CN109994689B - Flame-retardant material, diaphragm, preparation method, secondary battery and electronic equipment - Google Patents
Flame-retardant material, diaphragm, preparation method, secondary battery and electronic equipment Download PDFInfo
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- CN109994689B CN109994689B CN201711484346.3A CN201711484346A CN109994689B CN 109994689 B CN109994689 B CN 109994689B CN 201711484346 A CN201711484346 A CN 201711484346A CN 109994689 B CN109994689 B CN 109994689B
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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
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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
- H01M50/449—Separators, membranes or diaphragms characterised by the material having a layered structure
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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 disclosure relates to a flame-retardant material, a diaphragm, a preparation method of the flame-retardant material, a secondary battery and electronic equipment, and belongs to the technical field of secondary batteries. Wherein the flame retardant material comprises: the flame retardant coating comprises a base body with a plurality of pore channels, a flame retardant filled in at least one pore channel of the base body and a protective layer coated outside the base body. When the flame retardant material provided by the disclosure is applied to a secondary battery, the secondary battery can be prevented from burning when the secondary battery is in an abuse state, and the performance of the secondary battery in a normal use state is not influenced.
Description
Technical Field
The disclosure relates to the technical field of secondary batteries, in particular to a flame-retardant material, a diaphragm, a preparation method of the flame-retardant material, a secondary battery and electronic equipment.
Background
A secondary battery, also called a rechargeable battery, is a battery that can be continuously used by activating an active material by charging after discharge. The secondary battery mainly includes a positive electrode, a negative electrode, and a separator and an electrolyte between the positive electrode and the negative electrode. Wherein the electrolyte is used for providing a medium for ion exchange; the separator serves to separate the positive and negative electrodes to prevent the positive and negative electrodes from contacting to cause a short circuit while ensuring the passage of ions. At present, electrolytes of secondary batteries are mainly organic electrolytes, such as carbonate electrolytes. The organic electrolyte can be burnt at a certain temperature, so that the secondary battery can be burnt after the internal temperature of the secondary battery reaches the burning temperature of the organic electrolyte due to abuse of the secondary battery and the like, and the personal and property safety of a user is seriously threatened. Therefore, it is necessary to add a flame retardant material to the secondary battery to prevent the secondary battery from burning.
A flame retardant material for a secondary battery is provided in the related art, and includes a flame retardant and a protective layer coated outside the flame retardant. The protective layer is mainly an organic polymer layer, an inorganic oxide layer or a composite layer of the organic polymer layer and the inorganic oxide layer. When the internal temperature of the secondary battery exceeds the melting point of the protective layer, the protective layer melts to release the flame retardant, or when the boiling point of the flame retardant is exceeded, the flame retardant vaporizes and is released from the protective layer. The flame retardant is released and then brought into contact with the organic electrolyte, thereby preventing the secondary battery from burning.
The related art has at least the following problems;
when the secondary battery is normally used, the organic electrolyte enters the inside of the protective layer to dissolve the fire retardant, so that the fire retardant enters the organic electrolyte. The flame retardant may affect the performance of the organic electrolyte, and further affect the performance of the secondary battery in a normal use state.
BRIEF SUMMARY OF THE PRESENT DISCLOSURE
In order to solve the technical problems, embodiments of the present disclosure provide a flame retardant material and a preparation method thereof, which can prevent the secondary battery from burning when the secondary battery is in an abuse state, and do not affect the performance of the secondary battery in a normal use state, and a separator, a preparation method thereof, a secondary battery, and an electronic device based on the flame retardant material.
Specifically, the method comprises the following technical scheme:
in a first aspect, embodiments of the present disclosure provide a flame retardant material, including:
a substrate having a plurality of cells therein,
a flame retardant filled in at least one of the channels of the substrate,
and the protective layer is coated outside the matrix.
In the flame retardant material provided by the embodiment of the disclosure, the flame retardant is filled in the pore channel of the substrate, the protective layer is coated outside the substrate, and the flame retardant can be effectively isolated from the external environment through the combined action of the pore channel structure of the substrate and the protective layer. When the external environment temperature reaches the boiling point of the flame retardant, the flame retardant is gasified and released to the external environment to play a flame-retardant role. Based on this, the flame retardant material provided by the embodiment of the disclosure is added to the secondary battery, when the secondary battery normally works, the flame retardant is in a liquid state or a solid state, and under the combined action of the pore structure of the substrate and the protective layer, the electrolyte can be effectively prevented from contacting the flame retardant, so that the flame retardant is effectively prevented from entering the electrolyte and affecting the performance of the secondary battery when the secondary battery normally works. When the internal temperature of the secondary battery rises due to abuse and other factors and reaches the boiling point of the flame retardant, the flame retardant is released to contact with the electrolyte, so that the flame retardant effect is achieved, and the secondary battery is prevented from burning. It can be seen that the flame retardant provided by the embodiments of the present disclosure can prevent the secondary battery from burning when the secondary battery is in an abusive state, and does not affect the performance of the secondary battery in a normal use state.
In addition, the flame retardant in the flame retardant material provided by the embodiment of the disclosure can be a liquid flame retardant at normal temperature, so that the selection range of the flame retardant is expanded.
In one possible design, the proportion of the number of the channels filled with the flame retardant in the matrix to the number of all the channels is more than 10%, or more than 20%, more than 30%, more than 40%, more than 50%, more than 60%, more than 70%, more than 80%, more than 90%, 100%, and the like.
In another possible design, in the pore channels filled with the flame retardant, the volume of the flame retardant accounts for more than 10% of the volume of the pore channels, or more than 20%, more than 30%, more than 40%, more than 50%, more than 60%, more than 70%, more than 80%, more than 90%, 100%, and the like.
In another possible design, the volume of the flame retardant accounts for less than 50% of the volume of the pore channel, and the flame retardant is positioned at a position close to the opening of the pore channel, so that the flame retardant is rapidly released, and the flame retardant effect is improved.
The shape of the substrate is prismatic, cylindrical or spherical; the pore channels are parallel to each other and are parallel to the axis of the base body.
In another possible design, the mass ratio of the flame retardant to the substrate is: (0.01-10) 1; the thickness of the protective layer is as follows: 0.01-10 microns.
In another possible design, the material of the matrix is a mesoporous material.
The mesoporous material has the characteristics of large specific surface area, regular and ordered pore channels, narrow pore channel diameter distribution and the like. The mesoporous material is adopted, so that the flame retardant can be effectively adsorbed under the normal working state of the secondary battery, the flame retardant is prevented from entering electrolyte to influence the performance of the secondary battery, and after the internal temperature of the secondary battery rises to exceed the boiling point of the flame retardant due to abuse and the like, the flame retardant can be quickly released to prevent combustion.
In another possible design, the material of the matrix is mesoporous carbon, mesoporous silica or mesoporous alumina.
In another possible design, the material of the matrix is mesoporous carbon with pore canal diameter of 2 nm-10 nm and particle size of 200 nm-2 μm.
In another possible design, the material of the protective layer is an organic polymer.
The melting point of the organic polymer is generally lower than the boiling point of the flame retardant, so when the interior of the secondary battery rises to reach the boiling point of the flame retardant, the organic polymer is melted, and the flame retardant is directly released from the pore channel of the substrate to the external environment, thereby being beneficial to the quick release of the flame retardant.
In another possible design, the material of the protective layer is selected from at least one of polyvinylidene fluoride, vinylidene fluoride-hexafluoropropylene copolymer, polymethyl methacrylate, polyacrylamide, polyvinyl alcohol, polyimide, polyethylene, polypropylene, polyacrylonitrile, and polyacrylic acid.
In another possible design, the weight average molecular weight of the organic polymer is 1000 to 1000000.
In another possible design, the flame retardant is selected from at least one of an organic phosphorus-based flame retardant, an inorganic phosphate-based flame retardant, a nitrogen-containing compound flame retardant, a halogen-based flame retardant, and a silicon-based flame retardant.
In a second aspect, embodiments of the present disclosure provide a method for preparing a flame retardant material, including the following steps:
enabling the flame retardant in a molten state to enter at least one pore channel of the substrate with a plurality of pore channels to obtain the substrate filled with the flame retardant;
and forming a protective layer outside the substrate.
In one possible design, the causing the flame retardant in a molten state to enter at least one cell of a substrate having a plurality of cells includes:
uniformly mixing the flame retardant with the matrix;
allowing the mixture of the flame retardant and the substrate to stand at a first preset temperature for a first preset time;
the first preset temperature is greater than or equal to the melting point of the flame retardant and less than the boiling point of the flame retardant.
In another possible design, the mass ratio of the flame retardant to the substrate is (0.01-10): 1.
By controlling the mass ratio of the flame retardant to the substrate, the contact area of the substrate and the flame retardant in a molten state can be controlled, and the flame retardant can enter more pore channels.
In another possible design, the material of the protective layer is an organic polymer, and the forming of the protective layer outside the substrate includes:
and uniformly mixing the substrate filled with the flame retardant, an organic polymer monomer, a first solvent and an initiator for initiating the polymerization of the organic polymer monomer, and reacting for a second preset time to form the protective layer outside the substrate.
The organic polymer monomer is polymerized on the surface of the substrate under the action of an initiator to generate a corresponding organic polymer, so that an organic polymer protective layer is formed.
In another possible design, the initiator is selected from benzoyl peroxide, lauroyl peroxide, azobisisobutyronitrile, n-butyllithium, boron trifluoride, potassium persulfate, ammonium persulfate, or tin tetrachloride.
In another possible design, the mass ratio of the organic polymer monomer to the matrix filled with flame retardant is: (0.01-10) -1, wherein the mass ratio of the initiator to the organic polymer monomer is as follows: (0.1-10): 100.
In another possible design, after obtaining the flame retardant-filled substrate, before forming the protective layer outside the substrate, the preparation method further includes:
and removing the flame retardant which does not enter the pore channels of the substrate.
The performance of the secondary battery is prevented from being affected by removing the flame retardant that does not enter the pores of the substrate.
In a third aspect, embodiments of the present disclosure provide a septum, comprising:
a diaphragm body, a diaphragm cover and a diaphragm cover,
and a flame retardant layer disposed on at least one side surface of the separator body;
the flame retardant material of the first aspect of the embodiments of the present disclosure is dispersed in the flame retardant layer.
The flame-retardant material is loaded on the diaphragm, so that the flame-retardant material can play a role in flame retardance, can prevent the flame-retardant material from being aggregated and precipitated in electrolyte, and cannot influence the proceeding of electrode reactions on the positive electrode and the negative electrode.
In one possible design, the thickness of the membrane body is 6 to 20 microns and the thickness of the flame retardant layer is 0.4 to 4 microns.
In another possible design, on one side surface of the diaphragm body, the flame retardant layer covers an area of the diaphragm body in a proportion of 10% or more, or 20% or more, 30% or more, 40% or more, 50% or more, 60% or more, 70% or more, 80% or more, 90% or more, 100% or more of an area of the diaphragm body. When the area of the membrane body covered by the flame-retardant layer accounts for less than 100% of the area of the membrane body, the flame-retardant layer can comprise a plurality of sub flame-retardant layers, and a gap is formed between every two adjacent sub flame-retardant layers.
In another possible design, the distribution density of the flame retardant material on the membrane body is: 0.1 mg/cm to 10 mg/cm.
In another possible design, the material of the separator body is selected from at least one of polypropylene, polyethylene, polyester, polyimide, polyacrylonitrile, and glass fiber.
In a fourth aspect, an embodiment of the present disclosure provides a method for manufacturing a separator, including:
coating slurry containing the flame retardant material according to the first aspect of the embodiment of the present disclosure on at least one side surface of a separator body and drying the separator body coated with the slurry to form a flame retardant layer on at least one side surface of the separator body.
In one possible design, the slurry further includes: a second solvent, an emulsifier and an adhesive.
In another possible design, the second solvent is selected from at least one of N-methylpyrrolidone, dimethyl sulfoxide, N-dimethylformamide, and water.
In another possible design, the emulsifier is selected from at least one of polyvinyl alcohol, sodium polyacrylate, and polyacrylamide.
In another possible design, the adhesive is selected from at least one of polymethacrylic acid, polyvinylpyrrolidone, polyvinylidene fluoride, vinylidene fluoride-hexafluoropropylene copolymer, styrene butadiene rubber, and polymethylmethacrylate, polyacrylic acid.
In another possible design, in the slurry, the mass ratio of the flame-retardant material, the emulsifier, the adhesive and the second solvent is (0.8-1.2): (0.08-0.12): 0.18-0.22): 10.
In another possible design, the slurry is coated on the separator body to a thickness of 0.5 to 5 microns.
In another possible design, the drying the slurry coated separator body includes: and drying the diaphragm body coated with the slurry at 50-60 ℃.
In a fifth aspect, embodiments of the present disclosure provide a secondary battery including a positive electrode, a negative electrode, and a separator disposed between the positive electrode and the negative electrode, where the separator is the separator of the third aspect of the embodiments of the present disclosure.
In one possible design, the secondary battery is a lithium secondary battery.
The lithium secondary battery may be specifically a lithium ion battery using a lithium-containing compound (for example, lithium manganate, lithium nickel cobalt manganate, lithium phosphate, or the like) as a positive electrode and silicon or graphite as a negative electrode, or a lithium metal secondary battery using metal lithium as a negative electrode and sulfur or air as a positive electrode.
In a sixth aspect, embodiments of the present disclosure provide an electronic device including the secondary battery according to the fifth aspect of the embodiments of the present disclosure.
In the embodiments of the present disclosure, the electronic device includes, but is not limited to, a mobile phone, a tablet computer, a notebook computer, a digital camera, a bracelet, a watch, and the like.
The secondary battery provided by the embodiment of the disclosure can also be a secondary battery for a pure electric vehicle and a hybrid electric vehicle.
Drawings
FIG. 1 is a schematic structural diagram of a flame retardant material provided by an embodiment of the present disclosure;
FIG. 2 is a schematic view illustrating a flame retardant principle of a flame retardant material provided by an embodiment of the present disclosure;
FIG. 3 is a schematic flow chart of a method for preparing a flame retardant material according to an embodiment of the disclosure;
FIG. 4 is a schematic structural diagram of a diaphragm provided in an embodiment of the present disclosure;
fig. 5 is a schematic flow chart of a method for manufacturing a separator according to an embodiment of the present disclosure.
The reference numerals in the drawings denote:
10-a flame retardant material;
1-a substrate;
an X-channel;
2-a flame retardant;
3-a protective layer;
100-a membrane;
20-the body of the membrane.
Detailed Description
In order to make the technical solutions and advantages of the present disclosure clearer, the following will describe embodiments of the present disclosure in further detail with reference to the accompanying drawings. Unless defined otherwise, all technical terms used in the embodiments of the present disclosure have the same meaning as commonly understood by one of ordinary skill in the art.
Referring to fig. 1, a schematic structural diagram of a flame retardant material 10 according to an embodiment of the present disclosure is shown. As shown in fig. 1, the flame retardant material 10 includes:
a body 1 having a plurality of cells X,
a flame retardant 2 filled in at least one of the channels X of the matrix 1,
and a protective layer 3 covering the outside of the base 1.
In the flame retardant material provided by the embodiment of the disclosure, the flame retardant 2 is filled in the pore channel X of the substrate 1, and the protective layer 3 is coated outside the substrate 1, so that the flame retardant 2 can be effectively isolated from the external environment through the combined action of the pore channel structure of the substrate 1 and the protective layer 3. When the external environment temperature reaches the boiling point of the flame retardant 2, the flame retardant 2 is gasified and released to the external environment to play a flame retardant role. Based on this, the flame retardant material 10 provided by the embodiment of the disclosure is added to the secondary battery, when the secondary battery normally works, the flame retardant 2 is in a liquid state or a solid state, and under the combined action of the pore structure of the substrate 1 and the protective layer 3, the electrolyte can be effectively prevented from contacting the flame retardant 2, so that the flame retardant 2 is effectively prevented from entering the electrolyte and affecting the performance of the secondary battery when the secondary battery normally works. When the internal temperature of the secondary battery rises due to abuse and other factors and reaches the boiling point of the flame retardant 2, the flame retardant 2 is released to contact with the electrolyte, so that the flame retardant effect is achieved, and the secondary battery is prevented from burning. It can be seen that the flame retardant provided by the embodiments of the present disclosure can prevent the secondary battery from burning when the secondary battery is in an abusive state, and does not affect the performance of the secondary battery in a normal use state.
Meanwhile, for the flame retardant material in the related art, since the protective layer is directly coated outside the flame retardant 2, the flame retardant 2 can only be a flame retardant which is solid at normal temperature. In the flame retardant material 10 provided by the embodiment of the disclosure, a substrate for loading the flame retardant 2 is added, so that the flame retardant 2 in the flame retardant material 10 provided by the embodiment of the disclosure can be a liquid flame retardant at normal temperature, and the selection range of the flame retardant is expanded, so that the application range of the flame retardant material provided by the embodiment of the disclosure is wider.
It should be noted that the type of the flame retardant can be selected according to the actual use environment of the flame retardant material 10, for example, the flame retardant 2 is applied to a secondary battery, and the boiling point of the flame retardant 2 is not higher than the combustion temperature of the electrolyte, so as to ensure that the flame retardant 2 can be released in time to play a flame retardant role, thereby preventing the secondary battery from burning.
In the embodiment of the disclosure, the ratio of the number of the channels X filled with the flame retardant 2 in the base 1 to the total number of the channels X may be 10% or more, 20% or more, 30% or more, 40% or more, 50% or more, 60% or more, 70% or more, 80% or more, 90% or more, or 100%.
In the pore channel X filled with the flame retardant 2, the volume of the flame retardant 2 may account for 10% or more, 20% or more, 30% or more, 40% or more, 50% or more, 60% or more, 70% or more, 80% or more, 90% or more, or 100% of the volume of the pore channel X. In order to enable the flame retardant 2 to be released quickly when the external environment temperature reaches the boiling point of the flame retardant 2, the volume of the flame retardant accounts for less than 50% of the volume of the pore channel, and the flame retardant 2 is located at a position close to the opening of the pore channel.
It should be noted that the duct X has at least one opening, that is, at least one end of the two ends of the duct X is capable of communicating with the outside. For the cell X having two openings, which is filled with the flame retardant 2 at a position near each opening, the total volume of the flame retardant 2 accounts for 50% or less of the volume of the cell.
It can be understood that increasing the number of the channels X filled with the flame retardant 2, decreasing the amount of the flame retardant 2 filled in each channel X, and bringing the flame retardant 2 close to the opening of the channel X is advantageous for improving the flame retardant performance.
In the embodiment of the present disclosure, the shape of the substrate 1 may be prism (including but not limited to a quadrangular prism, a hexagonal prism, etc.), cylindrical or spherical; the plurality of channels X are parallel to each other and are all parallel to the axis of the base body 1. The plurality of pore canals can be communicated with each other or not. The diameter of the pore channel X may be 100 nm or less, for example, 100 nm, 90 nm, 80 nm, 70 nm, 60 nm, 50 nm, 40 nm, 30 nm, 20 nm, 10 nm, and the like.
In the embodiment of the disclosure, the mass ratio of the flame retardant 2 to the substrate 1 may be (0.01 to 10):1, for example, 0.01:1, 0.02:1, 0.04:1, 0.05:1, 0.06:1, 0.08:1, 0.1:1, 0.2:1, 0.4:1, 0.5:1, 0.6:1, 0.8:1, 0.9:1, 1:1, 2:1, 4:1, 5:1, 6:1, 8:1, 10:1, and the like.
The thickness of the protective layer 3 can be 0.01 microns to 10 microns, such as 0.01 microns, 0.02 microns, 0.04 microns, 0.05 microns, 0.06 microns, 0.08 microns, 0.1 microns, 0.2 microns, 0.4 microns, 0.6 microns, 0.8 microns, 1 micron, 1.5 microns, 2 microns, 2.5 microns, 3 microns, 3.5 microns, 4 microns, 4.5 microns, 5 microns, 5.5 microns, 6 microns, 6.5 microns, 7 microns, 7.5 microns, 8 microns, 8.5 microns, 9 microns, 9.5 microns, 10 microns, and the like.
In the embodiment of the present disclosure, a porous material such as a molecular sieve or a mesoporous material may be used as the substrate 1. The mesoporous material is a porous material with the pore diameter of 2-50 nanometers, and has the characteristics of large specific surface area, regular and ordered pore channels, narrow pore diameter distribution and the like. The mesoporous material is adopted, so that the flame retardant can be effectively adsorbed under the normal working state of the secondary battery, the flame retardant is prevented from entering electrolyte to influence the performance of the secondary battery, and after the internal temperature of the secondary battery rises to exceed the boiling point of the flame retardant 2 due to abuse and the like, the flame retardant 2 can be quickly released to prevent combustion.
The mesoporous material can be mesoporous carbon, mesoporous silica or mesoporous alumina. The mesoporous carbon may have a pore diameter of 2 nm to 10 nm (e.g., 2 nm, 3 nm, 4 nm, 5 nm, 6 nm, 7 nm, 8 nm, 9 nm, 10 nm, etc.), and a particle diameter of 200 nm to 2 μm (e.g., 200 nm, 400 nm, 500 nm, 600 nm, 800 nm, 1 μm, 1.2 μm, 1.4 μm, 1.5 μm, 1.6 μm, 1.8 μm, 2 μm, etc.).
In the embodiment of the present disclosure, the material of the protective layer 3 may be an organic polymer, an inorganic oxide, or a combination of the two. In the case of a protective layer containing inorganic oxides, the flame retardant 2 is vaporized and released through the protective layer. When the organic polymer and inorganic oxide composite protective layer 3 is used, the organic polymer layer may be located inside or outside the inorganic oxide layer.
For the organic polymer as the protective layer 3, the melting point of the organic polymer is usually lower than the boiling point of the flame retardant, so when the inside of the secondary battery is raised to reach the boiling point of the flame retardant 2, the organic polymer is melted, and the flame retardant 2 is directly released from the pore channel X of the substrate 1 to the external environment (as shown in fig. 2), which is beneficial to the rapid release of the flame retardant.
Inorganic oxides include, but are not limited to, silica.
Organic polymers include, but are not limited to, Polyvinylidene fluoride (PVDF), vinylidene fluoride-hexafluoropropylene copolymer (PVDF-HFP), Polymethyl methacrylate (PMMA), Polyacrylamide (PAM), Polyvinyl alcohol (PVA), Polyimide (Polyimide, PI), Polyethylene (PE), Polypropylene (PP), Polyacrylonitrile (PAN), Polyacrylic acid (PAA). One organic polymer may be used alone as the protective layer, or two or more organic polymers may be used to form a composite protective layer. For example, the substrate 1 may be coated with a polyethylene layer and then a polypropylene layer.
The organic polymer may have a weight average molecular weight of 1000 to 1000000, for example, 1000, 2000, 4000, 5000, 6000, 8000, 10000, 20000, 40000, 50000, 60000, 80000, 100000, 200000, 400000, 500000, 600000, 800000, 1000000, and the like.
In the disclosed embodiment, the flame retardant includes, but is not limited to, an organic phosphorus flame retardant, an inorganic phosphate flame retardant, a nitrogen-containing compound flame retardant, a halogen flame retardant, a silicon flame retardant, and the like, for example, triphenyl phosphate (TPP), trimethyl phosphate (TMP), triethyl phosphate (TEP), tributyl phosphate (TBP), trimethyl phosphite (TMPI), ammonium phosphate ((NH)4)3PO4) Ammonium sulfate ((NH)4)2SO4) Trimethyl acetamide (TMAC), triallyl cyanurate (TAC), fluoro carbonate, bromo carbonate, polysiloxane, silicone epoxy resin, and the like. One flame retardant can be used alone, or two or more flame retardants can be used in combination.
The following is a description of a method for preparing the flame retardant material provided in the embodiments of the present disclosure.
Referring to fig. 3, which is a schematic flow chart of a method for preparing a flame retardant material 10 according to an embodiment of the present disclosure, as shown in fig. 3, the method includes the following steps:
step S1, enabling the flame retardant 2 in a molten state to enter at least one pore channel X of the substrate 1 with a plurality of pore channels X to obtain the substrate 1 filled with the flame retardant;
in step S2, the protective layer 3 is formed outside the base 1.
In the preparation method provided by the embodiment of the disclosure, firstly, the flame retardant 2 in a molten state enters at least one pore channel X of the substrate 1 by utilizing the principle of capillary phenomenon to obtain the substrate 1 filled with the flame retardant, and then the protective layer 3 is formed outside the substrate 1, thereby obtaining the flame retardant material 10.
In one possible implementation manner of the embodiment of the present disclosure, in the step S1, the step of allowing the flame retardant 2 in a molten state to enter at least one pore channel X of the substrate 1 having a plurality of pore channels X includes the following steps:
step S11, uniformly mixing the flame retardant 2 with the substrate 1;
step S12, the mixture of the flame retardant 2 and the substrate 1 is left at the first preset temperature for a first preset time.
The first preset temperature is greater than or equal to the melting point of the flame retardant and less than the boiling point of the flame retardant.
The flame retardant 2 may be mixed with the base 1 and then placed in a tube furnace, and the temperature may be controlled by using the tube furnace. Protective gas such as nitrogen or argon can be introduced into the tube furnace to facilitate the flame retardant 2 to enter the pore channel X of the substrate 1.
The mass ratio of the flame retardant 2 to the substrate 1 may be (0.01 to 10):1, for example, 0.01:1, 0.02:1, 0.04:1, 0.05:1, 0.06:1, 0.08:1, 0.1:1, 0.2:1, 0.4:1, 0.5:1, 0.6:1, 0.8:1, 0.9:1, 1:1, 2:1, 4:1, 5:1, 6:1, 8:1, 10:1, or the like. The mass ratio of the flame retardant 1 to the substrate 2 and the volume of the substrate 1 can be controlled to increase the contact area between the substrate 1 and the flame retardant 2 in a molten state, so that the flame retardant 2 can enter more pore channels X.
The first preset time for which the mixture of the flame retardant 2 and the base 1 in a molten state is left to stand may be determined according to the amount of the flame retardant 2. When the using amount of the flame retardant 2 is less, the flame retardant can be placed for a shorter time; when the amount of the flame retardant 2 is large, it can be left for a long time. And, by controlling the first preset time, the amount of the flame retardant 2 filled in the single pore channel X of the substrate 1 and the position of the flame retardant 2 in the pore channel X can be controlled, and when the first preset time is shorter, the amount filled in the single pore channel X is smaller and is close to the opening of the pore channel X. For example, the first predetermined time may be 0.5 hours, 1 hour, 2 hours, 3 hours, 4 hours, 5 hours, 6 hours, or longer.
It should be noted that, after the flame retardant 2 in the molten state enters the pore X of the substrate 1, a step of reducing the temperature may be included to change the flame retardant 2 from the molten state to a solid state or a liquid state, so as to perform a subsequent step of forming the protective layer 3 on the exterior of the substrate 1.
As described above, the material of the protective layer 3 in the embodiment of the present disclosure may be an organic polymer, an inorganic oxide, or a combination of the two, and therefore, the specific implementation manner of the step S2 needs to be selected according to the specific kind of the protective layer 3.
For example, when the material of the protective layer 3 is silicon dioxide in inorganic oxide, the substrate 1 filled with the flame retardant may be uniformly mixed with tetraethoxysilane and water, and the tetraethoxysilane may undergo hydrolysis reaction on the surface of the substrate 1 to generate silicon dioxide, thereby forming a silicon dioxide protective layer outside the substrate 1.
When the material of the protective layer 3 is an organic polymer, the organic polymer protective layer may be formed in the following manner:
as an example of the present disclosure, the organic polymer protective layer may be formed by immersing the flame retardant-filled substrate 1 in a solution of an organic polymer, taking out the flame retardant-filled substrate 1, and removing the solvent.
As another example of the present disclosure, the flame retardant-filled substrate 1 may be uniformly mixed with an organic polymer monomer, a first solvent, and an initiator for initiating polymerization of the organic polymer monomer, and after reacting for a second predetermined time, an organic polymer protective layer may be formed outside the substrate 1.
In this example, the organic polymer monomer is polymerized on the surface of the substrate 1 by the initiator to form a corresponding organic polymer, thereby forming an organic polymer protective layer.
As described above, the organic polymer may be polyvinylidene fluoride, vinylidene fluoride-hexafluoropropylene copolymer, polymethyl methacrylate, polyacrylamide, polyvinyl alcohol, polyimide, polyethylene, polypropylene, polyacrylonitrile, polyacrylic acid, or the like, and the organic polymer monomer may be vinylidene fluoride, a combination of vinylidene fluoride and hexafluoropropylene, methyl methacrylate, acrylamide, vinyl acetate, a combination of diamine and dibasic acid (or dibasic anhydride), ethylene, propylene, acrylonitrile, acrylic acid, or the like.
The vinyl acetate is a monomer of polyvinyl alcohol, the vinyl acetate is firstly polymerized to form a polyvinyl acetate protective layer, and the polyvinyl acetate protective layer is obtained after alcoholysis is carried out on the polyvinyl acetate.
Initiators include, but are not limited to, Benzoyl Peroxide (BPO), Lauroyl Peroxide (LPO), Azobisisobutyronitrile (AIBN), n-Butyllithium (C)4H9Li), boron trifluoride (BF)3) Potassium persulfate (K)2S2O8) Ammonium persulfate ((NH)4)2S2O8) Or tin tetrachloride (SnCl)4) And the like. Suitable initiators may be selected depending on the nature of the organic polymer monomer. For example, benzoyl peroxide and azobisisobutyronitrile are freeRadical polymerization initiators which can be used to initiate monomers suitable for radical polymerization such as ethylene, methyl methacrylate, acrylic acid, etc.; n-butyllithium is an anionic polymerization initiator and can be used to initiate monomers suitable for anionic polymerization, such as acrylonitrile.
The first solvent may be selected according to the properties of the organic polymer monomer and the initiator, and may be water, or organic solvents such as methanol, ethanol, acetone, tetrahydrofuran, n-hexane, and the like.
In the embodiment of the disclosure, the mass ratio of the organic polymer monomer to the matrix filled with the flame retardant may be: (0.01 to 10) to 1, for example, 0.01:1, 0.02:1, 0.04:1, 0.05:1, 0.06:1, 0.08:1, 0.1:1, 0.2:1, 0.4:1, 0.5:1, 0.6:1, 0.8:1, 0.9:1, 1:1, 2:1, 4:1, 5:1, 6:1, 8:1, 10:1, etc. The thickness of the formed protective layer 3 is controlled by controlling the mass ratio of the organic polymer monomer and the matrix filled with the flame retardant.
The mass ratio of the initiator to the organic polymer monomer may be: (0.1-10): 100, for example, 0.1:100, 0.2:100, 0.4:100, 0.5:100, 0.6:100, 0.8:100, 1:100, 2:100, 4:100, 5:100, 6:100, 8:100, 10:100, etc., and the molecular weight of the organic polymer is controlled by controlling the mass ratio of the initiator to the organic polymer monomer.
Further, in the preparation method of the flame retardant material provided by the embodiment of the present disclosure, in the process of making the flame retardant in a molten state enter the pore channel X of the base body 1, due to the limitation of technical conditions, the flame retardant 2 may be attached to the outer surface of the base body 1, and when the method is applied to a secondary battery, the flame retardant attached to the outer surface of the base body 1 may easily enter the electrolyte to affect the performance of the secondary battery. Therefore, before forming the protective layer 3 on the outside of the base body 1, a step of removing the flame retardant 2 that does not enter the cell channels X of the base body 1 may be further included. For example, the flame retardant 2 that does not enter the pores X of the substrate 1 may be removed by performing a gas purge at a second predetermined temperature. The second predetermined temperature may be higher than the first predetermined temperature.
When the flame retardant material 10 provided by the embodiment of the present disclosure is applied to a secondary battery, the flame retardant material 10 may be added to an electrolyte, or may be supported on a positive electrode, a negative electrode, or a separator. The flame retardant material 10 is loaded on the diaphragm, so that the flame retardant material 10 can be prevented from being aggregated and precipitated in the electrolyte, and the electrode reaction on the positive electrode and the negative electrode can not be influenced. Based on this, the embodiment of the present disclosure provides a diaphragm based on the flame retardant material 10 and a preparation method of the diaphragm.
Hereinafter, a separator provided in an embodiment of the present disclosure will be described in detail.
Referring to fig. 4, which is a schematic structural diagram of a diaphragm 100 according to an embodiment of the present disclosure, as shown in fig. 4, the diaphragm 100 includes:
the body of the septum 20 is shown as being,
and a flame retardant layer disposed on at least one side surface of the separator body 20.
Wherein the flame retardant material 10 is dispersed in the flame retardant layer.
The diaphragm 100 provided by the embodiment of the disclosure is arranged in the secondary battery, and when the secondary battery normally works, under the combined action of the pore structure of the substrate 1 and the protective layer 3, the electrolyte can be effectively prevented from contacting with the flame retardant, so that the flame retardant is effectively prevented from entering the electrolyte and influencing the performance of the secondary battery when the secondary battery normally works. When the internal temperature of the secondary battery rises due to abuse and other factors and reaches the boiling point of the flame retardant 2, the flame retardant 2 is released to contact with the electrolyte, so that the flame retardant effect is achieved, and the secondary battery is prevented from burning.
In embodiments of the present disclosure, the thickness of the septum body 20 may be 6 microns to 20 microns, such as 6 microns, 7 microns, 8 microns, 9 microns, 10 microns, 11 microns, 12 microns, 13 microns, 14 microns, 15 microns, 16 microns, 17 microns, 18 microns, 19 microns, 20 microns, and the like.
The thickness of the flame retardant layer can be 0.4 microns to 4 microns, such as 0.4 microns, 0.5 microns, 0.6 microns, 0.7 microns, 0.8 microns, 0.9 microns, 1 micron, 1.5 microns, 2 microns, 2.5 microns, 3 microns, 3.5 microns, 4 microns, and the like.
The distribution density of the flame retardant material 10 on the membrane body 20 may be: 0.1 mg/cm to 10 mg/cm, for example, 0.1 mg/cm, 0.2 mg/cm, 0.4 mg/cm, 0.5 mg/cm, 0.6 mg/cm, 0.8 mg/cm, 1 mg/cm, 1.5 mg/cm, 2 mg/cm, 2.5 mg/cm, 3 mg/cm, 3.5 mg/cm, 4 mg/cm, 4.5 mg/cm, 5 mg/cm, 5.5 mg/cm, 6 mg/cm, 6.5 mg/cm, 7 mg/cm, 7.5 mg/cm, 8 mg/cm, 8.5 mg/cm, 9 mg/cm, 9.5 mg/cm, 10 mg/cm, etc.
In the embodiment of the present disclosure, on one side surface of the separator body 20, the proportion of the area of the flame retardant layer covering the separator body 20 to the area of the separator body may be 10% or more, 20% or more, 30% or more, 40% or more, 50% or more, 60% or more, 70% or more, 80% or more, 90% or more, or 100% or the like. When the area of the flame-retardant layer covering the diaphragm body 20 accounts for less than 100% of the area of the diaphragm body, the flame-retardant layer may include a plurality of sub flame-retardant layers, and a gap is formed between two adjacent sub flame-retardant layers.
The material of the separator body 20 is not particularly limited in the embodiments of the present disclosure, and the material of the separator commonly used in the secondary battery may include, but is not limited to, at least one of polypropylene, Polyethylene, Polyester (PET), polyimide, polyacrylonitrile, and glass fiber.
The following is a description of a method for manufacturing the separator provided in the embodiments of the present disclosure.
Referring to fig. 5, which is a schematic flow chart of a method for manufacturing the separator 100 according to an embodiment of the present disclosure. As shown in fig. 5, the preparation method includes: a slurry containing the above flame retardant material 10 is coated on at least one side surface of the separator body 20 and the separator body 20 coated with the slurry is dried, forming a flame retardant layer on at least one side surface of the separator body 20.
Wherein, besides the flame retardant material 10, the slurry can also comprise: a second solvent, an emulsifier and an adhesive. The second solvent is used for dispersing the flame-retardant material 10, the adhesive is used for bonding the flame-retardant material 10 to the surface of the diaphragm body 20, and the emulsifier is used for enabling the flame-retardant material 10 and the adhesive to be uniformly dispersed in the second solvent.
The second solvent includes, but is not limited to, at least one of N-methylpyrrolidone (1-Methyl-2-pyrrolidone, NMP), Dimethyl sulfoxide (DMSO), N-Dimethylformamide (DMF), and water.
The emulsifier includes, but is not limited to, at least one of polyvinyl alcohol, Sodium polyacrylate (Sodium polyacrylate), and polyacrylamide.
The adhesive includes, but is not limited to, polymethacrylic acid (PMAA), polyvinylpyrrolidone (PVP), polyvinylidene fluoride, vinylidene fluoride-hexafluoropropylene copolymer, Styrene Butadiene Rubber (SBR), and at least one of polymethyl methacrylate and polyacrylic acid.
In the embodiment of the disclosure, the mass ratio of the flame-retardant material 10, the emulsifier, the adhesive and the second solvent in the slurry may be (0.8-1.2): (0.08-0.12): (0.18-0.22): 10, for example, 0.8:0.08:0.18:10, 1:0.1:0.2:10, 1.2:0.12:2.2:10, 0.1:0.08:0.18:10, 0.8:0.1:0.2:10, 0.9:0.09:0.18:10, etc
The slurry may be coated on separator body 20 to a thickness of 0.5 microns to 5 microns, such as 0.5 microns, 0.6 microns, 0.7 microns, 0.8 microns, 0.9 microns, 1 micron, 2 microns, 3 microns, 4 microns, 5 microns, and the like. The slurry may be coated on the separator body 20 by means of a doctor blade.
In the embodiment of the present disclosure, the specific steps of drying the diaphragm body coated with the slurry may be: the drying is performed at 50 to 60 degrees celsius (e.g., 52, 54, 55, 56, 58, 60 degrees celsius, etc.). The drying time is not strictly limited, so that the second solvent in the slurry can be completely removed.
Based on the separator, the disclosed embodiments provide a secondary battery. The secondary battery comprises a positive electrode, a negative electrode and a separator arranged between the positive electrode and the negative electrode, wherein the separator is the separator 100.
In the disclosed embodiments, the secondary battery includes, but is not limited to, a lithium secondary battery. The lithium secondary battery may be a lithium ion battery in which a lithium-containing compound (e.g., lithium manganate, lithium nickel cobalt manganate, lithium phosphate, etc.) is used as a positive electrode and silicon or graphite is used as a negative electrode, or a lithium metal secondary battery in which metal lithium is used as a negative electrode and sulfur or air is used as a positive electrode.
Based on the secondary battery, the embodiment of the present disclosure provides an electronic device including the secondary battery.
In the embodiments of the present disclosure, the electronic device includes, but is not limited to, a mobile phone, a tablet computer, a notebook computer, a digital camera, a bracelet, a watch, and the like.
The secondary battery provided by the embodiment of the disclosure can also be a secondary battery for a pure electric vehicle or a hybrid electric vehicle.
The technical solution of the embodiments of the present disclosure will be described in further detail below by taking mesoporous carbon as an example of the substrate.
The mesoporous carbon used in the following examples is a type CMK-3 mesoporous carbon.
The performance parameters of the mesoporous carbon with the model of CMK-3 are shown in Table 1:
TABLE 1CMK-3 type mesoporous carbon Performance parameters
In table 1, micropores refer to pores having a pore diameter of less than 2 nm.
In the following examples, those whose operations are not subject to the conditions are carried out according to the conventional conditions or conditions recommended by the manufacturer. The raw materials are conventional products which can be obtained commercially by manufacturers and specifications.
In the following examples, the composition of the flame retardant material is represented in the form a @ B @ C, wherein a represents a substrate, B represents a flame retardant, and C represents a protective layer.
Example 1
The embodiment provides a mesoporous carbon @ trimethyl phosphate @ polymethyl methacrylate flame retardant material and a polypropylene diaphragm based on the flame retardant material.
The preparation method of the mesoporous carbon @ trimethyl phosphate @ polymethyl methacrylate flame-retardant material comprises the following steps:
1. preparation of mesoporous carbon loaded with trimethyl phosphate
1) 0.5g of trimethyl phosphate and 1.5g of mesoporous carbon were first mixed and ground to give a mixture, which was placed in a tube furnace and an argon atmosphere was passed through.
2) And then, raising the temperature in the tubular furnace to 40 ℃ and preserving the temperature for 5h to ensure that trimethyl phosphate enters a pore channel of the mesoporous carbon through melting and diffusion under the capillary action of the mesoporous carbon.
3) And then heating to 120 ℃, preserving the heat for 20 minutes, and removing trimethyl phosphate which does not enter the pore channels of the mesoporous carbon.
4) Cooling to obtain the mesoporous carbon loaded with trimethyl phosphate.
2. Preparation of mesoporous carbon @ trimethyl phosphate @ polymethyl methacrylate flame-retardant material
1g of the mesoporous carbon loaded with trimethyl phosphate and 1g of Methyl Methacrylate (MMA) are added into 48g of water, 0.1g of azobisisobutyronitrile is added into the water, and the mixture is mechanically stirred at room temperature for 5 hours to polymerize the Methyl methacrylate on the surface of the mesoporous carbon, so that the mesoporous carbon @ trimethyl phosphate @ polymethyl methacrylate flame retardant material of the embodiment is obtained.
The preparation method of the polypropylene separator provided in this example is as follows:
1g of the mesoporous carbon @ trimethyl phosphate @ polymethyl methacrylate flame retardant material of the embodiment was dispersed in 10g of water, and then 0.1g of polyvinyl alcohol and 0.2g of polyacrylic acid were added to the water, and the mixture was stirred uniformly to obtain a slurry.
The resulting slurry was knife-coated with a squeegee on both side surfaces of a polypropylene separator having a thickness of 10 μm and the polypropylene separator coated with the slurry having a coating thickness of 2 μm was dried at 50 ℃.
Example 2
The embodiment provides a mesoporous carbon @ triphenyl phosphate @ polymethyl methacrylate flame retardant material and a polypropylene diaphragm based on the flame retardant material.
The preparation method of the mesoporous carbon @ triphenyl phosphate @ polymethyl methacrylate flame retardant material comprises the following steps:
1. preparation of triphenyl phosphate-loaded mesoporous carbon
1) 0.5g of triphenyl phosphate and 1.5g of mesoporous carbon were first mixed and ground to give a mixture, which was placed in a tube furnace and an argon atmosphere was passed through.
2) And then, raising the temperature in the tube furnace to 60 ℃ and preserving the temperature for 5h, so that the triphenyl phosphate enters the pore channel of the mesoporous carbon through melting and diffusion under the capillary action of the mesoporous carbon.
3) And then heating to 130 ℃, preserving the heat for 20 minutes, and removing triphenyl phosphate which does not enter the pore channels of the mesoporous carbon.
4) Cooling to obtain the mesoporous carbon loaded with triphenyl phosphate.
2. Preparation of mesoporous carbon @ triphenyl phosphate @ polymethyl methacrylate flame-retardant material
1g of the above-mentioned mesoporous carbon supporting triphenyl phosphate and 1g of Methyl Methacrylate (MMA) were added to 48g of water, 0.1g of azobisisobutyronitrile was added to the water, and the mixture was mechanically stirred at room temperature for 5 hours to polymerize Methyl methacrylate on the surface of the mesoporous carbon, thereby obtaining the mesoporous carbon @ triphenyl phosphate @ polymethyl methacrylate flame retardant material of this example.
The preparation method of the polypropylene separator provided in this example is as follows:
1g of the mesoporous carbon @ triphenyl phosphate @ polymethyl methacrylate flame retardant material of the embodiment is dispersed in 10g of water, then 0.1g of polyvinyl alcohol and 0.2g of polyacrylic acid are added into the water, and the mixture is stirred uniformly to obtain slurry.
The resulting slurry was knife-coated with a squeegee on both side surfaces of a polypropylene separator having a thickness of 10 μm and the polypropylene separator coated with the slurry having a coating thickness of 2 μm was dried at 55 ℃.
Example 3
The embodiment provides a mesoporous carbon @ triphenyl phosphate @ polyacrylamide flame retardant material and a polypropylene diaphragm based on the flame retardant material.
The preparation method of the mesoporous carbon @ triphenyl phosphate @ polyacrylamide flame retardant material comprises the following steps:
1. preparation of triphenyl phosphate-loaded mesoporous carbon
1) 0.5g of triphenyl phosphate and 1.5g of mesoporous carbon were first mixed and ground to give a mixture, which was placed in a tube furnace and an argon atmosphere was passed through.
2) And then, raising the temperature in the tube furnace to 60 ℃ and preserving the temperature for 5h, so that the triphenyl phosphate enters the pore channel of the mesoporous carbon through melting and diffusion under the capillary action of the mesoporous carbon.
3) And then heating to 130 ℃, preserving the heat for 20 minutes, and removing triphenyl phosphate which does not enter the pore channels of the mesoporous carbon.
4) Cooling to obtain the mesoporous carbon loaded with triphenyl phosphate.
2. Preparation of mesoporous carbon @ triphenyl phosphate @ polyacrylamide flame-retardant material
1g of the above mesoporous carbon loaded with triphenyl phosphate and 1g of Acrylamide (AM) were added to 48g of water, and then 0.1g of azobisisobutyronitrile was added to the water, and mechanically stirred at room temperature for 5 hours, so that Acrylamide was polymerized on the surface of the mesoporous carbon, thereby obtaining the mesoporous carbon @ triphenyl phosphate @ polyacrylamide flame retardant material of this example.
The preparation method of the polypropylene separator provided in this example is as follows:
1g of the mesoporous carbon @ triphenyl phosphate @ polyacrylamide flame retardant material of the embodiment is dispersed in 10g of water, then 0.1g of polyvinyl alcohol and 0.2g of polyacrylic acid are added into the water, and the mixture is stirred uniformly to obtain slurry.
The resulting slurry was knife-coated with a squeegee on both side surfaces of a polypropylene separator having a thickness of 10 μm and the polypropylene separator coated with the slurry was dried at 60 degrees celsius to a coating thickness of 2 μm.
Example 4
In this embodiment, the separators provided in the above embodiments 1 to 3 are assembled into a lithium ion battery, the cycle performance of the obtained lithium ion battery is tested, the flame resistance of the obtained lithium ion battery is tested by a needle punching experiment (tail networking), and a common polypropylene separator is used as a comparison.
The Lithium ion battery is a soft package battery with the volume ratio of about 3.7Ah, the positive electrode is commercial Lithium cobaltate, the negative electrode is commercial graphite, and the electrolyte is 1mol/L Lithium Hexafluorophosphate (LiPF) with the volume ratio of 1:1:1:16) Ethylene Carbonate (EC) solution + polycarbonate (Propylene carbonate, PC) + diethyl carbonate (diethyl carbonate, DEC) + Ethyl Methyl Carbonate (EMC).
The test conditions of the cycle performance of the lithium ion battery are as follows: 25 ℃; 3.0-4.4V; 0.7C charge/0.7C discharge.
The needling test conditions are as follows: in a fully charged state of the lithium ion battery, a steel needle having a diameter of 5mm was inserted into the lithium ion battery at a speed of 10 mm/s.
100 battery samples were prepared from the separators provided in examples 1 to 3 and a common polypropylene separator, respectively.
The cycle performance and the results of the needling test are shown in Table 2.
TABLE 2 test results
As can be seen from the data in table 2:
1) compared with the common diaphragm, the diaphragm provided by the embodiment of the disclosure has a good flame retardant effect, and under the dual actions of the mesoporous carbon and the organic polymer protective layer, the addition of the flame retardant material does not cause obvious influence on the cycle performance of the lithium ion battery.
2) As can be seen from comparison of the data of example 1 and example 2, the flame retardant material in which the flame retardant is triphenyl phosphate has a better flame retardant effect than the flame retardant material in which the flame retardant is trimethyl phosphate.
3) As can be seen from the comparison of the data in example 2 and example 3, compared with the polyacrylamide protective layer, the polymethyl methacrylate protective layer has better protective effect, and the influence of the polymethyl methacrylate as the flame retardant material of the protective layer on the battery performance is smaller.
In summary, the flame retardant material and the diaphragm based on the flame retardant material provided by the embodiment of the disclosure can ensure the performance of the secondary battery in a normal working state on one hand and ensure the safety of the secondary battery on the other hand. In addition, the preparation method of the flame-retardant material and the diaphragm provided by the embodiment of the disclosure is simple, easy to control, suitable for large-scale industrial production and wide in application prospect.
The above description is only for facilitating the understanding of the technical solutions of the present disclosure by those skilled in the art, and is not intended to limit the present disclosure. Any modification, equivalent replacement, improvement and the like made within the spirit and principle of the present disclosure should be included in the protection scope of the present disclosure.
Claims (16)
1. A fire retardant material, comprising:
a substrate having a plurality of cells therein,
a flame retardant filled in at least one of the channels of the substrate,
the protective layer is coated outside the substrate and consists of an organic polymer layer and an inorganic oxide layer, and the organic polymer layer is positioned on the outer side or the inner side of the inorganic oxide layer;
in the pore channel filled with the flame retardant, the volume of the flame retardant accounts for more than 10% and less than 50% of the volume of the pore channel, and the flame retardant is positioned at the position close to the opening of the pore channel.
2. The flame retardant material according to claim 1, wherein the proportion of the number of the cells filled with the flame retardant in the matrix to the total number of the cells is 10% or more.
3. The flame retardant material of any one of claims 1 to 2 wherein the matrix has a prismatic, cylindrical or spherical shape; the pore channels are parallel to each other and are parallel to the axis of the base body.
4. Flame retardant material according to claim 1 or 2, characterized in that the material of the matrix is a mesoporous material.
5. The flame retardant material of claim 4 wherein the material of the matrix is mesoporous carbon, mesoporous silica or mesoporous alumina.
6. The preparation method of the flame retardant material is characterized by comprising the following steps of:
enabling a flame retardant in a molten state to enter at least one pore channel of a substrate with a plurality of pore channels by a capillary phenomenon principle, enabling the volume of the flame retardant in each pore channel of the at least one pore channel to be more than 10% and less than 50%, and enabling the flame retardant to be located at a position close to an opening of the pore channel to obtain the substrate filled with the flame retardant;
and forming a protective layer outside the substrate, wherein the protective layer is composed of an organic polymer layer and an inorganic oxide layer, and the organic polymer layer is positioned at the outer side or the inner side of the inorganic oxide layer.
7. The method for preparing a flame retardant material according to claim 6, wherein the step of introducing the flame retardant in a molten state into at least one cell of a substrate having a plurality of cells comprises:
uniformly mixing the flame retardant with the matrix;
allowing the mixture of the flame retardant and the substrate to stand at a first preset temperature for a first preset time;
the first preset temperature is greater than or equal to the melting point of the flame retardant and less than the boiling point of the flame retardant.
8. The method for preparing the flame retardant material according to any one of claims 6 to 7, wherein after obtaining the flame retardant filled substrate, before forming the protective layer on the outside of the substrate, the method further comprises:
and removing the flame retardant which does not enter the pore channels of the substrate.
9. A septum, comprising:
a diaphragm body, a diaphragm cover and a diaphragm cover,
and a flame retardant layer disposed on at least one side surface of the separator body;
a flame retardant material as claimed in any one of claims 1 to 5 dispersed in said flame retardant layer.
10. The membrane of claim 9, wherein the flame retardant material is distributed on the membrane body at a density of: 0.1 mg/cm to 10 mg/cm.
11. A method of making a separator, comprising:
coating a slurry containing the flame retardant material according to any one of claims 1 to 5 on at least one side surface of a separator body and drying the separator body coated with the slurry to form a flame retardant layer on at least one side surface of the separator body.
12. The method for producing a separator according to claim 11, wherein the slurry further comprises: a second solvent, an emulsifier and an adhesive.
13. The method for producing a separator according to claim 12, wherein the second solvent is at least one selected from the group consisting of N-methylpyrrolidone, dimethylsulfoxide, N-dimethylformamide, and water;
the emulsifier is at least one selected from polyvinyl alcohol, sodium polyacrylate and polyacrylamide;
the adhesive is selected from at least one of polymethacrylic acid, polyvinylpyrrolidone, polyvinylidene fluoride, vinylidene fluoride-hexafluoropropylene copolymer, styrene butadiene rubber, polymethyl methacrylate and polyacrylic acid.
14. A secondary battery comprising a positive electrode, a negative electrode, and a separator provided between the positive electrode and the negative electrode, characterized in that the separator is the separator according to claim 9 or 10.
15. The secondary battery according to claim 14, wherein the secondary battery is a lithium secondary battery.
16. An electronic device characterized in that the electronic device comprises the secondary battery according to claim 14 or 15.
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| CN111933879A (en) * | 2020-07-21 | 2020-11-13 | 清华大学 | Lithium ion battery |
| CN112382829B (en) * | 2020-10-14 | 2023-01-17 | 江西银汇新能源有限公司 | Functional flexible membrane and preparation method and application thereof |
| CN115139614B (en) * | 2022-07-26 | 2024-02-06 | 浙江龙财塑业有限公司 | Modified polypropylene power conduit and preparation method thereof |
| CN115621660B (en) * | 2022-09-08 | 2023-05-09 | 阜阳隆能科技有限公司 | Composite diaphragm for lithium battery cell, lithium battery cell and lithium battery |
| CN115863893B (en) * | 2023-01-31 | 2023-07-18 | 荣耀终端有限公司 | Terminal device |
| CN116435712B (en) * | 2023-06-09 | 2023-08-11 | 苏州精控能源科技有限公司 | Reinforced modified coating for lithium battery diaphragm, preparation method thereof and lithium battery diaphragm |
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| US9719019B1 (en) * | 2006-10-30 | 2017-08-01 | Alan M. Gilbert | Flame-retardant materials and systems |
| CN106876638A (en) * | 2015-12-13 | 2017-06-20 | 中国科学院大连化学物理研究所 | A kind of flow battery molecular sieve composite porous film and its preparation and application |
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