Diaphragm, preparation method thereof and battery

Abstract

The invention relates to the field of batteries, in particular to a diaphragm, a preparation method thereof and a battery. The diaphragm comprises a base membrane and a coating arranged on the base membrane, the coating comprises a metal organic framework material and a gel electrolyte; the gel electrolyte includes a random copolymer comprising a first polymer and a second polymer; polymeric monomers of the first polymer comprise an acrylate monomer and an acrylamide monomer; polymeric monomers of the second polymer include glycidyl ether monomers. The preparation method of the diaphragm comprises the following steps: carrying out polymerization reaction on an acrylate monomer and an acrylamide monomer to obtain an intermediate; and carrying out polymerization reaction on the intermediate and a glycidyl ether monomer to obtain the gel electrolyte, mixing a gel electrolyte, a metal organic framework material and a solvent to obtain slurry; and coating a base membrane with the slurry to obtain the diaphragm. The diaphragm provided by the invention does not contain fluorine atoms in main components, is pollution-free, can adsorb metal ions, and improves the electrolyte storage capability and the desolvation capability.

Description

Technical Field

[0001] The present invention relates to the field of batteries, and in particular to a diaphragm and a preparation method thereof, and a battery. Background Art

[0002] As an important component of lithium batteries, the diaphragm is of great significance for blocking electrons to prevent short circuits and ensure internal ion permeation so that the battery can operate efficiently, stably and safely. Although the diaphragm itself does not undergo any electrochemical reaction, its structure and performance affect the interface structure and internal resistance of the battery, and thus affect the overall capacity, charge and discharge current density, cycle performance and safety of the battery. Therefore, through the analysis, testing and regulation of various performance parameters of lithium battery diaphragms, the comprehensive performance of the battery can be effectively improved.

[0003] The wettability and wetting speed of the separator are of great significance to the operation of lithium-ion batteries. By selecting a suitable base membrane and coating the surface of the base membrane with different functional coatings, different effects can be achieved in the battery cell. The most widely used coating material is PVDF (polyvinylidene fluoride). Since PVDF contains fluorine elements, the presence of a large amount of PVDF in the coating material will cause irreversible damage to the environment. In addition, PVDF has limited liquid absorption and liquid retention capacity, and does not have the ability to adsorb and lock ions. Summary of the invention

[0004] In view of this, the present invention is committed to providing a diaphragm and a preparation method thereof and a battery, wherein the main component of the diaphragm does not contain fluorine atoms and is pollution-free, and can adsorb metal ions, thereby improving the ability to preserve electrolytes and the desolvation ability.

[0005] In order to solve the above technical problems, this application is implemented as follows:

[0006] According to a first aspect of the present invention, the present invention provides a diaphragm, the diaphragm comprising a base film and a coating disposed on at least one surface of the base film in a thickness direction;

[0007] The coating comprises a metal organic framework material and a gel electrolyte;

[0008] The gel electrolyte comprises: a random copolymer including a first polymer and a second polymer;

[0009] Wherein, the polymerization monomers of the first polymer include acrylate monomers and acrylamide monomers;

[0010] The polymerization monomers of the second polymer include glycidyl ether monomers.

[0011] In any embodiment, the mass ratio of the metal organic framework material to the gel electrolyte is (15-40): (3-10).

[0012] In any embodiment, the coating further comprises a binder and a dispersant.

[0013] In any embodiment, the mass ratio of the metal organic framework material, the gel electrolyte, the binder and the dispersant is (15-40): (3-10): (1-5): (0.5-3).

[0014] In any embodiment, the binder includes at least one of polyvinylidene fluoride, carboxymethyl cellulose, or polyacrylic acid.

[0015] In any embodiment, the dispersant includes at least one of a cationic polymer dispersant, polyethylene, polypropylene, or polystyrene.

[0016] In any embodiment, the mass ratio of the acrylate monomer to the acrylamide monomer is (1.2-3):1.

[0017] In any embodiment, the mass ratio of the acrylic acid ester monomer to the glycidyl ether monomer is (60-90):(10-20).

[0018] In any embodiment, the acrylic acid ester monomer includes at least one of methyl methacrylate, methyl acrylate, ethyl acrylate, n-butyl acrylate, and ethyl methacrylate.

[0019] In any embodiment, the acrylamide monomer includes at least one of N-isopropylacrylamide, acrylamide or N,N-dimethylacrylamide.

[0020] In any embodiment, the glycidyl ether monomer includes at least one of neopentyl glycol diglycidyl ether, 1,4-butanediol diglycidyl ether, ethylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether or 1,6-hexanediol diglycidyl ether.

[0021] In any embodiment, the base film has a thickness of 5 to 10 μm.

[0022] In any embodiment, the coating has a thickness of 3 to 6 μm.

[0023] According to a second aspect of the present invention, the present invention provides a method for preparing a diaphragm, comprising the following steps:

[0024] The acrylate monomer and the acrylamide monomer are subjected to a first polymerization reaction to obtain an intermediate; the intermediate and the glycidyl ether monomer are subjected to a second polymerization reaction to obtain a gel electrolyte;

[0025] Mixing the gel electrolyte, the metal organic framework material and the first solvent to obtain a slurry;

[0026] The slurry is applied on at least one surface of the base film along the thickness direction to obtain a separator.

[0027] In any embodiment, the process of the first polymerization reaction comprises:

[0028] The acrylate monomer, the acrylamide monomer, the first initiator and the second solvent are mixed and subjected to a first polymerization reaction to obtain an intermediate.

[0029] In any embodiment, the second polymerization process comprises:

[0030] The intermediate solution, the glycidyl ether monomer solution and the second initiator are mixed to carry out a second polymerization reaction to obtain a gel electrolyte.

[0031] In any embodiment, the mass ratio of the acrylic acid ester monomer to the acrylamide monomer is (1.2-3):1;

[0032] In any embodiment, the mass ratio of the intermediate solution to the glycidyl ether monomer solution is (4-12):1.

[0033] In any embodiment, the concentration of the intermediate in the intermediate solution is 8 to 12 wt %.

[0034] In any embodiment, the concentration of the glycidyl ether monomer solution is 0.5-1.2 wt %.

[0035] In any embodiment, the solvent in the intermediate solution comprises water.

[0036] In any embodiment, the solvent in the glycidyl ether monomer solution includes water.

[0037] In any embodiment, the temperature of the first polymerization is 20 to 45° C., and the time of the first polymerization is 3 to 7 hours.

[0038] In any embodiment, the temperature of the second polymerization reaction is 20 to 45° C., and the time of the second polymerization is 2 to 4 hours.

[0039] In any embodiment, after the second polymerization reaction is completed, a post-treatment is further included.

[0040] The post-treatment comprises: after the second polymerization reaction is completed, heating the obtained product and then sieving it to obtain a gel electrolyte.

[0041] In any embodiment, the temperature of the heating treatment is 18 to 35° C., and the time of the heating treatment is 2 to 4 hours.

[0042] In any embodiment, the sieve has a mesh size of 200 to 300 meshes.

[0043] In any embodiment, the first solvent comprises water.

[0044] In any embodiment, the slurry further includes a binder and a dispersant.

[0045] In any embodiment, the binder includes at least one of polyvinylidene fluoride, carboxymethyl cellulose, or polyacrylic acid.

[0046] In any embodiment, the dispersant includes at least one of a cationic polymer dispersant, polyethylene, polypropylene, or polystyrene.

[0047] According to a third aspect of the present invention, the present invention provides a battery, wherein the battery comprises the above-mentioned separator or the separator produced by the above-mentioned method.

[0048] Through the above technical solution, the beneficial technical effects of the present invention are:

[0049] In an embodiment of the present application, the provided diaphragm and its preparation method are mainly composed of a membrane and a coating arranged on the surface of at least one side of the base membrane along the thickness direction, and the coating includes a metal organic framework material and a gel electrolyte; wherein the gel electrolyte includes a random copolymer comprising a first polymer and a second polymer; the polymerization monomers of the first polymer include acrylate monomers and acrylamide monomers; the polymerization monomers of the second polymer include glycidyl ether monomers. After the coating in the diaphragm is immersed in the electrolyte, the gel electrolyte in the coating will absorb the electrolyte and become a gel, thereby improving the interface contact between the diaphragm and the electrolyte, thereby enhancing the ion transmission capacity of the diaphragm in the battery cell, thereby reducing the internal resistance and effectively improving the cycle performance of the battery cell; at the same time, the absorption of electrolyte by the gel electrolyte can also reduce battery leakage and improve the safety performance of the battery cell; the metal organic framework material has a high porosity and excellent chemical stability, and the gel electrolyte and the metal organic framework material are used in combination to capture Ni 2+ , Cu 2+ , Fe 3+ , Mn 2+ 、Co 2+ Metal ions such as fluorine can enhance the capacity and desolvation ability of the electrolyte, achieving the effect of 1+1>2. In addition, the gel electrolyte is obtained by polymerization of acrylate monomers, acrylamide monomers and glycidyl ether monomers. There is no fluorine element in the raw materials, so the main components of the final diaphragm are environmentally friendly. At the same time, the polymer network structure has a certain bonding effect and can replace the glue layer.

[0050] Other features and advantages of the present invention will be described in detail in the following detailed description. DETAILED DESCRIPTION

[0051] The present invention discloses a diaphragm and a method for preparing the same and a battery. Those skilled in the art can refer to the contents of this article and appropriately improve the process parameters to achieve the same. It should be particularly noted that all similar substitutions and modifications are obvious to those skilled in the art and are deemed to be included in the present invention. The methods and applications of the present invention have been described through preferred embodiments, and relevant personnel can obviously modify or appropriately change and combine the methods and applications described herein without departing from the content, spirit and scope of the present invention to implement and apply the technology of the present invention.

[0052] In the description of the present invention, a list of items connected by the term "at least one of" or other similar terms may mean any combination of the listed items. For example, if items A, B are listed, the phrase "at least one of A, B" means only A; only B; or A and B. In another example, if items A, B, C are listed, the phrase "at least one of A, B, C" means only A; or only B; only C; A and B (excluding C); A and C (excluding B); B and C (excluding A); or all of A, B, and C. Item A may include a single element or multiple elements. Item B may include a single element or multiple elements. Item C may include a single element or multiple elements.

[0053] The endpoints and any values ​​of the ranges disclosed in this article are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of each range, the endpoint values ​​of each range or the individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this article.

[0054] If not otherwise specified, all embodiments and optional embodiments of the present application can be combined with each other to form a new technical solution.

[0055] Unless otherwise specified, all technical features and optional technical features of this application can be combined with each other to form a new technical solution.

[0056] If there is no special explanation, the "include" and "comprising" mentioned in this application are open-ended or closed-ended. For example, the "include" and "comprising" may mean that other components not listed may also be included or only the listed components may be included or only the listed components may be included.

[0057] Generally, a battery includes an electrode assembly and an electrolyte. The electrode assembly includes a positive electrode sheet, a negative electrode sheet and a diaphragm (also called a separator). The diaphragm is arranged between the positive electrode sheet and the negative electrode sheet and mainly plays the role of preventing the positive and negative electrodes from short-circuiting. It can also allow active ions to pass freely to form a loop. With the application and promotion of batteries such as secondary batteries, people have higher and higher requirements for battery performance. By selecting a suitable base membrane and coating the surface of the base membrane with coatings of different functions, different effects can be presented in the battery. In the related art, the main substance in the most widely used coating material is polyvinylidene fluoride (PVDF). However, PVDF contains fluorine elements. The presence of a large amount of PVDF in the coating material will cause irreversible damage to the environment. At the same time, PVDF has limited liquid absorption rate and liquid retention capacity, and does not have the ability to adsorb and lock ions.

[0058] In view of this, the present application proposes a diaphragm and a preparation method thereof and a battery, wherein the main component of the diaphragm does not contain fluorine atoms and is pollution-free, and can adsorb metal ions, thereby improving the ability to store electrolyte and the desolvation ability. The present application and optional embodiments are described in more detail below.

[0059] [Diaphragm]

[0060] In some embodiments, the present invention provides a diaphragm, the diaphragm comprising a base film and a coating disposed on at least one surface of the base film along a thickness direction;

[0061] The coating comprises a metal organic framework material and a gel electrolyte;

[0062] The gel electrolyte comprises: a random copolymer including a first polymer and a second polymer;

[0063] Wherein, the polymerization monomers of the first polymer include acrylate monomers and acrylamide monomers;

[0064] The polymerization monomers of the second polymer include glycidyl ether monomers.

[0065] The diaphragm of the present application mainly includes a base film and a coating disposed on the base film, wherein the coating mainly includes a metal organic framework material and a gel electrolyte, wherein the gel electrolyte comprises a random copolymer obtained by polymerization of acrylate monomers, acrylamide monomers and glycidyl ether monomers. After the coating in the diaphragm is soaked in the electrolyte, the gel electrolyte in the coating absorbs the electrolyte and becomes gel-like, thereby improving the interface contact between the diaphragm and the electrolyte, thereby enhancing the ion transmission capacity of the diaphragm in the battery, thereby reducing the internal resistance and effectively improving the cycle performance of the battery; at the same time, the absorption of electrolyte by the gel electrolyte can also reduce battery leakage and improve the safety performance of the battery cell; the metal organic framework material has a high porosity and excellent chemical stability, and the gel electrolyte and the metal organic framework material are used in combination to capture Ni2+ , Cu 2+ , Fe 3+ , Mn 2+ 、Co 2+ Metal ions such as ions, and the gel electrolyte has a strong ability to absorb electrolytes, and after absorbing electrolytes, it expands in volume, thus improving the capacity and desolvation capacity of the electrolyte, achieving the effect of 1+1>2. In addition, the gel electrolyte is obtained by polymerization of acrylate monomers, acrylamide monomers and glycidyl ether monomers, and there is no fluorine element in the raw materials, so the main components of the final diaphragm are pollution-free and environmentally friendly. At the same time, the gel electrolyte has a polymer network structure, a high swelling liquid absorption rate, and a certain bonding effect, which can replace the glue layer.

[0066] Therefore, compared with PVDF commonly used in current diaphragm coatings, the diaphragm coating provided by the present invention includes a metal organic framework material and a gel electrolyte, wherein the gel electrolyte comprises a random copolymer obtained by polymerization of an acrylate monomer, an acrylamide monomer and a glycidyl ether monomer, and the coating does not contain fluorine in its main components, is environmentally friendly, and has excellent liquid absorption and liquid retention rates, and can capture Ni 2+ , Cu 2+ , Fe 3+ , Mn 2+ 、Co 2+ Metal ions such as ions can enhance the capacity and desolvation ability of the electrolyte.

[0067] In this application, the term "metal organic framework material" mainly refers to coordination polymers (formed by new cations, anions and neutral ligands) self-assembled from multidentate organic ligands containing oxygen, nitrogen, etc. (mostly aromatic polyacids and polybases) and transition metal ions.

[0068] In the present application, the structural formula of the term "acrylate monomer" is CH2=CH-COOR, wherein R represents different organic groups, which may be alkyl, aryl, hydroxyalkyl, etc.

[0069] In the present application, the structural formula of the term "acrylamide monomer" is CH2=CH-CONR1R2, wherein R1 and R2 can be hydrogen atoms, alkyl groups, aryl groups, etc.

[0070] In the present application, the structural formula of the term "glycidyl ether monomer" is RO-CH2-CH(CH2O), wherein R is an organic group.

[0071] In this application, the term "random copolymer" generally refers to a copolymer in which different monomer units are arranged irregularly in the polymer chain. During the polymerization process, the monomer units are connected in a random manner without a specific order or pattern. For example, a random copolymer formed by the polymerization of monomer A and monomer B has a random distribution of A and B monomer units on its molecular chain without periodicity or sequence. For example, -ABBAABAB-.

[0072] In some specific embodiments, the mass ratio of the metal organic framework material and the gel electrolyte is (15-40): (3-10). As an example, the mass ratio of the metal organic framework material and the gel electrolyte in the coating can be any point value among 15:3, 20:4, 25:5, 30:7, 35:9, 40:10, 40:7, 40:5, 40:3, or any range value between two of them. By adjusting the mass ratio of the metal organic framework material and the gel electrolyte within the above range, it helps to improve the ion transport capacity of the diaphragm in the battery cell, reduce the internal resistance, and effectively improve the cycle performance of the battery cell; at the same time, the capacity and desolvation capacity of the electrolyte are improved.

[0073] In some specific embodiments, the coating further includes a binder and a dispersant. That is, the coating includes a metal organic framework material, a gel electrolyte binder and a dispersant. By adding a binder and a dispersant to the coating, the physical and chemical properties of the diaphragm can be further improved, wherein the binder can further improve the bonding strength (also known as peeling force) of the coating, and the dispersant can prevent the coating from settling during the coating process, thereby improving the surface density consistency of the diaphragm.

[0074] In some specific embodiments, the mass ratio of the metal organic framework material, the gel electrolyte, the binder and the dispersant is (15-40): (3-10): (1-5): (0.5-3). As an example, the mass ratio of the metal organic framework material, the binder and the dispersant in the coating is any point value among 15:3:1:0.5, 20:5:2:1, 25:6:3:1.5, 30:7:4:2.5, 35:8:5:3, 40:9:5:3, 40:9:1:2, 40:10:3:1 or any range value between two of them. By controlling the mass ratio of the binder and the dispersant within the above range, the physical and chemical properties of the diaphragm, such as bonding strength and dispersion performance, can be further improved.

[0075] In some specific embodiments, the binder includes, but is not limited to, at least one of polyvinylidene fluoride, carboxymethyl cellulose or polyacrylic acid; preferably, the polyvinylidene fluoride includes polyvinylidene fluoride 5130 (PVDF5130) and / or polyvinylidene fluoride 900 (PVDF900), such as polyvinylidene fluoride may include polyvinylidene fluoride 5130, or may include polyvinylidene fluoride 900, or may include polyvinylidene fluoride 5130 and polyvinylidene fluoride 900 at the same time.

[0076] In some specific embodiments, the dispersant includes, but is not limited to, at least one of a cationic polymer dispersant, polyethylene, polypropylene or polystyrene; preferably, the cationic polymer dispersant includes KD-1.

[0077] The present invention has no particular limitation on the source of the metal organic framework material, which can be purchased from a commercial source or prepared by itself. Those skilled in the art can select the material as needed, as long as a diaphragm that meets the requirements of the present invention can be prepared.

[0078] In some specific embodiments, the mass ratio of the acrylate monomer to the acrylamide monomer is (1.2-3):1. As an example, the mass ratio of the acrylate monomer to the acrylamide monomer can be any value among 1.2:1, 1.5:1, 2:1, 2.5:1, 3:1, or a range value between any two of them. By adjusting the mass ratio of the acrylate monomer to the acrylamide monomer within the above range, the adhesion of the diaphragm can be improved while ensuring the air permeability of the diaphragm.

[0079] In some specific embodiments, the mass ratio of the acrylic acid ester monomer to the glycidyl ether monomer is (60-90):(10-20). As an example, the mass ratio of the acrylic acid ester monomer to the glycidyl ether monomer can be any one of 60:10, 60:15, 60:20, 65:10, 65:15, 65:20, 70:10, 70:15, 70:20, 80:10, 80:20, 85:10, 85:20, 90:10, 90:20 or a range between any two of them.

[0080] In some specific embodiments, the acrylic acid ester monomer includes, but is not limited to, at least one of methyl methacrylate, methyl acrylate, ethyl acrylate, n-butyl acrylate, and ethyl methacrylate.

[0081] In some specific embodiments, the acrylamide monomer includes, but is not limited to, at least one of N-isopropylacrylamide, acrylamide or N,N-dimethylacrylamide.

[0082] In some specific embodiments, the glycidyl ether monomer includes, but is not limited to, at least one of neopentyl glycol diglycidyl ether, 1,4-butanediol diglycidyl ether, ethylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether or 1,6-hexanediol diglycidyl ether.

[0083] By selecting the above-mentioned acrylate monomers, acrylamide monomers and glycidyl ether monomers, a gel electrolyte with a polymer network structure can be prepared. The swelling liquid absorption rate is high, and the gel electrolyte has a certain bonding effect and can replace the glue layer. At the same time, there is no fluorine element in the raw materials, which is environmentally friendly. Furthermore, the gel electrolyte prepared from the above-mentioned monomers can absorb the electrolyte to become a gel, improve the interface contact between the diaphragm and the electrolyte, and enhance the ion transmission ability of the diaphragm in the battery cell, thereby reducing the internal resistance and effectively improving the cycle performance of the battery cell.

[0084] However, the present application is not limited to these acrylate monomers, acrylamide monomers and glycidyl ether monomers, and the present application may also use other acrylate monomers, acrylamide monomers and glycidyl ether monomers that can be used as gel electrolytes. The above substances may be used alone or in combination of two or more.

[0085] In some specific embodiments, the base film has a thickness of 5 to 10 μm. As an example, the base film may have a thickness of 5 μm, 6 μm, 7 μm, 8 μm, 9 μm or 10 μm, or a range of values ​​between any two of the above.

[0086] In some specific embodiments, the thickness of the coating is 3 to 6 μm. As an example, the thickness of the coating can be any point value of 3 μm, 3.5 μm, 4 μm, 4.5 μm, 5 μm, 5.5 μm or 6 μm, or a range of values ​​between any two of them. By adjusting the thickness of the coating within the above range, the internal resistance of the battery can be reduced and the battery cycle performance can be improved; if the thickness of the coating is too thick, it may increase the internal resistance of the battery and reduce the first efficiency and cycle performance of the battery; if the thickness of the coating is too thin, the effect of reducing the internal resistance of the battery is not obvious.

[0087] [Method for preparing diaphragm]

[0088] In some embodiments, the present invention provides a method for preparing a diaphragm, comprising the following steps:

[0089] The acrylate monomer and the acrylamide monomer are subjected to a first polymerization reaction to obtain an intermediate; the intermediate and the glycidyl ether monomer are subjected to a second polymerization reaction to obtain a gel electrolyte;

[0090] Mixing the gel electrolyte, the metal organic framework material and the first solvent to obtain a slurry;

[0091] The slurry is applied on at least one surface of the base film along the thickness direction to obtain a separator.

[0092] It should be understood that all the features and advantages described above for the "diaphragm" are also applicable to the "method for preparing the diaphragm", and will not be described in detail here.

[0093] In the present application, acrylate monomers and acrylamide monomers are subjected to free radical polymerization to obtain an intermediate, and the intermediate is subjected to polymerization reaction with a glycidyl ether monomer to obtain a gel electrolyte, that is, a water-soluble gel electrolyte is generated by in-situ polymerization. This preparation method can reduce side reaction products, reduce the impact of side reaction products on the battery, and improve the reaction efficiency. That is, the preparation of the gel electrolyte in the present application is completed outside the battery cell and then injected into the battery cell for use. Compared with the existing method of preparing the gel electrolyte by polymerization in the battery cell, the reaction efficiency is higher. Because the reaction outside the battery cell to prepare the gel electrolyte makes it easier to remove the generated by-products, reducing the impact of the by-products on the battery cell. Compared with the method of preparing the gel electrolyte by polymerization in the battery cell, the reaction efficiency of the gel electrolyte prepared by this method can be increased from 80% to 97%. In addition, the above-mentioned acrylate monomers, acrylamide monomers and glycidyl ethers can be used to prepare a gel electrolyte with a polymer network structure, which has a certain bonding effect and can replace the glue layer. At the same time, there is no fluorine element in the raw materials, which is environmentally friendly; the gel electrolyte prepared from the above-mentioned monomers can absorb the electrolyte to become a gel, improve the interface contact between the diaphragm and the electrolyte, and enhance the ion transmission ability of the diaphragm in the battery cell, thereby reducing the internal resistance and effectively improving the cycle performance of the battery cell; at the same time, the gel electrolyte absorbs the electrolyte to reduce battery leakage and improve the safety performance of the battery cell.

[0094] Furthermore, the gel electrolyte and the metal organic framework material are used in combination. The metal organic framework material has high porosity and excellent chemical stability. The gel electrolyte and the metal organic framework material are used in combination to capture Ni 2 + , Cu 2+ , Fe 3+ , Mn 2+ 、Co 2+ Metal ions such as ions can enhance the capacity and desolvation ability of the electrolyte, achieving the effect of 1+1>2.

[0095] In some specific embodiments, the first polymerization process comprises:

[0096] The acrylate monomer, the acrylamide monomer, the first initiator and the second solvent are mixed and subjected to a first polymerization reaction to obtain an intermediate.

[0097] In some specific embodiments, the second polymerization process comprises:

[0098] The intermediate solution, the glycidyl ether monomer solution and the second initiator are mixed to carry out a second polymerization reaction to obtain a gel electrolyte.

[0099] In some specific embodiments, the mass ratio of the acrylate monomer to the acrylamide monomer is (1.2-3): 1. As an example, the mass ratio of the acrylate monomer to the acrylamide monomer can be any value among 1.2: 1, 1.5: 1, 2: 1, 2.5: 1, 3: 1, or a range between any two values.

[0100] In some specific embodiments, the mass ratio of the acrylate monomer to the first initiator is (100-120):(0.75-1). As an example, the mass ratio of the acrylate monomer to the initiator can be any value among 100:0.75, 100:1, 102:1, 105:1, 106:1, 108:1, 110:1, 112:1, 115:1, 118:1 or 120:1, or a range between any two of them.

[0101] In some specific embodiments, the mass ratio of the intermediate solution to the glycidyl ether monomer solution is (4-12): 1. As an example, the mass ratio of the intermediate solution to the glycidyl ether monomer solution can be any value among 4:1, 5:1, 6:1, 7:1, 8:1, 9:1, 10:1, 11:1 or 12:1, or a range between any two values.

[0102] In some specific embodiments, the concentration of the intermediate in the intermediate solution is 8-12 wt %. As an example, the concentration of the intermediate in the intermediate solution can be any value among 8 wt %, 9 wt %, 10 wt %, 11 wt % or 12 wt % or any range between the two.

[0103] In some specific embodiments, the mass ratio of the intermediate solution to the second initiator is 100:(0.2-0.4). As an example, the mass ratio of the intermediate solution to the second initiator can be any value of 100:0.2, 100:0.25, 100:0.28, 100:0.3, 100:0.32, 100:0.35 or 100:0.4 or a range between any two values. Preferably, the mass ratio of the intermediate solution to the second initiator is 100:0.25.

[0104] In some specific embodiments, the concentration of the glycidyl ether monomer solution is 0.5-1.2wt%. As an example, the concentration of the glycidyl ether monomer solution can be any value among 0.5wt%, 0.6wt%, 0.7wt%, 0.8wt%, 0.9wt%, 1wt%, 1.2wt% or 1.2wt%, or any range between two values.

[0105] Therefore, controlling the above process parameters within the given range is conducive to preparing high-quality gel electrolytes, and can further improve the performance of the separator of the present application. Those skilled in the art can selectively adjust one or more of the above process parameters according to actual production conditions.

[0106] In some specific embodiments, the first initiator and the second initiator independently include, but are not limited to, azobisisobutyronitrile solution, ammonium persulfate solution or potassium persulfate solution. Preferably, the concentration of the azobisisobutyronitrile solution, ammonium persulfate solution or potassium persulfate solution is independently 70-80 g / L.

[0107] In some embodiments, the solvent in the intermediate solution includes, but is not limited to, water.

[0108] In some specific embodiments, the solvent in the glycidyl ether monomer solution includes, but is not limited to, water.

[0109] In some specific embodiments, the temperature of the first polymerization is 20-45°C, and the time of the first polymerization is 3-7 hours. As an example, the temperature of the first polymerization can be any point value of 20°C, 24°C, 25°C, 28°C, 30°C, 35°C, 38°C, 40°C or 45°C, or a range value between any two of them, and the time of the first polymerization is any point value of 3h, 4h, 5h, 6h or 7h, or a range value between any two of them.

[0110] In some specific embodiments, the temperature of the second polymerization reaction is 20-45°C, and the time of the second polymerization is 2-4 hours. As an example, the temperature of the second polymerization can be any point value of 20°C, 24°C, 25°C, 28°C, 30°C, 35°C, 38°C, 40°C or 45°C, or a range value between any two of them, and the time of the second polymerization is any point value of 2h, 2.5h, 3h, 3.5h or 4h, or a range value between any two of them.

[0111] In some specific embodiments, after the second polymerization reaction is completed, a post-treatment is further included.

[0112] The post-treatment includes: after the second polymerization reaction is completed, the obtained product is heated and then sieved to obtain a gel electrolyte. By heating and sieving the product after the second polymerization reaction, some slightly larger particles are sieved out to improve its stability so as to facilitate the subsequent coating of the slurry on the base film.

[0113] In some specific embodiments, the temperature of the heating treatment is 18-35°C, and the time of the heating treatment is 2-4 hours. As an example, the temperature of the heating treatment can be any point value of 18°C, 20°C, 24°C, 25°C, 26°C, 30°C, 32°C or 35°C, or a range value between any two of them, and the time of the heating treatment is any point value of 2h, 2.5h, 3h, 3.5h or 4h, or a range value between any two of them.

[0114] In some specific embodiments, the sieve has a mesh size of 200 to 300. As an example, the sieve has a mesh size of 200, 220, 240, 250, 260, 280 or 300, or a range of any two of them.

[0115] As an example, the preparation of the gel electrolyte specifically includes:

[0116] 1.2-3 g of an acrylate monomer such as methyl methacrylate, methyl acrylate, ethyl acrylate, n-butyl acrylate or ethyl methacrylate, 1 g of an acrylamide monomer such as N-isopropylacrylamide, acrylamide or N,N-dimethylacrylamide, an initiator such as an azobisisobutyronitrile solution, an ammonium persulfate solution or a potassium persulfate solution and water are mixed to obtain a mixed solution, wherein the mass ratio of the acrylate monomer to the first initiator is (100-120):1, and the concentration of the azobisisobutyronitrile solution, the ammonium persulfate solution or the potassium persulfate solution is independently 70-80 g / L, and then a polymerization reaction is carried out at 20-45° C. for 3-7 hours to obtain an intermediate;

[0117] 8-12 wt % of the intermediate aqueous solution, 0.5-1.2 wt % of the glycidyl ether monomer aqueous solution such as neopentyl glycol diglycidyl ether aqueous solution, 1,4-butanediol diglycidyl ether aqueous solution, ethylene glycol diglycidyl ether aqueous solution, polypropylene glycol diglycidyl ether aqueous solution or 1,6-hexanediol diglycidyl ether aqueous solution and the second initiator such as azobisisobutyronitrile solution, ammonium persulfate solution or potassium persulfate solution are mixed, wherein the intermediate aqueous solution and the glycidyl ether monomer aqueous solution are mixed. The mass ratio of the liquid is (4-12):1, the mass ratio of the intermediate aqueous solution and the second initiator is 100:(0.2-0.4), the concentration of the azobisisobutyronitrile solution, the ammonium persulfate solution or the potassium persulfate solution is independently 70-80 g / L, and then the polymerization reaction is carried out at 20-45° C. for 2-4 hours. After the polymerization reaction is completed, the obtained product is heated at 18-35° C. for 2-4 hours, and then sieved with a sieve opening of 200-300 meshes to obtain a gel electrolyte.

[0118] In some embodiments, the first solvent includes, but is not limited to, water.

[0119] As an example, the preparation of the slurry specifically includes:

[0120] Grinding the metal organic framework material to obtain a metal organic framework material with a particle size of 0.55 to 0.65 μm;

[0121] The ground metal organic framework material, gel electrolyte and a first solvent such as water are mixed, and then stirred at a rotation speed of 300 to 1500 rpm for 1 to 3 hours. After the stirring is completed, defoaming treatment is performed, and then sieved through a 200 to 300 mesh screen to obtain a slurry, wherein the content of the ground metal organic framework material is 15% to 40%, and the content of the gel electrolyte is 3% to 10%.

[0122] In some specific embodiments, the slurry further includes a binder and a dispersant. That is, the gel electrolyte, the metal organic framework material, the binder, the dispersant and the first solvent are mixed to obtain the slurry.

[0123] In some specific embodiments, the binder includes, but is not limited to, at least one of polyvinylidene fluoride, carboxymethyl cellulose or polyacrylic acid; preferably, the polyvinylidene fluoride includes polyvinylidene fluoride 5130 (PVDF5130) and / or polyvinylidene fluoride 900 (PVDF900).

[0124] In some specific embodiments, the dispersant includes at least one of a cationic polymer dispersant, polyethylene, polypropylene or polystyrene; preferably, the cationic polymer dispersant includes KD-1.

[0125] In some specific embodiments, the coating method includes roller coating.

[0126] In some specific embodiments, after the coating is completed, post-treatment is also included.

[0127] The post-treatment includes: coating the slurry and then drying it to obtain a diaphragm.

[0128] As an example, the preparation of the diaphragm specifically includes:

[0129] The slurry is coated, for example, by roll coating, on a base film such as a polypropylene base film and then dried to obtain a separator.

[0130] In some embodiments, the present invention provides a battery, comprising the above-mentioned separator or the separator made by the above-mentioned method.

[0131] The battery mentioned in the embodiments of the present application may be a single physical module including one or more battery cells to provide higher voltage and capacity. For example, the battery mentioned in the present application may be a battery cell, or the battery may include a battery module (or battery module) or a battery pack, etc.

[0132] In some embodiments, the battery includes an electrode assembly and an electrolyte. The electrode assembly includes a positive electrode sheet, a negative electrode sheet, and a separator between the positive electrode sheet and the negative electrode sheet. The electrode assembly can be a wound structure or a laminated structure, which is not limited in the embodiments of the present application.

[0133] In some embodiments, the battery may be a battery module; when there are multiple battery cells, the multiple battery cells are arranged and fixed to form a battery module.

[0134] In some embodiments, the battery may be a battery pack, which may include a case and battery cells, wherein the battery cells or battery modules are accommodated in the case.

[0135] It should be understood that multiple battery cells can be assembled into a battery module or a battery pack. The number of battery cells contained in a battery module or a battery pack can be multiple, and the specific number can be adjusted according to the application and capacity of the battery module or battery pack.

[0136] In some embodiments, the battery may be an energy storage device, which includes an energy storage container, an energy storage cabinet, and the like.

[0137] In the embodiments of the present application, the preparation method of the battery cell or the battery is well known. In some embodiments, the positive electrode sheet, the separator, the negative electrode sheet and the electrolyte can be assembled to form a battery cell. As an example, the positive electrode sheet, the separator and the negative electrode sheet can be formed into an electrode assembly through a winding process and / or a lamination process, and the electrode assembly is placed in an outer package, and the electrolyte is injected after drying. After vacuum packaging, standing, forming, shaping and other processes, a battery cell is obtained. Optionally, multiple battery cells can be further connected in series or in parallel or in a mixed connection to form a battery module. Optionally, multiple battery modules can also be connected in series or in parallel or in a mixed connection to form a battery pack. Optionally, in some embodiments, multiple battery cells can also directly form a battery pack.

[0138] The present invention is further described in detail by way of examples. The raw materials used in the examples can be obtained through commercial sources.

[0139] In the following examples, the metal organic framework materials (MOFs) used were purchased from Carbon Language New Materials, model KAR-F02.

[0140] Example 1

[0141] The preparation of gel electrolyte comprises the following steps:

[0142] Methyl methacrylate, N-isopropylacrylamide, ammonium persulfate solution and water are mixed, and polymerization reaction is carried out at a speed of 400 rpm and a temperature of 20° C. for 3 hours to obtain an intermediate; wherein the mass ratio of methyl methacrylate to N-isopropylacrylamide is 1.5:1, the mass ratio of methyl methacrylate to ammonium persulfate solution is 100:1, and the concentration of the ammonium persulfate solution is 70 g / L;

[0143] 60 g of an intermediate aqueous solution with a concentration of 12 wt % and 5 g of a neopentyl glycol diglycidyl ether aqueous solution with a concentration of 0.5 wt % and an ammonium persulfate solution were mixed, and a polymerization reaction was carried out at a rotation speed of 800 rpm and a temperature of 20° C. for 4 hours. After the polymerization reaction, the resulting product was heated at a rotation speed of 1000 rpm and a temperature of 18° C. for 4 hours, and then passed through a 200-mesh sieve to obtain a gel electrolyte with an average diameter of 0.33 μm and a solid content of 35 wt %; wherein the mass ratio of the intermediate aqueous solution to the ammonium persulfate solution was 100:0.25, and the concentration of the ammonium persulfate solution was 70 g / L.

[0144] The preparation of the diaphragm comprises the following steps:

[0145] Grinding the metal organic framework material (MOFs) to obtain a metal organic framework material with a particle size of 0.6 μm;

[0146] The ground metal organic framework material, the gel electrolyte prepared in Example 1, the binder carboxymethyl cellulose, the dispersant polystyrene and water are mixed, and then stirred at a speed of 1000 rpm for 2 hours. After the stirring is completed, a defoaming treatment is performed, and then a 300-mesh sieve is passed to obtain a slurry; wherein the content of the ground metal organic framework material is 20wt%, the content of the gel electrolyte is 5wt%, the content of the binder is 3wt%, and the content of the dispersant is 2wt%;

[0147] The slurry was roll-coated on a polyethylene-based film with a thickness of 5 μm, and dried to obtain a diaphragm; wherein the thickness of the coating on the diaphragm was 5 μm.

[0148] Example 2

[0149] The preparation of gel electrolyte comprises the following steps:

[0150] Methyl methacrylate, N-isopropylacrylamide, ammonium persulfate solution and water are mixed, and a polymerization reaction is carried out at a speed of 1000 rpm and a temperature of 45° C. for 7 hours to obtain an intermediate; wherein the mass ratio of methyl methacrylate to N-isopropylacrylamide is 1.2:1, the mass ratio of methyl methacrylate to ammonium persulfate solution is 100:1, and the concentration of the ammonium persulfate solution is 70 g / L;

[0151] 50 g of an intermediate aqueous solution with a concentration of 8 wt %, 8 g of a neopentyl glycol diglycidyl ether aqueous solution with a concentration of 1.2 wt % and an ammonium persulfate solution were mixed, and a polymerization reaction was carried out at a rotation speed of 1200 rpm and a temperature of 30° C. for 2 h. After the polymerization reaction, the resulting product was heated at a rotation speed of 800 rpm and a temperature of 25° C. for 2 h, and then passed through a 200-mesh sieve to obtain a gel electrolyte with an average diameter of 0.37 μm and a solid content of 29 wt %; wherein the mass ratio of the intermediate aqueous solution to the ammonium persulfate solution was 100:0.25, and the concentration of the ammonium persulfate solution was 70 g / L.

[0152] The preparation of the diaphragm comprises the following steps:

[0153] Grinding the metal organic framework material (MOFs) to obtain a metal organic framework material with a particle size of 0.6 μm;

[0154] The ground metal organic framework material, the gel electrolyte prepared in Example 1, the binder carboxymethyl cellulose, the dispersant polystyrene and water are mixed, and then stirred at a speed of 1000 rpm for 2 hours. After the stirring is completed, a defoaming treatment is performed, and then a 300-mesh sieve is passed to obtain a slurry; wherein the content of the ground metal organic framework material is 20wt%, the content of the gel electrolyte is 5wt%, the content of the binder is 3wt%, and the content of the dispersant is 2wt%;

[0155] The slurry was roll-coated on a polyethylene-based film with a thickness of 5 μm, and dried to obtain a diaphragm; wherein the thickness of the coating on the diaphragm was 5 μm.

[0156] Example 3

[0157] The preparation of gel electrolyte comprises the following steps:

[0158] Methyl methacrylate, N-isopropylacrylamide, ammonium persulfate solution and water are mixed, and polymerization reaction is carried out at a speed of 1600 rpm and a temperature of 30° C. for 5 hours to obtain an intermediate; wherein the mass ratio of methyl methacrylate to N-isopropylacrylamide is 1.3:1, the mass ratio of methyl methacrylate to ammonium persulfate solution is 100:1, and the concentration of the ammonium persulfate solution is 70 g / L;

[0159] 45 g of an intermediate aqueous solution with a concentration of 10 wt %, 10 g of a neopentyl glycol diglycidyl ether aqueous solution with a concentration of 1 wt % and an ammonium persulfate solution were mixed, and a polymerization reaction was carried out at a rotation speed of 1400 rpm and a temperature of 45° C. for 3 h. After the polymerization reaction, the resulting product was heated at a rotation speed of 900 rpm and a temperature of 35° C. for 3 h, and then passed through a 200-mesh sieve to obtain a gel electrolyte with an average diameter of 0.4 μm and a solid content of 27 wt %; wherein the mass ratio of the intermediate aqueous solution to the ammonium persulfate solution was 100:0.25, and the concentration of the ammonium persulfate solution was 70 g / L.

[0160] The preparation of the diaphragm comprises the following steps:

[0161] Grinding the metal organic framework material (MOFs) to obtain a metal organic framework material with a particle size of 0.6 μm;

[0162] The ground metal organic framework material, the gel electrolyte prepared in Example 1, the binder carboxymethyl cellulose, the dispersant polystyrene and water are mixed, and then stirred at a speed of 1000 rpm for 2 hours. After the stirring is completed, a defoaming treatment is performed, and then a 300-mesh sieve is passed to obtain a slurry; wherein the content of the ground metal organic framework material is 20wt%, the content of the gel electrolyte is 5wt%, the content of the binder is 3wt%, and the content of the dispersant is 2wt%;

[0163] The slurry was roll-coated on a polyethylene-based film with a thickness of 5 μm, and dried to obtain a diaphragm; wherein the thickness of the coating on the diaphragm was 5 μm.

[0164] Example 4

[0165] The preparation of gel electrolyte comprises the following steps:

[0166] Methyl methacrylate, N-isopropylacrylamide, azobisisobutyronitrile solution and water are mixed, and a polymerization reaction is carried out at a speed of 400 rpm and a temperature of 20° C. for 3 hours to obtain an intermediate; wherein the mass ratio of methyl methacrylate to N-isopropylacrylamide is 3:1, the mass ratio of methyl methacrylate to azobisisobutyronitrile solution is 100:1, and the concentration of the azobisisobutyronitrile solution is 70 g / L;

[0167] 60 g of an intermediate aqueous solution with a concentration of 12 wt %, 5 g of a neopentyl glycol diglycidyl ether aqueous solution with a concentration of 0.5 wt % and an azobisisobutyronitrile solution were mixed, and a polymerization reaction was carried out at a rotation speed of 800 rpm and a temperature of 20° C. for 4 h. After the polymerization reaction, the resulting product was heated at a rotation speed of 1000 rpm and a temperature of 18° C. for 4 h, and then passed through a 200-mesh sieve to obtain a gel electrolyte with an average diameter of 0.4 μm and a solid content of 25 wt %; wherein the mass ratio of the intermediate aqueous solution to the azobisisobutyronitrile solution was 100:0.25, and the concentration of the azobisisobutyronitrile solution was 70 g / L.

[0168] The preparation of the diaphragm comprises the following steps:

[0169] Grinding the metal organic framework material (MOFs) to obtain a metal organic framework material with a particle size of 0.6 μm;

[0170] The ground metal organic framework material, the gel electrolyte prepared in Example 1, the binder carboxymethyl cellulose, the dispersant polystyrene and water are mixed, and then stirred at a speed of 1000 rpm for 2 hours. After the stirring is completed, a defoaming treatment is performed, and then a 300-mesh sieve is passed to obtain a slurry; wherein the content of the ground metal organic framework material is 20wt%, the content of the gel electrolyte is 5wt%, the content of the binder is 3wt%, and the content of the dispersant is 2wt%;

[0171] The slurry was roll-coated on a polyethylene-based film with a thickness of 5 μm, and dried to obtain a diaphragm; wherein the thickness of the coating on the diaphragm was 5 μm.

[0172] Example 5

[0173] The preparation of gel electrolyte comprises the following steps:

[0174] Methyl methacrylate, N-isopropylacrylamide, ammonium persulfate solution and water are mixed, and polymerization reaction is carried out at a speed of 400 rpm and a temperature of 20° C. for 3 hours to obtain an intermediate; wherein the mass ratio of methyl methacrylate to N-isopropylacrylamide is 1.5:1, the mass ratio of methyl methacrylate to ammonium persulfate solution is 100:0.75, and the concentration of the ammonium persulfate solution is 70 g / L;

[0175] 60 g of an intermediate aqueous solution with a concentration of 12 wt % and 5 g of a neopentyl glycol diglycidyl ether aqueous solution with a concentration of 0.5 wt % and an ammonium persulfate solution were mixed, and a polymerization reaction was carried out at a rotation speed of 400 rpm and a temperature of 15° C. for 1 hour. After the polymerization reaction, the resulting product was heated at a rotation speed of 1000 rpm and a temperature of 18° C. for 4 hours, and then passed through a 200-mesh sieve to obtain a gel electrolyte with an average diameter of 0.8 μm and a solid content of 20 wt %; wherein the mass ratio of the intermediate aqueous solution to the ammonium persulfate solution is 100:0.25, and the concentration of the ammonium persulfate solution is 70 g / L.

[0176] The preparation of the diaphragm comprises the following steps:

[0177] Grinding the metal organic framework material (MOFs) to obtain a metal organic framework material with a particle size of 0.6 μm;

[0178] The ground metal organic framework material, the gel electrolyte prepared in Example 1, the binder carboxymethyl cellulose, the dispersant polystyrene and water are mixed, and then stirred at a speed of 1000 rpm for 2 hours. After the stirring is completed, a defoaming treatment is performed, and then a 300-mesh sieve is passed to obtain a slurry; wherein the content of the ground metal organic framework material is 20wt%, the content of the gel electrolyte is 5wt%, the content of the binder is 3wt%, and the content of the dispersant is 2wt%;

[0179] The slurry was roll-coated on a polyethylene-based film with a thickness of 5 μm, and dried to obtain a diaphragm; wherein the thickness of the coating on the diaphragm was 5 μm.

[0180] Comparative Example 1

[0181] The preparation of gel electrolyte comprises the following steps:

[0182] Methyl methacrylate, N-isopropylacrylamide, ammonium persulfate solution and water are mixed, and polymerization reaction is carried out at a speed of 300 rpm and a temperature of 15° C. for 2 hours to obtain an intermediate; wherein the mass ratio of methyl methacrylate to N-isopropylacrylamide is 1.5:1, the mass ratio of methyl methacrylate to ammonium persulfate solution is 100:1, and the concentration of the ammonium persulfate solution is 70 g / L;

[0183] 60 g of an intermediate aqueous solution with a concentration of 12 wt % and 5 g of a neopentyl glycol diglycidyl ether aqueous solution with a concentration of 0.5 wt % and an ammonium persulfate solution were mixed, and a polymerization reaction was carried out at a rotation speed of 800 rpm and a temperature of 20° C. for 4 hours. After the polymerization reaction, the resulting product was heated at a rotation speed of 1000 rpm and a temperature of 18° C. for 4 hours, and then passed through a 200-mesh sieve to obtain a gel electrolyte with an average diameter of 4 μm and a solid content of 9 wt %; wherein the mass ratio of the intermediate aqueous solution to the ammonium persulfate solution was 100:0.25, and the concentration of the ammonium persulfate solution was 70 g / L.

[0184] The preparation of the diaphragm comprises the following steps:

[0185] Grinding the metal organic framework material (MOFs) to obtain a metal organic framework material with a particle size of 0.6 μm;

[0186] The ground metal organic framework material, the gel electrolyte prepared in Example 1, the binder carboxymethyl cellulose, the dispersant polystyrene and water are mixed, and then stirred at a speed of 1000 rpm for 2 hours. After the stirring is completed, a defoaming treatment is performed, and then a 300-mesh sieve is passed to obtain a slurry; wherein the content of the ground metal organic framework material is 20wt%, the content of the gel electrolyte is 5wt%, the content of the binder is 3wt%, and the content of the dispersant is 2wt%;

[0187] The slurry was roll-coated on a polyethylene-based film with a thickness of 5 μm, and dried to obtain a diaphragm; wherein the thickness of the coating on the diaphragm was 5 μm.

[0188] Comparative Example 2

[0189] The preparation of gel electrolyte comprises the following steps:

[0190] Methyl methacrylate, N-isopropylacrylamide, ammonium persulfate solution and water are mixed, and polymerization reaction is carried out at a speed of 400 rpm and a temperature of 20° C. for 3 hours to obtain an intermediate; wherein the mass ratio of methyl methacrylate to N-isopropylacrylamide is 1.5:1, the mass ratio of methyl methacrylate to ammonium persulfate solution is 100:1, and the concentration of the ammonium persulfate solution is 70 g / L;

[0191] 60 g of an intermediate aqueous solution with a concentration of 12 wt % and 20 g of a neopentyl glycol diglycidyl ether aqueous solution with a concentration of 0.5 wt % and an ammonium persulfate solution were mixed, and a polymerization reaction was carried out at a rotation speed of 800 rpm and a temperature of 20° C. for 4 hours. After the polymerization reaction, the resulting product was heated at a rotation speed of 1000 rpm and a temperature of 18° C. for 4 hours, and then passed through a 200-mesh sieve to obtain a gel electrolyte with an average diameter of 5 μm and a solid content of 10 wt %; wherein the mass ratio of the intermediate aqueous solution to the ammonium persulfate solution was 100:0.25, and the concentration of the ammonium persulfate solution was 70 g / L.

[0192] The preparation of the diaphragm comprises the following steps:

[0193] Grinding the metal organic framework material (MOFs) to obtain a metal organic framework material with a particle size of 0.6 μm;

[0194] The ground metal organic framework material, the gel electrolyte prepared in Example 1, the binder carboxymethyl cellulose, the dispersant polystyrene and water are mixed, and then stirred at a speed of 1000 rpm for 2 hours. After the stirring is completed, a defoaming treatment is performed, and then a 300-mesh sieve is passed to obtain a slurry; wherein the content of the ground metal organic framework material is 20wt%, the content of the gel electrolyte is 5wt%, the content of the binder is 3wt%, and the content of the dispersant is 2wt%;

[0195] The slurry was roll-coated on a polyethylene-based film with a thickness of 5 μm, and dried to obtain a diaphragm; wherein the thickness of the coating on the diaphragm was 5 μm.

[0196] Test Example 1

[0197] The physical and chemical properties of the separators obtained in the examples and comparative examples were tested, including surface density, needle puncture strength, shrinkage, tensile strength, elongation, air permeability, peel strength and liquid absorption. The test results are shown in Table 1.

[0198] Among them, the test methods involved are as follows:

[0199] (1) Surface density: obtained by sampling a certain area of ​​the diaphragm and calculating the mass / area ratio.

[0200] (2) Shrinkage rate: The diaphragm was placed between two 8 mm thick glass plates and placed in ovens at 130°C and 105°C respectively for 1 h. The diaphragm was taken out and measured to calculate the shrinkage rate.

[0201] (3) Air permeability: At room temperature and 1.21 kPa pressure, 100 mL of air passes through an area of ​​6.45 cm 2 The time taken for the diaphragm.

[0202] (4) Liquid absorption rate: ① Cut 3 pieces of 10 cm × 10 cm diaphragm and place them in a -30°C dew point room for 24 h; ② Weigh and record the mass M1 of the diaphragm sample before immersion in the electrolyte, then completely immerse the diaphragm in the electrolyte and place it in a 28°C (oven) environment for 48 h; ③ Weigh (glove box) the mass M2 of the diaphragm sample after immersion. The weighing method is: unfold the diaphragm in the electrolyte, hold one corner with tweezers and hold it in the air for 60 seconds, then weigh it and record the mass M2; ④ Calculate the liquid absorption rate according to the formula: Liquid absorption rate = (M2-M1) / M1×100%.

[0203] (5) Needle puncture strength, tensile strength, elongation and peel strength: measured by loading different fixtures on a tensile testing machine;

[0204] Among them, the needle diameter is 1.0mm, the puncture rate is 250mm / min, and the puncture strength is calculated based on the puncture force; the tensile strength is measured at a tensile rate of 250mm / min, the clamp distance is 100mm, and the tensile strength and elongation are calculated based on the tensile force; the peel strength refers to peeling at 180°, at a peeling speed of 150mm / min, and the peel strength is calculated based on the peeling force.

[0205] Table 1 Physical and chemical properties of the membranes obtained in the examples and comparative examples

[0206]

[0207]

[0208] As can be seen from Table 1, the method for preparing a water-soluble gel electrolyte provided by the present invention, the prepared water-soluble gel electrolyte can be applied to a battery separator as an aqueous slurry doped with a metal skeleton compound, and has better air permeability, higher peel strength and higher liquid absorption rate than other separators.

[0209] Test Example 2

[0210] The diaphragm obtained in the embodiment and the comparative example is assembled into a battery cell with a lithium iron phosphate positive electrode and a graphite negative electrode through a lamination process, and the amount of electrolyte added when the battery cell is injected (ethylene carbonate (EC) 24wt%, dimethyl carbonate (DMC) 16wt%, ethyl methyl carbonate (EMC) 40wt%, lithium hexafluorophosphate (LiPF6) 15wt%, vinylene carbonate (VC) 2wt%, lithium bis(fluorosulfonyl)imide (LiFSI) 2wt%, vinyl sulfate (DTD) 1wt%) is recorded. At the same time, the cycle performance of the battery cell is tested, including the low-temperature double charge capacity retention rate, the normal temperature cycle capacity retention rate and the high temperature cycle capacity retention rate. The test results are shown in Table 2.

[0211] Cycle performance: The CT3001A blue-electric test system was used to test the battery at low temperature (-5°C), room temperature (20°C) and high temperature (45°C). The charge and discharge range was 2.0 to 3.65V, and the cycle performance was obtained by step cycle test.

[0212] Table 2 Cyclic performance of the batteries composed of the diaphragms obtained in the examples and comparative examples

[0213]

[0214]

[0215] As can be seen from Table 2, the method for preparing a water-soluble gel electrolyte provided by the present invention, the prepared water-soluble gel electrolyte is applied to a battery separator as an aqueous slurry, and has better air permeability, higher peel strength and liquid absorption rate than other separators. After being assembled into a battery cell, the low-temperature double-charge capacity retention rate and the normal temperature and high-temperature cycle capacity retention rate of the battery cell can be improved.

[0216] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A diaphragm, characterized in that: The diaphragm comprises a base film and a coating disposed on at least one surface of the base film in a thickness direction; The coating comprises a metal organic framework material and a gel electrolyte; The gel electrolyte comprises: a random copolymer including a first polymer and a second polymer; Wherein, the polymerization monomers of the first polymer include acrylate monomers and acrylamide monomers; The polymerization monomers of the second polymer include glycidyl ether monomers.

2. The diaphragm according to claim 1, characterized in that The mass ratio of the metal organic framework material to the gel electrolyte is (15-40): (3-10); Preferably, the coating further comprises a binder and a dispersant; Preferably, the mass ratio of the metal organic framework material, gel electrolyte, binder and dispersant is (15-40): (3-10): (1-5): (0.5-3); Preferably, the binder comprises at least one of polyvinylidene fluoride, carboxymethyl cellulose or polyacrylic acid; Preferably, the dispersant comprises at least one of a cationic polymer dispersant, polyethylene, polypropylene or polystyrene.

3. The diaphragm according to claim 1, characterized in that The mass ratio of the acrylic acid ester monomer to the acrylamide monomer is (1.2-3):1; And / or, the mass ratio of the acrylic acid ester monomer to the glycidyl ether monomer is (60-90):(10-20); And / or, the acrylic acid ester monomer includes at least one of methyl methacrylate, methyl acrylate, ethyl acrylate, n-butyl acrylate, and ethyl methacrylate; And / or, the acrylamide monomer includes at least one of N-isopropylacrylamide, acrylamide or N,N-dimethylacrylamide; And / or, the glycidyl ether monomer includes at least one of neopentyl glycol diglycidyl ether, 1,4-butanediol diglycidyl ether, ethylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether or 1,6-hexanediol diglycidyl ether.

4. The diaphragm according to any one of claims 1 to 3, characterized in that: The thickness of the base film is 5 to 10 μm; And / or, the coating has a thickness of 3 to 6 μm.

5. A method for preparing a diaphragm, characterized in that: The following steps are involved: The acrylate monomer and the acrylamide monomer are subjected to a first polymerization reaction to obtain an intermediate; the intermediate and the glycidyl ether monomer are subjected to a second polymerization reaction to obtain a gel electrolyte; Mixing the gel electrolyte, the metal organic framework material and the first solvent to obtain a slurry; The slurry is applied on at least one surface of the base film along the thickness direction to obtain a separator.

6. The method for preparing a diaphragm according to claim 5, characterized in that: The process of the first polymerization reaction comprises: Mixing an acrylate monomer, an acrylamide monomer, a first initiator and a second solvent to perform a first polymerization reaction to obtain an intermediate; And / or, the second polymerization process comprises: The intermediate solution, the glycidyl ether monomer solution and the second initiator are mixed to carry out a second polymerization reaction to obtain a gel electrolyte; Preferably, the mass ratio of the acrylic acid ester monomer to the acrylamide monomer is (1.2-3):1; Preferably, the mass ratio of the intermediate solution to the glycidyl ether monomer solution is (4-12):1; Preferably, the concentration of the intermediate in the intermediate solution is 8 to 12 wt %; Preferably, the concentration of the glycidyl ether monomer solution is 0.5 to 1.2 wt %; Preferably, the solvent in the intermediate solution comprises water; Preferably, the solvent in the glycidyl ether monomer solution includes water.

7. The method for preparing a diaphragm according to claim 5, characterized in that: The temperature of the first polymerization is 20 to 45° C., and the time of the first polymerization is 3 to 7 hours; And / or, the temperature of the second polymerization reaction is 20-45° C., and the time of the second polymerization is 2-4 hours.

8. The method for preparing a diaphragm according to claim 5, characterized in that: After the second polymerization reaction is completed, post-treatment is also included. The post-treatment comprises: after the second polymerization reaction is completed, heating the obtained product and then sieving it to obtain a gel electrolyte; Preferably, the temperature of the heating treatment is 18 to 35° C., and the time of the heating treatment is 2 to 4 hours; Preferably, the sieve opening is 200-300 meshes.

9. The method for preparing a diaphragm according to claim 5, characterized in that: The first solvent includes water; And / or, the slurry further includes a binder and a dispersant; Preferably, the binder comprises at least one of polyvinylidene fluoride, carboxymethyl cellulose or polyacrylic acid; Preferably, the dispersant comprises at least one of a cationic polymer dispersant, polyethylene, polypropylene or polystyrene.

10. A battery, characterized in that: The battery comprises the separator according to any one of claims 1 to 4 or the separator prepared by the method according to any one of claims 5 to 9.

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