CN117410650A - Battery separator and secondary battery - Google Patents

Battery separator and secondary battery Download PDF

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Publication number
CN117410650A
CN117410650A CN202311717486.6A CN202311717486A CN117410650A CN 117410650 A CN117410650 A CN 117410650A CN 202311717486 A CN202311717486 A CN 202311717486A CN 117410650 A CN117410650 A CN 117410650A
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China
Prior art keywords
microcapsule
self
battery separator
core layer
battery
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Pending
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CN202311717486.6A
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Chinese (zh)
Inventor
李昭
熊德兰
刘建金
吴晓丹
周南杰
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Shenzhen Zhongxing New Material Technology Co ltd
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Shenzhen Zhongxing New Material Technology Co ltd
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Priority to CN202311717486.6A priority Critical patent/CN117410650A/en
Publication of CN117410650A publication Critical patent/CN117410650A/en
Pending legal-status Critical Current

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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
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
    • H01M50/409—Separators, membranes or diaphragms characterised by the material
    • H01M50/449—Separators, membranes or diaphragms characterised by the material having a layered structure
    • 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
    • H01M10/42—Methods or arrangements for servicing or maintenance of secondary cells or secondary half-cells
    • H01M10/4235—Safety or regulating additives or arrangements in electrodes, separators or electrolyte
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
    • H01M50/489—Separators, membranes, diaphragms or spacing elements inside the cells, characterised by their physical properties, e.g. swelling degree, hydrophilicity or shut down properties
    • 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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  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Electrochemistry (AREA)
  • General Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Manufacturing & Machinery (AREA)
  • Cell Separators (AREA)

Abstract

The invention provides a battery diaphragm and a secondary battery, wherein the battery diaphragm comprises a base material and a self-repairing coating; the self-repairing coating is arranged on at least one side surface of the substrate; the self-repairing coating comprises a first microcapsule and a second microcapsule, wherein the first microcapsule is provided with a first shell layer and a first core layer, the first core layer is coated on the inner side of the first shell layer, and the first core layer comprises a free radical polymerization monomer; and the second microcapsule is provided with a second shell layer and a second core layer, the second core layer is coated on the inner side of the second shell layer, and the second core layer comprises a catalyst and/or a cross-linking agent for initiating cross-linking of the free radical polymerization monomer. According to the self-repairing coating, the self-repairing coating is arranged on the surface of the base material, when the battery diaphragm is damaged, the first microcapsule and the second microcapsule release free radical polymerization monomers, and the catalyst and/or the cross-linking agent, and the substances can flow to the damaged interface on the battery diaphragm after being released, so that the self-repairing function is carried out on the battery diaphragm, and the improvement of the puncture resistance is realized.

Description

Battery separator and secondary battery
Technical Field
The invention relates to the field of secondary batteries, in particular to a battery diaphragm and a secondary battery.
Background
The battery diaphragm is an important component for forming the battery core of the secondary battery, and is a film for separating the positive electrode from the negative electrode and preventing direct reaction from losing energy when in electrolytic reaction. The performance of the battery diaphragm determines the interface structure, internal resistance and the like of the battery, directly influences the capacity, circulation, safety performance and other characteristics of the battery, and the battery diaphragm with excellent performance plays an important role in improving the comprehensive performance of the battery.
In recent years, in order to increase the energy density and the power density of a battery, the battery is increasingly lighter, and the thickness of a separator is reduced in the future. However, weight reduction brings about deterioration in mechanical properties of the separator, which is a measure of durability during battery fabrication and battery cycling of the polyolefin separator.
The puncture resistance strength is an important performance index of the battery diaphragm, and the low puncture resistance strength easily causes the problems of short circuit, explosion and the like of the battery in the aging process of the battery. The above problems are technical problems to be solved in the art.
Disclosure of Invention
The invention mainly solves the technical problem of providing a battery diaphragm and a secondary battery capable of effectively improving puncture resistance strength of the secondary battery.
According to a first aspect, the present application provides a battery separator comprising: a substrate; and
a self-healing coating layer disposed on at least one side surface of the substrate; the self-healing coating includes a first microcapsule and a second microcapsule,
the first microcapsule is provided with a first shell layer and a first core layer, the first core layer is coated on the inner side of the first shell layer, and the first core layer comprises a free radical polymerization monomer;
the second microcapsule has a second shell layer and a second core layer, the second core layer is coated on the inner side of the second shell layer, and the second core layer contains a catalyst and/or a cross-linking agent for initiating the cross-linking of the free radical polymerization monomer.
In an alternative embodiment, the thickness of the self-healing coating is 10% -40% of the total thickness of the battery separator.
In an alternative embodiment, the self-healing coating satisfies at least one of conditions (1) to (3):
(1) The particle size of the first microcapsule and/or the second microcapsule is 0.5-10 μm;
(2) The mass ratio of the first microcapsule to the second microcapsule is 1:1;
(3) The thickness of the self-repairing coating is 0.5-6 mu m.
In an alternative embodiment, the free radical polymerizable monomers include dicyclopentadiene, polydiethoxysiloxane, terminal hydroxylated polydimethylsiloxane, and the like.
In an alternative embodiment, the second core layer includes at least one of a granny catalyst, di-n-butyltin dilaurate, a tungsten hexachloride phenylacetylene mixture, and an azide.
In an alternative embodiment, the first shell layer comprises at least one of urea formaldehyde resin, epoxy resin, ceramic precursor resin, lecithin, fatty acid perhydro polysilazane, silica cyclodextrin, chitosan, sodium tripolyphosphate, polyurethane, polyethylene glycol, polyamide, and polyethylene.
In an alternative embodiment, the second shell layer comprises at least one of urea formaldehyde resin, epoxy resin, ceramic precursor resin, lecithin, fatty acid perhydro polysilazane, silica cyclodextrin, chitosan, sodium tripolyphosphate, polyurethane, polyethylene glycol, polyamide, and polyethylene.
In an alternative embodiment, the self-healing coating further comprises one or more of a wetting agent, a dispersing agent, and a binder.
In an alternative embodiment, the substrate satisfies at least one of conditions (1) to (3):
(1) The aperture of the base material is 20nm-100nm;
(2) The porosity of the base material is 20% -70%;
(3) The substrate comprises at least one of polyolefin, polyimide, polyvinylidene fluoride, polyamide and cellulose.
According to a second aspect, the present application provides a secondary battery comprising the battery separator described above.
The beneficial effects of this application lie in: according to the self-repairing coating, the self-repairing coating comprises the first microcapsule and the second microcapsule, when the battery diaphragm is rubbed and punctured by foreign matters, the first microcapsule and the second microcapsule release free radical polymerization monomers, and the catalyst and/or the cross-linking agent capable of promoting the cross-linking reaction to occur, and the substances flow to the damaged interface on the battery diaphragm after being released, so that the free radical polymerization monomers are subjected to the cross-linking reaction at the damaged interface, the self-repairing function is carried out on the battery diaphragm, the improvement of the puncture resistance is realized, and the occurrence of short circuits is prevented.
Drawings
FIG. 1 is a schematic view of a layered structure in one embodiment of the present application;
FIG. 2 is a schematic view of a layered structure according to another embodiment of the present application;
FIG. 3 is a schematic structural view of a first microcapsule or a second microcapsule in an embodiment of the present disclosure;
fig. 4 is an SEM image of a self-healing coating in one embodiment of the present application.
Reference numerals: a substrate 1, a self-healing coating 2, a first core layer 31a, a first shell layer 31b, a second core layer 32a, and a second shell layer 32b.
Detailed Description
The invention will be described in further detail below with reference to the drawings by means of specific embodiments. Wherein like elements in different embodiments are numbered alike in association. In the following embodiments, numerous specific details are set forth in order to provide a better understanding of the present application. However, one skilled in the art will readily recognize that some of the features may be omitted, or replaced by other elements, materials, or methods in different situations. In some instances, some operations associated with the present application have not been shown or described in the specification to avoid obscuring the core portions of the present application, and may not be necessary for a person skilled in the art to describe in detail the relevant operations based on the description herein and the general knowledge of one skilled in the art.
Furthermore, the described features, operations, or characteristics of the description may be combined in any suitable manner in various embodiments. Also, various steps or acts in the method descriptions may be interchanged or modified in a manner apparent to those of ordinary skill in the art. Thus, the various orders in the description and drawings are for clarity of description of only certain embodiments, and are not meant to be required orders unless otherwise indicated.
The numbering of the components itself, e.g. "first", "second", etc., is used herein merely to distinguish between the described objects and does not have any sequential or technical meaning. The terms "coupled" and "connected," as used herein, are intended to encompass both direct and indirect coupling (coupling), unless otherwise indicated.
In the present application, the term "secondary battery" refers to a battery that can be continuously used by activating an active material by charging after discharging the battery. Such cells typically utilize the reversibility of chemical reactions, i.e., after one chemical reaction is converted to electrical energy, the chemical system can also be repaired with electrical energy and then converted to electrical energy by the chemical reaction. Among them, more common secondary batteries include, but are not limited to, nickel-hydrogen batteries, nickel-cadmium batteries, lead-acid (or lead-storage) batteries, lithium ion batteries, polymer lithium ion batteries, sodium ion batteries, and the like.
In the present application, the term "battery separator" is an important component constituting an electric core of a secondary battery, and the battery separator is a thin film for separating positive and negative electrodes to prevent direct reaction from losing energy in the case of electrolytic reaction. The performance of the battery diaphragm determines the interface structure, internal resistance and the like of the battery, directly influences the capacity, circulation, safety performance and other characteristics of the battery, and the battery diaphragm with excellent performance plays an important role in improving the comprehensive performance of the battery.
The mechanical properties of the battery separator can determine to a large extent the durability and safety during battery cycling. One way to increase the mechanical strength of a battery separator is by improving the strength of the battery separator in the MD and TD directions to impart a stronger tear resistance to the battery separator; but this approach has limited improvement in resistance to puncture.
Another way to increase the mechanical strength of the battery separator is to increase the degree of crosslinking of the polymer as substrate 1. However, current methods of establishing cross-links in polymers, one approach is to use copolymers in which one of the monomer components incorporates a ligatable segment or a monomer having two functional groups, potentially yielding linear prepolymers that can be thermally or photochemically cured. However, this strategy is not applicable when it is desired to crosslink polymeric materials lacking functional groups, such as polyolefins. Thus, one method for producing crosslinked polyethylene is to initiate crosslinking by hydrogen abstraction based on a high energy free radical process, but such methods are ineffective for polypropylene because the polypropylene has a C-C bond energy (350 kJ/mol) less than C-H (390-400 kJ/mol).
In this application, the following abbreviations of technical terms appear to be those known and clearly understood in the art, which abbreviations do not pose any obstacle to the understanding of the application by those skilled in the art, wherein:
MD, i.e. the machine direction; TD, i.e. the direction perpendicular to MD; SEM, scanning electron microscope.
The application discloses battery separator, it includes: a substrate 1 and a self-healing coating 2.
Wherein the self-healing coating 2 is arranged on at least one side of the substrate 1. For example, the self-healing coating 2 may be disposed on one side surface (see fig. 1) or the opposite side surfaces (see fig. 2) of the substrate 1 by spin coating, spray coating, roll coating, screen printing, or the like, which is not particularly limited herein.
In the embodiment disclosed in the present application, the self-repairing coating 2 is mainly composed of a first microcapsule and a second microcapsule, and the first microcapsule and the second microcapsule are both core-shell structures. Specifically, referring to fig. 3, the first microcapsule has a first shell layer 31b and a first core layer 31a, and the second microcapsule has a second shell layer 32b and a second core layer 32a; in the first microcapsule, a first shell layer 31b is coated on the outside of a first core layer 31a, thereby constituting a "container" for accommodating the first core layer 31a, the first shell layer 31b isolating the first core layer 31a from the outside; similarly, the second shell layer 32b is wrapped around the second core layer 32a, so as to isolate the second core layer 32a from the outside.
Wherein the first core layer 31a contains a radical polymerizable monomer; the second core layer 32a contains a catalyst and/or crosslinking agent for initiating crosslinking of the free radical polymerized monomer.
The working principle of the application is as follows: according to the self-repairing coating, the self-repairing coating 2 is arranged on the surface of the base material 1, and the self-repairing coating 2 comprises the first microcapsule and the second microcapsule, so that the first microcapsule and the second microcapsule are damaged in the process of being rubbed and punctured by foreign matters, the first microcapsule can release free radical polymerization monomers, the second microcapsule can release catalysts and/or crosslinking agents for promoting the crosslinking reaction to occur, and the substances can flow to the damaged interface on the battery diaphragm after being released, so that the free radical polymerization monomers can crosslink at the damaged interface to perform the self-repairing function on the battery diaphragm, so that the puncture resistance can be indirectly improved, and the occurrence of short circuits can be prevented.
The mode that adopts through repairing the battery diaphragm of this application initiative improves battery diaphragm's puncture resistance intensity, has greatly improved battery diaphragm's security and durability.
The first core layer 31a may be at least one of dicyclopentadiene, polydiethoxysilane, and hydroxyl-terminated polydimethylsiloxane. The second core layer 32a may be one or more of a granny catalyst, di-n-butyltin dilaurate, a tungsten hexachloride phenylacetylene mixture, and an azide (e.g., tris (ethylene glycol) diazirine formate, a bisaziridine group compound).
It should be understood that the first shell layer 31b and the second shell layer 32b may be the same or different, and the present application is not limited thereto, and for example, the first shell layer 31b and the second shell layer 32b may be independently selected from one or more of urea formaldehyde resin, epoxy resin, ceramic precursor resin, lecithin, fatty acid perhydro polysilazane, silica cyclodextrin, chitosan, sodium tripolyphosphate, polyurethane, polyethylene glycol, polyamide, and polyethylene, respectively.
In some alternative embodiments, the thickness of the self-healing coating 2 is 10% -40% of the total thickness of the battery separator. When the battery diaphragm is damaged, the thicker the self-repairing coating 2 is, the shorter the repairing time of the diaphragm is, the better the repairing effect is, but as the self-repairing coating 2 is thickened, the initial ventilation value of the diaphragm is influenced, the self-repairing coating 2 is controlled under the thickness proportion, the initial ventilation value of the battery diaphragm is not influenced, and the battery diaphragm can be rapidly repaired when damaged, and the self-repairing coating 2 can be 10%, 20%, 30% or 40% in an exemplary way.
In an alternative embodiment, the first microcapsules and/or the second microcapsules have a particle size of 0.5 μm to 10 μm. The present application employs first and second microcapsules having suitable particle sizes within which sufficient free radical polymerizable monomer, catalyst, and/or cross-linking agent can be contained therein without blocking the substrate 1, affecting the initial breathability of the substrate 1, and the particle size of the first and/or second microcapsules may be, for example, 0.5 μm, 1 μm, 3 μm, 5 μm, 7 μm, 9 μm, or 10 μm.
In an alternative embodiment, the thickness of the self-healing coating 2 is 0.5 μm to 6 μm. The thickness of the self-healing coating 2 may be, for example, 0.5 μm, 1 μm, 3 μm, 5 μm or 6 μm.
In some alternative embodiments, the self-healing coating 2 further comprises one or more functional aids selected from wetting agents, dispersants, and binders; for this purpose, the application provides a specific self-repairing coating 2 slurry, wherein the self-repairing coating 2 slurry further comprises a solvent, and the self-repairing coating 2 slurry comprises the following components in percentage by mass:
20-80% of solvent, 5-50% of first microcapsule and second microcapsule, 0-10% of wetting agent, 0-10% of wet dispersing agent and 0.05-20% of binder.
The solvent may be an aqueous solvent, such as deionized water, an organic solvent miscible with water, etc., which is not specifically limited in this application; the wetting agent is used for improving the surface tension of the self-repairing coating 2, and for example, the wetting agent can be one or more of polyvinylpyrrolidone, ethylene glycol, isopropanol, polyoxyethylene ether and organosilicon; the above-mentioned dispersing agent is used for enabling the microcapsules to be better dispersed in a solvent, and exemplified by ammonium polyacrylate salts, sulfonate salts, high molecular polyethers, alkyl quaternary ammonium salts, aminopropylamine dioleates, and the like; the above-mentioned adhesive is used to improve the adhesion of the self-repairing coating 2, and may be, for example, one or more of sodium hydroxymethyl cellulose, polyvinyl alcohol, polyacrylic acid, SBR (styrene-butadiene latex).
In some alternative embodiments, the pore size of the substrate 1 is 20nm to 100nm; for example, the pore size of the substrate 1 may be 20nm, 40nm, 60nm, 80nm or 100nm.
In some alternative embodiments, the porosity of the substrate 1 is 20% to 70%; for example, the porosity of the substrate 1 may be 20%, 30%, 40%, 50%, 60% or 70%.
The substrate 1 may be at least one selected from polyolefin, polyimide, polyvinylidene fluoride, polyamide, and cellulose.
In addition, the application also provides a secondary battery comprising the battery diaphragm.
In order to facilitate the description of the beneficial effects of the present application, the following more specific embodiments are also provided.
Comparative example one
A 16 μm porous polypropylene substrate 1 without self-healing coating 2 was prepared.
Comparative example two
A polypropylene substrate 1 having the same parameters as in comparative example 1 was prepared, and then a ceramic coating having a thickness of 2 μm was coated on the surface of the polypropylene substrate 1, and the ceramic particles in the ceramic coating had a particle size of 700nm.
Embodiment one:
urea and formaldehyde were mixed in a molar ratio of 1:1.75 and the pH of the mixture was adjusted to 9.0.
The mixture is stirred for 1 hour at a constant temperature of 75 ℃, and then distilled water is added for dilution, so as to obtain the urea formaldehyde prepolymer solution with the mass concentration of 35 percent.
10-20mL of urea formaldehyde prepolymer solution is taken, the pH value is regulated to 4.0, and then the reaction is carried out for 1 hour under the condition of 25 ℃ to obtain the water-soluble urea formaldehyde resin.
Dicyclopentadiene (DCPD) is dispersed in an oil phase to prepare a dispersion liquid with the mass fraction of 10%, and then 4.5mL of the dispersion liquid is added dropwise to the water-soluble urea-formaldehyde resin to form emulsion.
Then the pH value of the emulsion is regulated to 3.0, and after the reaction is carried out for 1 hour at 25 ℃, 0.3 to 3g of curing agent is added into the emulsion, the temperature is raised to 45 to 50 ℃, and the reaction is carried out for 2 hours at the temperature.
And (3) carrying out suction filtration and drying to obtain the first microcapsule with the first core layer 31a of DCPD and the first shell layer 31b of urea formaldehyde resin.
With reference to the above method for preparing the first microcapsule, the second microcapsule can be prepared by replacing DCPD with a granny catalyst.
Wherein the first microcapsule and the second microcapsule prepared by the above method have a particle size of 4.5 μm.
Two kinds of microcapsules are mixed according to a mass ratio of 1:1 into water to prepare slurry with the concentration of 30 percent by weight, then adding acrylic ester accounting for 5 percent by weight of the microcapsule, wetting agent accounting for 0.2 percent by weight and dispersing agent accounting for 0.1 percent by weight, and stirring for 1 hour to obtain the self-repairing coating 2 slurry.
The self-repairing coating 2 sizing agent is coated on two opposite sides of a polypropylene base material 1 (each parameter of the polypropylene base material is the same as that of a comparative example one) in a roller coating mode, and then the battery diaphragm is obtained. At this time, the SEM image of the surface of the battery separator is shown in fig. 4, and as can be seen from fig. 4, the self-repairing image 2 of the surface of the battery separator is loaded with a plurality of tiny particles, namely, a first microcapsule and a second microcapsule.
Examples two to ten
Referring to the method provided in the first embodiment, the second to tenth embodiments were prepared, wherein each parameter in the second to tenth embodiments is the same as that in the first embodiment, and the difference in the second to tenth embodiments is that the first and second microcapsules with different particle sizes were obtained by changing the molar ratio of urea to formaldehyde and the stirring rate. The specific differences are shown in table 1.
Table 1 parameters for the preparation of the self-healing coating 2 in examples two to ten
Examples Urea: formaldehyde (molar ratio) Stirring rate (rpm) Particle size (μm) Thickness of self-repairing coating (mum)
Example two 1：1.75 380 4.5 4.8
Example III 1：1.75 300 3.9 4.1
Example IV 1：1.75 250 5.1 5.9
Example five 1：1.5 300 2.8 3.4
Example six 1：1.5 250 2.4 2.7
Example seven 1：1 300 1.1 1.5
Example eight 1：1 250 1.3 1.6
Example nine 1: 0.75 300 0.5 0.5
Examples ten 1: 0.75 250 0.8 0.9
And (3) testing:
puncture resistance was tested for each of the above examples and comparative examples. The test method is as follows:
testing an initial ventilation value of the battery separator before puncture of the battery separator; then placing the sample battery diaphragm and the Teflon plate on a puncture fixture, keeping the surface of the sample flat and free of wrinkles, and pressing the battery diaphragm for 5 seconds by using a needle with the sectional area of 0.5mm with 2N force to finish needling; after the battery separator was needled, the air permeability of the battery separator was measured again. If the ventilation value of the battery separator can be improved before and after needling, the sample has good self-healing performance.
The air permeability value of the diaphragm is tested by referring to an air permeability test method described in GB/T458-2008, 3 samples are taken to be tested by adopting an air permeability instrument during testing, and the measured average value is taken as the air permeability value.
The specific test results are shown in table 2.
TABLE 2 puncture resistance Properties
Sequence number Initial ventilation value (s/100 mL) Ventilation value after needling (s/100 mL)
ExamplesA first part 220 698
Example two 211 678
Example III 218 786
Example IV 216 578
Example five 230 432
Example six 226 388
Example seven 247 281
Example eight 198 279
Example nine 202 203
Examples ten 225 230
Comparative example one 209 89
Comparative example two 221 43
As can be seen from the above table, the battery separator provided with the self-repairing coating layer provided in this example has an initial air permeation value which is not much different from that of comparative examples one and two; and the ventilation value of the battery diaphragm provided by the application is obviously reduced (the ventilation value is lower and the ventilation is higher) after needling, and the ventilation value of the battery diaphragm is not changed greatly or is increased before and after needling, so that the battery diaphragm provided by the application can be rapidly sealed after needling and has a self-repairing function, and the puncture resistance capability is indirectly obtained.
The foregoing description of the invention has been presented for purposes of illustration and description, and is not intended to be limiting. Several simple deductions, modifications or substitutions may also be made by a person skilled in the art to which the invention pertains, based on the idea of the invention.

Claims (10)

1. A battery separator, comprising: a substrate; and
a self-healing coating layer disposed on at least one side surface of the substrate; the self-healing coating includes a first microcapsule and a second microcapsule,
the first microcapsule is provided with a first shell layer and a first core layer, the first core layer is coated on the inner side of the first shell layer, and the first core layer comprises a free radical polymerization monomer;
the second microcapsule has a second shell layer and a second core layer, the second core layer is coated on the inner side of the second shell layer, and the second core layer contains a catalyst and/or a cross-linking agent for initiating the cross-linking of the free radical polymerization monomer.
2. The battery separator of claim 1, wherein the self-healing coating has a thickness of 10% to 40% of the total thickness of the battery separator.
3. The battery separator of claim 1, wherein the self-healing coating satisfies at least one of conditions (1) to (3):
(1) The particle size of the first microcapsule and/or the second microcapsule is 0.5-10 μm;
(2) The mass ratio of the first microcapsule to the second microcapsule is 1:1;
(3) The thickness of the self-repairing coating is 0.5-6 mu m.
4. The battery separator of any of claims 1-3, wherein the polymerized monomer comprises at least one of dicyclopentadiene, polydiethoxysiloxane, and hydroxyl-terminated polydimethylsiloxane.
5. The battery separator of any of claims 1-3, wherein the second core layer comprises at least one of a granny catalyst, di-n-butyltin dilaurate, a tungsten hexachloride phenylacetylene mixture, and an azide.
6. The battery separator of any one of claims 1 to 3, wherein the first shell layer comprises at least one of urea formaldehyde resin, epoxy resin, ceramic precursor resin, lecithin, fatty acid perhydro polysilazane, silica cyclodextrin, chitosan, sodium tripolyphosphate, polyurethane, polyethylene glycol, polyamide, and polyethylene.
7. The battery separator of any one of claims 1 to 3, wherein the second shell layer comprises at least one of urea formaldehyde resin, epoxy resin, ceramic precursor resin, lecithin, fatty acid perhydro polysilazane, silica cyclodextrin, chitosan, sodium tripolyphosphate, polyurethane, polyethylene glycol, polyamide, and polyethylene.
8. The battery separator of any of claims 1 to 3 wherein the self-healing coating further comprises one or more of a wetting agent, a dispersing agent, and a binder.
9. The battery separator according to any one of claims 1 to 3, wherein the substrate satisfies at least one of conditions (1) to (3):
(1) The aperture of the base material is 20nm-100nm;
(2) The porosity of the base material is 20% -70%;
(3) The substrate comprises at least one of polyolefin, polyimide, polyvinylidene fluoride, polyamide and cellulose.
10. A secondary battery comprising the battery separator according to any one of claims 1 to 9.
CN202311717486.6A 2023-12-14 2023-12-14 Battery separator and secondary battery Pending CN117410650A (en)

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