CN114583396A - High-safety lithium ion battery diaphragm and preparation method thereof - Google Patents
High-safety lithium ion battery diaphragm and preparation method thereof Download PDFInfo
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- CN114583396A CN114583396A CN202210283881.7A CN202210283881A CN114583396A CN 114583396 A CN114583396 A CN 114583396A CN 202210283881 A CN202210283881 A CN 202210283881A CN 114583396 A CN114583396 A CN 114583396A
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- particle
- inorganic oxide
- coating layer
- lithium ion
- ion battery
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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
- H01M50/457—Separators, membranes or diaphragms characterised by the material having a layered structure comprising three or more layers
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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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- 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
- H01M50/403—Manufacturing processes of separators, membranes or diaphragms
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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
- H01M50/411—Organic material
- H01M50/414—Synthetic resins, e.g. thermoplastics or thermosetting resins
- H01M50/417—Polyolefins
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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
- H01M50/431—Inorganic material
- H01M50/434—Ceramics
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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
Abstract
The invention provides a high-safety lithium ion battery diaphragm, which comprises a polyolefin base film; the first coating layer is coated on two sides of the base film and comprises large-particle-size inorganic oxide and temperature-resistant high polymer resin; the second coating layer is coated on one surface of the first coating layer, which is far away from the base film, and comprises small-particle-size inorganic oxide and temperature-resistant high-molecular resin.
Description
Technical Field
The invention relates to a high-safety lithium ion battery diaphragm and a preparation method thereof, belonging to the technical field of lithium ion battery materials.
Background
The diaphragm is an important component of the lithium ion battery, and the diaphragm mainly plays a role in separating the positive electrode and the negative electrode of the battery and preventing the positive electrode and the negative electrode from contacting to cause short circuit. The separator itself is a non-conductive material and has certain micropores and porosity that enable electrolyte ions to pass through. The performance of the diaphragm determines the interface structure, internal resistance and the like of the battery, and directly influences the capacity, cycle performance, safety performance and the like of the battery.
The lithium ion battery has the advantages of high energy density, high working voltage, long service life, low self-discharge rate, environmental friendliness and the like, is widely applied to the fields of portable electronic products (such as smart phones, digital cameras, notebook computers and the like), new energy automobiles and the like, and however, along with the rapid development of new energy industries such as electric automobiles, large-scale energy storage power grids and the like, higher requirements are provided for the safety performance of the lithium ion battery and the performance of the diaphragm.
In the prior art, a conventional coating diaphragm has high temperature resistance, and can effectively prevent a battery combustion accident caused by overheating inside the battery, however, the conventional coating diaphragm adopts a coating layer formed by compounding an adhesive and ceramic particles, and in the high-temperature process inside the battery, the ceramic has high temperature resistance, so that the aperture of the diaphragm cannot be closed, the positive electrode and the negative electrode of the battery are completely isolated, the electrochemical reaction path of the battery is completely lost, and the safety accident of the battery is easily caused in the high-temperature state.
CN113471629A discloses a diaphragm with a composite coating structure, which is formed by coating composite inorganic substance coatings on two sides of a polyolefin diaphragm, wherein the outer sides of the composite inorganic substance coatings are uniformly coated with resin layers, the outer sides of the resin layers are coated with ceramic layers, the outer parts of the ceramic layers are coated with acrylic glue layers, and each layer is provided with micropores, and the hollow microspheres in the composite inorganic substance coating on the surface of the polyolefin diaphragm, the high molecular elastomer is heated and melted at high temperature to become fluid to seal the second micropores on the composite inorganic coating, so that the diaphragm can quickly respond to realize closed pores when abnormal high temperature occurs in the battery, however, in the technical scheme, the resin layer is used as a high-temperature fusing agent, but the resin needs to be continuously melted at high temperature because the resin is high-temperature resistant, and the inorganic coating can be completely covered by the resin layer, so that the aim of effectively sealing the pores of the diaphragm is fulfilled.
Disclosure of Invention
The invention aims to provide a lithium ion battery diaphragm with a self-closing aperture function and a preparation method thereof, wherein a gradient inorganic oxide coating layer and a gradient macromolecule self-adhesive layer are adopted, on one hand, because the types of adhesives in each layer are different, the thicknesses of the adhesives are different, and the temperatures of thermal deformation and melting are different, when the battery is abnormally high, the instant loss caused by the instant hole sealing of the diaphragm when the battery is abnormally high can be effectively prevented, a working buffer space is provided for the battery, and meanwhile, the deflagration caused by the short circuit of the battery due to the deformation of the diaphragm when the battery is abnormally high can be effectively prevented. On the other hand, the gradient of the ceramic particles is mainly the gradient distribution of the particle size, and the effect is that after the adhesive is melted at high temperature, the small-particle ceramic can fill the gap of the large-particle ceramic, and the aperture of the diaphragm is completely sealed. Compared with the prior art, the invention has the greatest advantages that the high-temperature safety of the battery can be solved, meanwhile, the battery can be buffered instantaneously, and the loss of a carrier caused by instantaneous power failure is reduced.
In one aspect, the invention provides a lithium ion battery separator comprising
A polyolefin based film;
the first coating layer is coated on two sides of the base film and comprises large-particle-size inorganic oxide and temperature-resistant high polymer resin;
and the second coating layer is coated on one surface of the first coating layer, which is far away from the base film, and comprises small-particle-size inorganic oxide and temperature-resistant high polymer resin.
Preferably, the polyolefin-based film is a composite of one or more of polyethylene, polypropylene and polyimide.
Preferably, the large-particle-size inorganic oxide is one or two of aluminum oxide and titanium oxide, the particle size of the large-particle-size inorganic oxide is 25-65nm, and the large-particle-size inorganic oxide accounts for 55-70% of the total inorganic oxide.
Preferably, the small-particle-size inorganic oxide is one or two of aluminum oxide and titanium oxide, the particle size of the small-particle-size inorganic oxide is 20-60nm, and the small-particle-size inorganic oxide accounts for 30-45% of the total inorganic oxide.
Preferably, the thickness of the first coating layer is 0.5 to 1.5 μm, and the thickness of the second coating layer is 1 to 2 μm.
Preferably, the small-particle size inorganic oxide and the large-particle size inorganic oxide are spherical or spheroidal in shape.
Preferably, the temperature-resistant polymer resin is one or more of polyethylene, polypropylene or polyvinyl chloride.
Preferably, the proportion of the temperature-resistant polymer resin in the first coating layer in the total resin layer is 55-70%, and the proportion of the temperature-resistant polymer resin in the second coating layer in the total resin layer is 30-45%.
In another aspect, the present invention further provides a method for preparing the lithium ion battery separator, including the following steps:
(1) providing a polyolefin base film;
(2) mixing large-particle-size inorganic oxide particles with temperature-resistant high-molecular resin, and coating the mixture on two sides of a polyolefin base film to form a first coating layer;
(3) mixing small-particle-size inorganic oxide particles with temperature-resistant high-molecular resin, and coating the mixture on one surface of the first coating layer, which is far away from the base film, to form a second coating layer;
(4) and after coating, drying and shaping to obtain the lithium ion battery diaphragm.
Preferably, the mass ratio of the large-particle-size inorganic oxide particles to the temperature-resistant polymer resin is (1-5): 1; the mass ratio of the small-particle-size inorganic oxide particles to the temperature-resistant polymer resin is (1-5): 1. .
The invention has the beneficial effects that: in the prior art, PVDF is generally adopted as an adhesive, and the PVDF as the adhesive has poor compatibility due to different physical properties with a polyolefin matrix, has the defect of low bonding strength with the polyolefin diaphragm matrix, and has the defects of poor dispersion performance and uneven coating. In order to solve the technical problem of the PVDF adhesive used for coating in the prior art, resin with physical properties similar to or the same as that of polyolefin is used as the adhesive, gradient modes with different particle sizes and different coating thicknesses are adopted, inorganic particles are spherical or sphere-like, a network is formed by connecting the inorganic particles by virtue of the adhesive, when a coated diaphragm is heated, the adhesive is melted, small-particle-size inorganic coating particles fall into gaps of large-particle-size inorganic coating particles, and the gaps of the large-particle-size inorganic coating particles are filled with the resin adhesive, so that the diaphragm is completely closed, the electrochemical reaction condition of the battery is lost, and the high-temperature safety performance of the battery is effectively guaranteed.
Drawings
FIG. 1 is a schematic diagram of a separator with a composite coating structure of the present invention, wherein 1 is a polyolefin-based film, 2 is a first coating layer, and 3 is a second coating layer;
fig. 2 is a schematic diagram of inorganic oxide distribution, wherein 4 is large-particle inorganic oxide and 5 is small-particle inorganic oxide.
Detailed Description
In order to better explain the invention, refer to the implementation of the invention detailed description, and combine the specific examples to further clarify the main content of the invention, but the content of the invention is not limited to the following examples only. The examples, where specific techniques or conditions are not indicated, are to be construed according to the techniques or conditions described in the literature in the art or according to the product specifications. The reagents or instruments used are conventional products which are commercially available, and are not indicated by manufacturers.
Example 1
Titanium oxide with the particle size of 25nm is compounded on the surface of a polyethylene base film with the thickness of 7 mu m, the porosity of 40% and the pore diameter of 10nm by adopting polypropylene as an adhesive to form a first coating layer, and the mixing ratio of the titanium oxide to the polypropylene is 70%: 30 percent (mass ratio), the thickness of the coating layer is 0.5 mu m, wherein the mass of the titanium oxide with large particle size accounts for 55 percent of the mass of the total inorganic oxide; mixing small-particle-size alumina with the particle size of 20nm with polyvinyl chloride resin, and coating the mixture on the surface of the first coating layer according to a conventional coating process to form a second coating layer, wherein the mixing ratio of the alumina to the polyvinyl chloride is 80%: 20 percent (mass ratio), and the coating is uniformly coated on the two sides of the polyethylene diaphragm by adopting a conventional coating process, the thickness of the coating layer is 1 mu m, wherein the mass ratio of the small-particle-size alumina to the total mass of the coated inorganic oxide is 30 percent. After coating, the product of the invention is obtained after drying and shaping.
Comparative example 1
On the surface of a polyethylene base membrane with the thickness of 7 mu m, the porosity of 40 percent and the pore diameter of 10nm, alumina ceramic particles, PVDF and other solvents are mixed and stirred evenly, and the two sides of the polyethylene membrane are coated evenly, wherein the particle size of the alumina ceramic particles is 300nm, and the coating thickness is 1 mu m.
The properties of the separators obtained in example 1 and comparative example 1 were compared, and the results are shown in table 1.
TABLE 1 comparison of sample testing
| Item | Example 1 | Comparative example 1 |
| Film thickness | 9 | 9 |
| Temperature resistance | 185℃ | 180℃ |
| Shrinkage (180 ℃, 1h) | 0 | 3％ |
| Porosity of the material | 48％ | 42％ |
| Specific capacity | 285mAh/g | 260mAh/g |
As can be seen from the data in Table 1, the performance of the diaphragm prepared by the invention is better than that of the diaphragm prepared by the comparative example 1, the shrinkage rate at 180 ℃ is 0, and the temperature resistance, the porosity and the specific capacity are all improved.
Claims (10)
1. A high-safety lithium ion battery diaphragm is characterized by comprising
A polyolefin based film;
the first coating layer is coated on two sides of the base film and comprises large-particle-size inorganic oxide and temperature-resistant high polymer resin;
and the second coating layer is coated on one surface of the first coating layer, which is far away from the base film, and comprises small-particle-size inorganic oxide and temperature-resistant high polymer resin.
2. The high-safety lithium ion battery separator according to claim 1, wherein the polyolefin-based film is one or more of polyethylene, polypropylene and polyimide.
3. The high-safety lithium ion battery separator according to claim 1, wherein the large-particle-size inorganic oxide is one or both of alumina and titania, the large-particle-size inorganic oxide has a particle size of 25 to 65nm, and the large-particle-size inorganic oxide accounts for 55 to 70% of the total inorganic oxide.
4. The high-safety lithium ion battery separator as claimed in claim 1, wherein the small-particle-size inorganic oxide is one or both of alumina and titania, the particle size of the small-particle-size inorganic oxide is 20-60nm, and the small-particle-size inorganic oxide accounts for 30-45% of the total inorganic oxide.
5. The high-safety lithium ion battery separator according to claim 1, wherein the thickness of the first coating layer is 0.5-1.5 μm, and the thickness of the second coating layer is 1-2 μm.
6. The high safety lithium ion battery separator according to any one of claims 1 to 5, wherein the small-particle size inorganic oxide and the large-particle size inorganic oxide have a spherical or spheroidal shape.
7. The high-safety lithium ion battery separator according to any one of claims 1 to 5, wherein the temperature-resistant polymer resin is one or more of polyethylene, polypropylene or polyvinyl chloride, and the temperature-resistant polymer resins of the second coating layer and the first coating layer are different in kind.
8. The high-safety lithium ion battery separator according to claim 7, wherein the proportion of the temperature-resistant polymer resin in the first coating layer in the total resin layer is 55-70%, and the proportion of the temperature-resistant polymer resin in the second coating layer in the total resin layer is 30-45%.
9. A preparation method of the high-safety lithium ion battery separator as claimed in any one of claims 1 to 8, characterized by comprising the following steps:
(1) providing a polyolefin base film;
(2) mixing large-particle-size inorganic oxide particles with temperature-resistant high-molecular resin, and coating the mixture on two sides of a polyolefin base film to form a first coating layer;
(3) mixing small-particle-size inorganic oxide particles with temperature-resistant high-molecular resin, and coating the mixture on one surface of the first coating layer, which is far away from the base film, to form a second coating layer;
(4) and after the coating is finished, drying and shaping to obtain the lithium ion battery diaphragm.
10. The preparation method of the lithium ion battery separator according to claim 9, wherein the mass ratio of the large-particle-size inorganic oxide particles to the temperature-resistant polymer resin is (1-5): 1; the mass ratio of the small-particle-size inorganic oxide particles to the temperature-resistant polymer resin is (1-5): 1.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202210283881.7A CN114583396A (en) | 2022-03-22 | 2022-03-22 | High-safety lithium ion battery diaphragm and preparation method thereof |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202210283881.7A CN114583396A (en) | 2022-03-22 | 2022-03-22 | High-safety lithium ion battery diaphragm and preparation method thereof |
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| Publication Number | Publication Date |
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| CN114583396A true CN114583396A (en) | 2022-06-03 |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202210283881.7A Withdrawn CN114583396A (en) | 2022-03-22 | 2022-03-22 | High-safety lithium ion battery diaphragm and preparation method thereof |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114709562A (en) * | 2022-06-07 | 2022-07-05 | 中材锂膜(宁乡)有限公司 | Separator, method for producing separator, and electrochemical device |
-
2022
- 2022-03-22 CN CN202210283881.7A patent/CN114583396A/en not_active Withdrawn
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114709562A (en) * | 2022-06-07 | 2022-07-05 | 中材锂膜(宁乡)有限公司 | Separator, method for producing separator, and electrochemical device |
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Application publication date: 20220603 |
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