slurry on one side of a base material through a micro-gravure, and controlling the temperature to be raised from 55 ℃ to 65 ℃ and then reduced to 60 ℃ during coating to obtain a first composite film;
preferably, the silane compound slurry is prepared by mixing 0.7-7% of silane coupling agent, 0.2-2.7% of peroxide, 0.1-0.3% of catalyst and the balance of solvent in proportion;
more preferably, the silane compound paste is prepared by the following steps:
mixing 0.7-7% of silane coupling agent, 0.2-2.7% of peroxide, 0.1-0.3% of catalyst and the balance of solvent, and stirring for 60-90min to obtain the silane compound slurry.
The coating mode of the first composite membrane is preferably micro-gravure coating, compared with slow dip coating, the coating mode can quickly, efficiently and uniformly spread the slurry on the surface of the diaphragm, and plays a main role in the crosslinking reaction rate and the crosslinking uniformity of subsequent crosslinking.
In an alternative embodiment, the preparation of the second composite film comprises the steps of:
coating the other side of the substrate with the solvent-based polymer slurry, controlling the temperature to rise from 60 ℃ to 70 ℃ during coating, and then reducing the temperature to 60 ℃ to obtain a second composite film;
preferably, the solvent-based polymer slurry is prepared by mixing 5-18% of polymer, 12-30% of filler and the balance of solvent in proportion;
more preferably, the solvent-borne polymer slurry is prepared by the following steps:
dissolving 5-18% of polymer in a solvent, and stirring for 30-60min to obtain a mixture;
then mixing 12-30% of the filler with the mixture, and dispersing for 30-60min to obtain a dispersion liquid;
and stirring the dispersion liquid for 5-20min, and filtering by using a filter screen with the mesh size of more than or equal to 250 to obtain the solvent-based polymer slurry.
In the preparation process of the second composite membrane, the solvent-based polymer slurry adopts step-by-step pulping, and the advantages are that: the time is controlled in each step, so that the slurry can be dispersed more uniformly, the condition that raw materials are agglomerated mutually is avoided, the yield of finished slurry is improved, and preferably, the solvent-based polymer slurry is coated in a dip coating mode.
In an alternative embodiment, the method further comprises a post-treatment, wherein the post-treatment comprises the following steps:
and (2) placing the base material coated with the first composite membrane and the second composite membrane for 12-24 hours at the temperature of 80-90 ℃ to enable the first composite membrane and the base material to generate a crosslinking reaction, and then placing the base material for 12-24 hours at the temperature of 20-30 ℃ and the humidity of 90-100% to enable the second composite membrane to generate phase separation, thereby finally preparing the lithium ion battery diaphragm.
The embodiment of the invention provides a preparation method of a lithium ion battery diaphragm, which further comprises post-treatment, wherein the first composite film and a base material can generate a cross-linking reaction through the post-treatment, and the second composite film is subjected to phase separation, specifically:
the principle of the cross-linking reaction between the first composite film and the substrate is as follows: after the coating substance in the first composite membrane is treated under the conditions of vacuum, 80-90 ℃ and 12-24h, the silane compound in the slurry can generate a crosslinking reaction with the base material under the action of the catalyst, and the silane crosslinking method comprises the following steps: under the action of catalyst and in the presence of free radical produced by peroxide making silane coupling agent with unsaturated group produce graft reaction with base material (polymer) so as to obtain the structure of base material surface grafted silane graft polymer. Namely, silane polymer with a net structure can be grafted on a linear structure of a base material through silane crosslinking, so that the temperature resistance and the film breaking temperature of the diaphragm are greatly improved.
The principle of the phase separation of the second composite membrane is as follows: after the second composite film is dip-coated in a solvent, the polymer layer and the ceramic layer can be separated by using water vapor treatment (the polymer layer is on the surface layer, and the ceramic layer is on the inner layer), so that the adhesion, the temperature resistance and the puncture resistance of the diaphragm are improved. Preferably, the substrate coated with the composite film provided by the embodiment of the invention is placed for 12-24 hours under the conditions that the temperature is 20-30 ℃ and the humidity is 90-100%, so that two substances which are not completely separated in the second composite film can be further separated, the second composite film can better form holes under the humidity, the air permeability value of the crosslinked diaphragm is reduced, the adhesion is enhanced, and the thermal shrinkage is improved.
In an optional embodiment, the preparation method of the lithium ion battery separator comprises the following specific steps:
mixing 0.7-7% of silane coupling agent, 0.2-2.7% of peroxide, 0.1-0.3% of catalyst and the balance of solvent, and stirring for 60-90min to obtain silane compound slurry; coating the silane compound slurry on one side of a base material through a micro-gravure, controlling the temperature to rise from 55 ℃ to 65 ℃ during coating, then reducing the temperature to 60 ℃, drying and standing to obtain the base material coated with the first composite film;
dissolving 5-18% of polymer in a solvent, stirring for 30-60min to obtain a mixture, then mixing 12-30% of filler with the mixture, dispersing for 30-60min to obtain a dispersion, stirring for 5-20min, and filtering with a filter screen of more than or equal to 250 meshes to obtain solvent-based polymer slurry; coating the other side of the substrate with the solvent-based polymer slurry, controlling the temperature to rise from 60 ℃ to 70 ℃ during coating, then reducing the temperature to 60 ℃, drying and standing to obtain the substrate coated with the first composite film and the second composite film;
and (2) placing the base material coated with the first composite membrane and the second composite membrane for 12-24 hours at the temperature of 80-90 ℃ to enable the first composite membrane and the base material to generate a crosslinking reaction, and then placing the base material for 12-24 hours at the temperature of 20-30 ℃ and the humidity of 90-100% to enable the second composite membrane to generate phase separation, thereby finally preparing the lithium ion battery diaphragm.
In a third aspect, an embodiment of the present invention further provides a lithium ion battery, including: the lithium ion battery comprises a positive electrode, a negative electrode and a lithium ion battery diaphragm arranged between the positive electrode and the negative electrode, wherein the lithium ion battery diaphragm is the lithium ion battery diaphragm.
The features and properties of the present invention are described in further detail below with reference to examples.
Example 1
A preparation method of a lithium ion battery diaphragm comprises the following specific steps:
mixing 0.7% of vinyl silane, 0.2% of chlorine peroxide, 0.1% of copper catalyst and 99% of ethanol according to mass percent, and stirring for 70min to obtain silane compound slurry with the viscosity of 5 cp; coating the silane compound slurry on one side of a base material through a micro-gravure, controlling the temperature gradient to be 55-65-60 ℃ during coating, drying and standing to obtain the base material of a first composite film with the thickness of 0.1 mu m;
dissolving 10% of polyvinylidene fluoride (PVDF) in 60% of acetone according to mass percentage, stirring for 30min to obtain a mixture, then mixing 30% of flaky ceramic particles with the particle size of 10 mu m with the mixture, dispersing for 30min to obtain a dispersion liquid, stirring the dispersion liquid for 10min, and filtering by using a filter screen with the mesh size of more than or equal to 250 to obtain solvent-based polymer slurry with the viscosity of 5 cp; coating the solvent-based polymer slurry on the other side of the substrate, wherein the temperature gradient of an oven is 60-70-60 ℃ during coating, and drying and standing to obtain the substrate of a first composite film with the thickness of 0.1 mu m and a second composite film with the thickness of 1 mu m;
and (3) placing the base material coated with the first composite membrane and the second composite membrane for 12 hours at the temperature of 80 ℃ to enable the first composite membrane and the base material to generate a crosslinking reaction, then placing the base material for 12 hours at the temperature of 20 ℃ and the humidity of 90% to enable the second composite membrane to generate phase separation, and finally preparing the lithium ion battery diaphragm.
The following table 1 shows the compositions and properties of the silane compound pastes in examples 2 to 5 of the present invention, and table 2 shows the compositions and properties of the solvent-based polymer pastes in examples 2 to 5 of the present invention.
TABLE 1 composition and Properties of the first composite film
TABLE 2 composition and Properties of the second composite film
Table 3 below shows properties of the lithium ion battery separator in comparative examples 1 to 3, in which both sides of the substrate in comparative example 1 are the first composite film, both sides of the substrate in comparative example 2 are the second composite film, and the aqueous ceramic PVDF composite separator in comparative example 3.
TABLE 3 comparative examples
Table 4 below shows the performance of the separators of examples 1 to 5 of the present invention compared with those of comparative examples 1 to 3.
Table 4 comparison of the properties of the separators in examples 1 to 5 with those in comparative examples 1 to 3
As can be seen from table 4 above:
(1) compared with the embodiment, after the diaphragm is subjected to cross-linking treatment, the diaphragm rupture temperature of the diaphragm is gradually increased along with the increase of the addition amount of the vinyl silane, the thermal shrinkage is gradually reduced, and the temperature resistance of the diaphragm can be effectively improved;
(2) along with the increase of the addition amount of the vinyl silane, the ventilation value of the diaphragm is gradually increased, and the conduction of lithium ions is not facilitated;
(3) and the puncture diameter of the hot needle is obviously reduced through the diaphragm after phase separation treatment, which shows that the flaky ceramic particles can effectively prevent the diffusion of heat, thereby further improving the safety of the diaphragm.
Compared with the prior art, the embodiment of the invention has the following beneficial effects:
(1) the first composite membrane on one side of the base material in the lithium ion battery diaphragm enables the base material to be grafted into a three-dimensional network structure from a two-dimensional linear fiber structure through a cross-linking technology, so that the diaphragm breaking temperature of the diaphragm is greatly improved, and the safety performance of a battery core is improved in the application of the battery;
(2) the second composite membrane is arranged on the other side of the substrate in the lithium ion battery diaphragm, the flaky ceramic particles contained in the second composite membrane can greatly improve the hot needle puncture performance of the diaphragm, and the polymer coating can improve the bonding performance between the diaphragm and the pole piece and increase the hardness of the battery core. Thus, the finished film has excellent safety properties.
The above is only a preferred embodiment of the present invention, and is not intended to limit the present invention, and various modifications and changes will occur to those skilled in the art. 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. The lithium ion battery diaphragm is characterized by comprising a base material, a first composite film and a second composite film, wherein the first composite film is arranged on one side of the base material, the second composite film is arranged on the other side of the base material, the first composite film is formed by coating silane compound slurry, and the second composite film is formed by coating solvent type polymer slurry.
2. The lithium ion battery separator according to claim 1, wherein the silane compound slurry comprises, in mass percent, 0.7 to 7% of a silane coupling agent, 0.2 to 2.7% of a peroxide, 0.1 to 0.3% of a catalyst, and the balance being a solvent;
preferably, the silane coupling agent comprises at least one of vinyl silane, amino silane and methacryloxypropyl trimethoxy silane;
preferably, the peroxide comprises at least one of a hydroperoxide, a dialkyl peroxide, and a diphthaloperoxide;
preferably, the catalyst is a copper catalyst;
preferably, the solvent comprises at least one of ethanol, propanol and isopropanol;
more preferably, the solid content in the silane compound paste is 1 to 10%, and again preferably 2 to 4%.
3. The lithium ion battery separator according to claim 1, wherein the solvent-based polymer slurry comprises, in mass percent, 5-18% of a polymer, 12-30% of a filler, and the balance of a solvent;
preferably, the polymer comprises at least one of polyvinylidene fluoride, polymethyl methacrylate and polyacrylonitrile;
preferably, the filler is a plate-like ceramic particle comprising at least one of plate-like alumina, plate-like magnesium hydroxide and plate-like boehmite, more preferably, the plate-like ceramic particle has a transverse length of 1 to 10 μm, and more preferably, 3 to 6 μm;
preferably, the solvent comprises at least one of acetone, N-methylpyrrolidone, and dimethylacetamide;
more preferably, the solids content of the solventborne polymer syrup is from 20 to 40%, again preferably from 25 to 30%.
4. The lithium ion battery separator according to claim 1, wherein the substrate comprises one or more of polypropylene, polyethylene and polymethylpentene;
preferably, the thickness of the first composite film on the substrate side is 0.1 to 4 μm, more preferably 0.5 to 4 μm;
preferably, the thickness of the second composite film on the other side of the substrate is 1 to 6 μm, more preferably 2 to 4 μm.
5. A preparation method of the lithium ion battery separator according to any one of claims 1 to 4, characterized by comprising the following steps: and coating the silane compound slurry on one side of the substrate to form a first composite film, and then coating the solvent-based polymer slurry on the other side of the substrate to form a second composite film.
6. The preparation method of the lithium ion battery separator according to claim 5, wherein the preparation of the first composite membrane comprises the following steps:
coating the silane compound slurry on one side of the base material through a micro-gravure, and controlling the temperature to be raised from 55 ℃ to 65 ℃ and then lowered to 60 ℃ during coating to obtain a first composite film;
preferably, the silane compound slurry is prepared by mixing 0.7-7% of silane coupling agent, 0.2-2.7% of peroxide, 0.1-0.3% of 20 catalyst and the balance of solvent in proportion;
more preferably, the silane compound slurry is prepared by the following steps:
mixing 0.7-7% of silane coupling agent, 0.2-2.7% of peroxide, 0.1-0.3% of catalyst and the balance of solvent, and stirring for 60-90min to obtain the silane compound slurry.
7. The preparation method of the lithium ion battery separator according to claim 5, wherein the preparation of the second composite membrane comprises the following steps:
coating the other side of the substrate with the solvent-based polymer slurry, and controlling the temperature to rise from 60 ℃ to 70 ℃ and then reduce to 60 ℃ during coating to obtain a second composite film;
preferably, the solvent-based polymer slurry is prepared by mixing 5-18% of polymer, 12-30% of filler and the balance of solvent in proportion;
more preferably, the solvent-borne polymer slurry is prepared by the following steps:
dissolving 5-18% of polymer in a solvent, and stirring for 30-60min to obtain a mixture;
then mixing 12-30% of filler with the mixture, and dispersing for 30-60min to obtain dispersion liquid;
and stirring the dispersion liquid for 5-20min, and filtering by using a filter screen with the mesh size of more than or equal to 250 to obtain the solvent-based polymer slurry.
8. The method for preparing the lithium ion battery separator according to claim 5, further comprising a post-treatment, wherein the post-treatment comprises the following steps:
and (2) placing the base material coated with the first composite membrane and the second composite membrane for 12-24 hours at the temperature of 80-90 ℃ to enable the first composite membrane and the base material to generate a crosslinking reaction, then placing the base material for 12-24 hours at the temperature of 20-30 ℃ and the humidity of 90-100% to enable the second composite membrane to generate phase separation, and finally preparing the lithium ion battery diaphragm.
9. The method for preparing the lithium ion battery separator according to any one of claims 5 to 8, comprising the steps of:
mixing 0.7-7% of silane coupling agent, 0.2-2.7% of peroxide, 0.1-0.3% of catalyst and the balance of solvent, and stirring for 60-90min to obtain silane compound slurry; coating the silane compound slurry on one side of the base material through a micro-gravure, controlling the temperature to rise from 55 ℃ to 65 ℃ during coating, then reducing the temperature to 60 ℃, drying and standing to obtain the base material coated with the first composite film;
dissolving 5-18% of polymer in a solvent, stirring for 30-60min to obtain a mixture, then mixing 12-30% of filler with the mixture, dispersing for 30-60min to obtain a dispersion, stirring the dispersion for 5-20min, and filtering with a filter screen of more than or equal to 250 meshes to obtain solvent-based polymer slurry; coating the other side of the substrate with the solvent-based polymer slurry, controlling the temperature to rise from 60 ℃ to 70 ℃ during coating, then reducing the temperature to 60 ℃, drying and standing to obtain the substrate coated with the first composite film and the second composite film;
and (2) placing the base material coated with the first composite membrane and the second composite membrane for 12-24 hours at the temperature of 80-90 ℃ to enable the first composite membrane and the base material to generate a crosslinking reaction, then placing the base material for 12-24 hours at the temperature of 20-30 ℃ and the humidity of 90-100% to enable the second composite membrane to generate phase separation, and finally preparing the lithium ion battery diaphragm.
10. A lithium ion battery, comprising: the lithium ion battery diaphragm is prepared by the lithium ion battery diaphragm according to any one of claims 1 to 4 or the preparation method according to any one of claims 5 to 9.
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN112216930A (en) * | 2020-10-29 | 2021-01-12 | 中材锂膜有限公司 | High-air-permeability high-temperature-resistant diaphragm of lithium battery and preparation method of high-air-permeability high-temperature-resistant diaphragm |
| CN115295964A (en) * | 2022-09-02 | 2022-11-04 | 上海恩捷新材料科技有限公司 | Lithium ion battery coating diaphragm |
| CN115498365A (en) * | 2022-08-18 | 2022-12-20 | 江西省通瑞新能源科技发展有限公司 | High-heat-resistance diaphragm and preparation method and application thereof |
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| CN110326128A (en) * | 2018-01-31 | 2019-10-11 | 株式会社Lg化学 | Diaphragm includes the lithium secondary battery of diaphragm and its manufacturing method |
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| CN103236511A (en) * | 2013-04-18 | 2013-08-07 | 广东工业大学 | Preparation method of super-heat-resistant organic/inorganic composite film |
| CN110326128A (en) * | 2018-01-31 | 2019-10-11 | 株式会社Lg化学 | Diaphragm includes the lithium secondary battery of diaphragm and its manufacturing method |
| CN108963164A (en) * | 2018-06-28 | 2018-12-07 | 深圳市旭然电子有限公司 | Inorganic ceramic coating functions lithium ion battery isolation film, preparation method and its lithium ion battery |
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| CN112216930A (en) * | 2020-10-29 | 2021-01-12 | 中材锂膜有限公司 | High-air-permeability high-temperature-resistant diaphragm of lithium battery and preparation method of high-air-permeability high-temperature-resistant diaphragm |
| CN115498365A (en) * | 2022-08-18 | 2022-12-20 | 江西省通瑞新能源科技发展有限公司 | High-heat-resistance diaphragm and preparation method and application thereof |
| CN115295964A (en) * | 2022-09-02 | 2022-11-04 | 上海恩捷新材料科技有限公司 | Lithium ion battery coating diaphragm |
| CN115295964B (en) * | 2022-09-02 | 2023-06-23 | 上海恩捷新材料科技有限公司 | Lithium ion battery coating diaphragm |
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