CN112864530A - Thin coating film with double safety valves - Google Patents
Thin coating film with double safety valves Download PDFInfo
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- CN112864530A CN112864530A CN201911188464.9A CN201911188464A CN112864530A CN 112864530 A CN112864530 A CN 112864530A CN 201911188464 A CN201911188464 A CN 201911188464A CN 112864530 A CN112864530 A CN 112864530A
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- Prior art keywords
- safety valve
- thin coating
- coating film
- film
- base film
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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
-
- 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 relates to a thin coating film with a double safety valve, which comprises a base film and a coating layer, wherein the coating layer is positioned on at least one surface of the base film and comprises a ceramic slurry layer and an organic particle slurry layer or a mixed slurry of ceramic and organic particles; the melting point of the base film raw material is 90-130 ℃, the melting point of organic particles in the coating slurry is 60-90 ℃, and the closed pore temperature of the thin coating film is 130-170 ℃; at 170 ℃, the heat shrinkage ratio in the length direction MD/the heat shrinkage ratio in the width direction TD is less than 2%, and the air permeability increase value is more than or equal to 3000sec/100 ml. The safety coefficient of the battery is improved by arranging the function of the double-layer safety valve.
Description
Technical Field
The invention relates to the technical field of diaphragms, in particular to a thin coating film with double safety valves.
Background
The diaphragm is used as an important component of the lithium ion battery, has the functions of isolating the positive electrode and the negative electrode to prevent short circuit and simultaneously enabling lithium ions to be conducted between the positive electrode and the negative electrode, and the performance of the diaphragm determines the internal resistance and the interface structure of the lithium battery, influences the capacity and the cycle performance of the battery and is closely related to the safety of the lithium battery. The lithium battery diaphragm material used in the market at present is mainly polyolefin, and can be divided into a dry diaphragm (melt stretching) and a wet diaphragm (thermally induced phase separation) according to the production process, wherein the polypropylene lithium battery diaphragm is produced by the dry process, and the polyethylene battery diaphragm is prepared by the wet process. The polyolefin separator has many advantages, but also has the defects of poor mechanical property, poor liquid retention capability, low ionic conductivity and the like. The polyolefin diaphragm has the defects that potential safety hazards exist in the use process of the lithium battery, for example, in the recycling process of the lithium battery, the volume expansion of the positive electrode and the negative electrode can provide certain extrusion force for the diaphragm, so that the diaphragm fails to work, and the potential safety hazards are caused. During the charging and discharging processes of the lithium ion battery, the generated lithium dendrite may puncture the diaphragm and also cause local short circuit in the battery, so that the current is concentrated on the punctured part of the diaphragm to cause overheating and fire or explosion. The lithium ion battery may be deformed too much by external impact, so that the diaphragm is deformed or even broken, and further, the anode and the cathode are in direct contact to cause short circuit, thereby causing fire or explosion. Because of the disadvantage of poor liquid retention property, on one hand, the redundant flammable electrolyte in the lithium ion battery may leak, and on the other hand, the use process of the lithium ion battery always accompanies with the loss of the electrolyte, and the insufficient electrolyte causes the internal resistance of the lithium ion battery to increase and the cycle performance to decrease. Therefore, the safety coefficient of the battery is improved by arranging the function of the double-layer safety valve.
Disclosure of Invention
The invention aims to overcome the defects of the prior art and provide a thin coating film with a safety valve and a lithium battery thereof.
The purpose of the invention is realized by the following technical scheme:
a thin coating film with a double safety valve includes a base film and a coating layer coated on at least one side of the base film.
The melting point of the base film raw material is 90-130 ℃.
The closed pore temperature of the thin coating film is 130-170 ℃.
At 170 ℃, the heat shrinkage ratio MD in the length direction/the heat shrinkage ratio TD in the width direction is less than or equal to 2%, and the air permeability increase value is more than 3000sec/100 ml.
The thickness of the base film is 3-11 microns, preferably 5-9 microns.
The raw material of the base film is polyolefin, preferably polyethylene, the melting point of the polyethylene is 60-130 ℃, the molecular weight is 10-60 w, and the particle size is 0.1 nanometer-5 micrometers.
The organic particle is made of polyethylene or polypropylene material, and the melting point is 60-130 ℃.
The closed pore temperature of the thin coating film is 140-160 ℃.
The closed pore temperature of the thin coating film is 155-160 ℃.
The coating layer comprises inorganic particles, organic particles and a binder; a coating layer is formed on at least one surface of a base film to which the slurry is applied.
The inorganic particles are alumina, silica, magnesia, boehmite, etc.
The melting point of polyolefin in the coating slurry is 60-90 ℃.
The polyolefin is at least one of a modified high-density polyolefin, an unmodified high-density polyolefin and a high-density oxidized polyolefin.
The particle size of the polyolefin is 0.01-10 μm.
The binder is meta-aramid, PAA, PVA, PI, CMC and the like, and is preferably meta-aramid.
The mass fraction of the inorganic particles in the coating layer is 70-99%.
The thickness of the coating layer is 0.1-5 microns.
The fusing temperature of the coating layer is more than or equal to 200 ℃.
A lithium battery is characterized by comprising the diaphragm.
Compared with the prior art, the invention has the following positive effects:
when the temperature of the battery is raised to 60 ℃, because the melting point of the polyolefin in the coating is 60-90 ℃, the polyolefin in the coating is melted after reaching the melting point, and the holes of the diaphragm are closed by melting and blocking at high temperature, so that the purpose of safe shape fixation is achieved, and the function of a first layer of safety valve is achieved.
When the temperature of the battery is increased to 130 ℃, the polyolefin in the base film and the coating layer is completely melted, and the inorganic matters in the coating layer can fix the polyolefin in the molten state, prevent the polyolefin from shrinking and still keep the size and shape of the diaphragm unchanged, thereby playing the function of a second layer of safety valve.
In addition, when the temperature of the battery is increased to 60 ℃, if the melting point of the polyolefin in the coating is lower than 60 ℃, the polyolefin in the coating can be melted, and the holes of the diaphragm can be closed by the melted blocking holes at high temperature, so that the diaphragm is closed, and the normal performance of the battery can be influenced because the closing temperature of the diaphragm is too low;
when the melting point of the polyolefin in the coating is higher than 130 ℃, the shrinkage speed of the base film at high temperature is higher than the melting speed of the polyolefin, so that the base film cannot play a role of a first layer of safety valve;
when the closed cell temperature of the thin coating film is less than 130 c, the base film is closed before the cell temperature rises to 130 c, at which time the movement of electrons is effectively blocked although the separator can still withstand high temperatures, so that the function of the second safety valve is not required.
When the closed pore temperature of the thin coating film is higher than 170 ℃, inorganic matters in the coating cannot prevent the thermal shrinkage of the diaphragm at the high temperature, the diaphragm can generate obvious thermal shrinkage, and the anode and the cathode of the battery can be in direct contact to generate short circuit, so that the thin coating film cannot play a role of a second layer of safety valve.
Detailed Description
The following provides specific embodiments of a thin coating film having a double safety valve and a lithium battery using the same.
Example 1
A thin coating film with a double safety valve includes a base film and a coating layer coated on at least one side of the base film.
The melting point of the base film raw material is 90 ℃;
the closed pore temperature of the thin coating film is 130 ℃;
the heat shrinkage ratio in the longitudinal direction MD/the heat shrinkage ratio in the width direction TD was less than 2% at 170 ℃ and the air permeability increase was 3100sec/100 ml.
The thickness of the base film was 5 μm.
The raw material of the base film is polyolefin, preferably polyethylene, the molecular weight is 10-60 w, and the particle size is 0.1-5 microns.
The coating layer comprises inorganic particles, organic particles and a binder; a coating layer is formed on at least one surface of a base film to which the slurry is applied.
The inorganic particles are alumina.
The organic particles are polyethylene.
The binder is meta-aramid.
The mass fraction of the inorganic particles in the coating layer was 70%.
The thickness of the coating layer was 1.5 μm.
The fusing temperature of the coating layer is more than 200 ℃.
Example 2
A thin coating film with a double safety valve includes a base film and a coating layer coated on at least one side of the base film.
The melting point of the base film raw material is 90 ℃;
the melting point of the polyolefin in the coating is 70 ℃;
the closed pore temperature of the thin coating film is 140 ℃;
at 170 ℃, the heat shrinkage ratio in the length direction MD/heat shrinkage ratio in the width direction TD is less than 1.6%, and the air permeability increase value is more than 3200sec/100 ml.
The thickness of the base film was 5 μm.
The base film is made of polyolefin, preferably polypropylene, the molecular weight is 10-60 w, and the particle size is 0.1-5 microns.
The coating layer comprises inorganic particles, organic particles and a binder; a coating layer is formed on at least one surface of a base film to which the slurry is applied.
The inorganic particles are silicon oxide.
The organic particles are polyethylene.
The binder is PAA.
The mass fraction of the inorganic particles in the coating layer was 78%.
The thickness of the coating layer was 2 μm.
The fusing temperature of the coating layer is more than 200 ℃.
Example 3
A thin coating film with a double safety valve includes a base film and a coating layer coated on at least one side of the base film.
The melting point of the base film raw material is 100 ℃;
the closed pore temperature of the thin coating film is 150 ℃;
at 170 ℃, the heat shrinkage ratio in the length direction MD/heat shrinkage ratio in the width direction TD is less than 1.5%, and the air permeability increase value is more than 3300sec/100 ml.
The thickness of the base film was 7 μm.
The raw material of the base film is polyolefin, preferably polyethylene, the molecular weight is 10-60 w, and the particle size is 0.1-5 microns.
The coating layer comprises inorganic particles, organic particles and a binder; a coating layer is formed on at least one surface of a base film to which the slurry is applied.
The inorganic particles are boehmite.
The organic particles are polypropylene.
The binder is PVA.
The mass fraction of the inorganic particles in the coating layer was 85%.
The thickness of the coating layer was 2 μm.
The fusing temperature of the coating layer is more than 200 ℃.
Example 4
A thin coating film with a double safety valve includes a base film and a coating layer coated on at least one side of the base film.
The melting point of the base film raw material is 100 ℃;
the closed pore temperature of the thin coating film is 150 ℃;
the heat shrinkage ratio in the longitudinal direction MD/heat shrinkage ratio in the width direction TD at 170 ℃ is less than 1.2%, and the air permeability increase value is more than 3400sec/100 ml.
The thickness of the base film was 9 μm.
The raw material of the base film is polyolefin, preferably polyethylene, the molecular weight is 10-60 w, and the particle size is 0.1-5 microns.
The coating layer comprises inorganic particles, organic particles and a binder; a coating layer is formed on at least one surface of a base film to which the slurry is applied.
The inorganic particles are alumina.
The polyolefin is polyethylene.
The binder is meta-aramid.
The mass fraction of the inorganic particles in the coating layer was 85%.
The thickness of the coating layer was 3 μm.
The fusing temperature of the coating layer is more than 200 ℃.
Example 5
A thin coating film with a double safety valve includes a base film and a coating layer coated on at least one side of the base film.
The melting point of the base film raw material is 120 ℃;
the closed pore temperature of the thin coating film is 160 ℃;
the heat shrinkage ratio MD in the length direction/the heat shrinkage ratio TD in the width direction is less than 1% at 170 ℃, and the air permeability increase value is more than 3500sec/100 ml.
The thickness of the base film was 8 μm.
The raw material of the base film is polyolefin, preferably polyethylene, the molecular weight is 10-60 w, and the particle size is 0.1-5 microns.
The coating layer comprises inorganic particles, organic particles and a binder; a coating layer is formed on at least one surface of a base film to which the slurry is applied.
The inorganic particles are silicon oxide.
The organic particles are polypropylene.
The binder is PI.
The mass fraction of the inorganic particles in the coating layer was 90%.
The thickness of the coating layer was 4 μm.
The fusing temperature of the coating layer is more than 200 ℃.
Example 6
A thin coating film with a double safety valve includes a base film and a coating layer coated on at least one side of the base film.
The melting point of the base film raw material is 130 ℃;
the closed pore temperature of the thin coating film is 170 ℃;
at 170 ℃, the heat shrinkage ratio MD in the length direction/the heat shrinkage ratio TD in the width direction is less than 0.5%, and the air permeability increase value is more than 3800sec/100 ml.
The thickness of the base film was 11 μm.
The raw material of the base film is polyolefin, preferably polyethylene, the molecular weight is 10-60 w, and the particle size is 0.1-5 microns.
The coating layer comprises inorganic particles, organic particles and a binder; a coating layer is formed on at least one surface of a base film to which the slurry is applied.
The inorganic particles are alumina.
The organic particles are polyethylene.
The binder is meta-aramid.
The mass fraction of the inorganic particles in the coating layer was 95%.
The thickness of the coating layer was 5 μm.
The fusing temperature of the coating layer is more than 200 ℃.
Comparative example 1
A coated film having a base film and a coating layer, the coating layer being applied on at least one side of the base film.
The melting point of the base film raw material is 130 ℃;
the closed pore temperature of the thin coating film is 140 ℃;
the thickness of the base film was 9 μm.
The raw material of the base film is polyolefin, preferably polyethylene, the molecular weight is 10-60 w, and the particle size is 0.1-5 microns.
The coating layer comprises inorganic particles and a binder; a coating layer is formed on at least one surface of a base film to which the slurry is applied.
The inorganic particles are alumina.
The binder is meta-aramid.
The mass fraction of the inorganic particles in the coating layer was 95%.
The thickness of the coating layer was 3 μm.
The fusing temperature of the coating layer was 170 ℃.
Comparative example 2
A coated film having a base film and a coating layer, the coating layer being applied on at least one side of the base film.
The melting point of the base film raw material is 130 ℃;
the closed pore temperature of the thin coating film is 150 ℃;
the thickness of the base film was 12 μm.
The raw material of the base film is polyolefin, preferably polyethylene, the molecular weight is 10-60 w, and the particle size is 0.1-5 microns.
The coating layer comprises inorganic particles and a binder; a coating layer is formed on at least one surface of a base film to which the slurry is applied.
The inorganic particles are alumina.
The binder is meta-aramid.
The mass fraction of the inorganic particles in the coating layer was 95%.
The thickness of the coating layer was 5 μm.
The fusing temperature of the coating layer was 180 ℃.
The foregoing is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, several modifications and decorations can be made without departing from the concept of the present invention, and these modifications and decorations should also be regarded as being within the protection scope of the present invention.
Claims (14)
1. A thin coating film having a double safety valve, comprising a base film and a coating layer, the coating layer being applied on at least one side of the base film;
the melting point of the base film raw material is 90-130 ℃;
the melting point of organic particles in the coating slurry is 60-90 ℃;
the closed pore temperature of the thin coating film is 130-170 ℃;
at 170 ℃, the heat shrinkage ratio MD in the length direction/the heat shrinkage ratio TD in the width direction is less than or equal to 2%, and the air permeability increase value is more than 3000sec/100 ml.
2. The thin coating film with a double safety valve according to claim 1, wherein the thickness of the base film is 3 to 11 μm.
3. The thin coating film with a double safety valve according to claim 1, wherein the thickness of the base film is 5 to 9 μm.
4. The thin coating film with a double safety valve according to claim 1, wherein the base film is made of polyolefin.
5. The thin coating film with a double safety valve according to claim 4, wherein the organic particles are polyolefin and modified products thereof, the molecular weight is 10-60 w, and the particle size is 0.1 nm-5 μm.
6. The thin coating film with a double safety valve according to claim 1, wherein the thin coating film has a closed-cell temperature of 140 to 160 ℃.
7. The thin coating film with a double safety valve according to claim 1, wherein the thin coating film has a closed cell temperature of 155 to 160 ℃.
8. The thin coating film with a double safety valve according to claim 1, wherein the coating layer comprises inorganic particles, organic particles and a binder.
9. The thin coated film with a double safety valve according to claim 8, wherein the binder is one of meta-aramid, PAA, PVA, PI, CMC.
10. The thin coated film with a double safety valve according to claim 8, wherein the binder is meta-aramid.
11. The thin coating film with double safety valves according to claim 8, wherein the mass fraction of the inorganic particles in the coating layer is 70 to 99%.
12. The thin coating film with a double safety valve according to claim 8, wherein the thickness of the coating layer is 0.1 to 5 μm.
13. The thin coating film having a double safety valve according to claim 1, wherein the coating layer has a fusing temperature of 200 ℃ or higher.
14. A lithium battery comprising the separator according to any one of claims 1 to 13.
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| Application Number | Priority Date | Filing Date | Title |
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| CN201911188464.9A CN112864530A (en) | 2019-11-28 | 2019-11-28 | Thin coating film with double safety valves |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113690547A (en) * | 2021-08-03 | 2021-11-23 | 惠州锂威新能源科技有限公司 | Safety diaphragm, preparation method and lithium ion battery |
| CN113690548A (en) * | 2021-08-03 | 2021-11-23 | 惠州锂威新能源科技有限公司 | Safety diaphragm, preparation method thereof and lithium ion battery |
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| CN102437302A (en) * | 2011-11-25 | 2012-05-02 | 东莞市比比克电子科技有限公司 | Lithium ion battery diaphragm and high temperature thermal-stable lithium ion battery |
| CN105304850A (en) * | 2015-09-17 | 2016-02-03 | 中航锂电（洛阳）有限公司 | Mixed paint for composite membrane of lithium ion battery, composite membrane and preparation method thereof, and lithium ion battery |
| CN106252570A (en) * | 2016-08-31 | 2016-12-21 | 天津市捷威动力工业有限公司 | A kind of barrier film coating paste, composite heat resistance barrier film and preparation method thereof |
| CN106684299A (en) * | 2017-02-06 | 2017-05-17 | 旭成（福建）科技股份有限公司 | Ceramic coating with closed-cell properties and lithium ion battery diaphragm containing ceramic coating |
| CN110364660A (en) * | 2018-04-10 | 2019-10-22 | 中国科学院上海硅酸盐研究所 | A kind of water system Zinc ion battery composite diaphragm and preparation method |
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2019
- 2019-11-28 CN CN201911188464.9A patent/CN112864530A/en active Pending
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN102437302A (en) * | 2011-11-25 | 2012-05-02 | 东莞市比比克电子科技有限公司 | Lithium ion battery diaphragm and high temperature thermal-stable lithium ion battery |
| CN105304850A (en) * | 2015-09-17 | 2016-02-03 | 中航锂电（洛阳）有限公司 | Mixed paint for composite membrane of lithium ion battery, composite membrane and preparation method thereof, and lithium ion battery |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113690547A (en) * | 2021-08-03 | 2021-11-23 | 惠州锂威新能源科技有限公司 | Safety diaphragm, preparation method and lithium ion battery |
| CN113690548A (en) * | 2021-08-03 | 2021-11-23 | 惠州锂威新能源科技有限公司 | Safety diaphragm, preparation method thereof and lithium ion battery |
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