Diaphragm and method of manufacturing and use thereof

Abstract

This invention discloses a separator, its preparation method, and its application. The battery separator includes a base membrane and a coating on at least one surface of the base membrane; wherein the coating contains a solid electrolyte, aromatic polyamide, and polyvinylidene fluoride; the mass ratio of the solid electrolyte, aromatic polyamide, and polyvinylidene fluoride is 1:(20-35):(15-25). The battery separator provided by this invention has excellent heat resistance, adhesion, and high-temperature dimensional stability, improving the thermal stability of the separator during use and making it less likely to detach from the electrode during subsequent use; simultaneously, it has excellent ionic conductivity, ensuring that the ionic conductivity of the separator is not affected under high-temperature operation.

Description

Technical Field

[0001] This invention belongs to the field of separator / membrane technology, and more specifically, relates to battery separators, their preparation methods and applications. Background Technology

[0002] Lithium-ion batteries have attracted widespread attention due to their high energy density and long cycle life. The four main materials are the positive electrode material, the negative electrode material, the separator, and the electrolyte. The separator holds the liquid electrolyte, providing a channel for lithium-ion transport. However, the electrolyte is flammable and explosive, the separator is prone to shrinkage at high temperatures, and the interface between the separator and the electrode may not be tightly bonded, leaving gaps and residual gas, which can easily cause safety hazards. Therefore, solid-state batteries have emerged. However, pure solid-state batteries suffer from low ion conductivity, slow ion transport speed, high impedance, and high cost.

[0003] Currently, to reduce the amount of electrolyte used in batteries, existing separators can be modified using solid electrolyte materials with high lithium-ion conductivity. This is mainly achieved by coating the separator with a solid electrolyte to prepare semi-solid-state lithium-ion batteries. Taking lithium lanthanum titanium oxide (LLTO) as an example, LLTO is a diopside-type oxide solid electrolyte with an ion transfer rate as high as 0.5 to 0.9. It exhibits significant chemical and thermal stability even under ambient air conditions, and it does not emit toxic gases during decomposition, making it very environmentally friendly. Furthermore, LLTO has a high ionic conductivity (approximately 10⁻³ S / cm). -1 With its wide electrochemical window and excellent mechanical strength, LLTO effectively enhances its compatibility with high-voltage cathode materials and lithium metal anodes, thus expanding its potential application areas and attracting widespread attention. Although LLTO can improve the ionic conductivity of the separator, it still suffers from poor thermal shrinkage and poor adhesion, which greatly affects the safe operation of the battery.

[0004] Aromatic polyamide fibers are a type of aramid fiber. Commonly used aromatic polyamide fibers include poly(m-phenylene isophthalamide) (aramid 1313 / me-aramid fiber), poly(p-phenylene terephthalamide) (aramid 1414 / aramid II / para-aramid fiber), and poly(phenylene terephthalamide) (aramid sulfone fiber). Aromatic polyamide fibers possess excellent properties such as high strength, high modulus, high temperature resistance, and flame retardancy, making them suitable for various applications. However, improving the poor porosity and easy detachment from the electrode in diaphragms coated with aromatic polyamide fibers remains a crucial issue that needs to be addressed for their large-scale application. Summary of the Invention

[0005] 1. The problem to be solved

[0006] To address the shortcomings of existing coated solid electrolytes in terms of performance, this invention provides a diaphragm.

[0007] Furthermore, the present invention also provides a method for preparing the diaphragm;

[0008] In addition, the present invention also provides a battery containing the aforementioned separator.

[0009] 2. Technical Solution

[0010] The technical solution adopted in this invention is as follows:

[0011] In accordance with the objectives of this invention, a first aspect of this invention provides a diaphragm, the diaphragm comprising:

[0012] Base film;

[0013] A coating located on at least one side surface of the base film;

[0014] in,

[0015] The coating contains a solid electrolyte, aromatic polyamide, and polyvinylidene fluoride, and the mass ratio of the solid electrolyte, aromatic polyamide, and polyvinylidene fluoride is 1:(20-35):(15-25).

[0016] According to any embodiment of the first aspect of the present invention, the solid electrolyte includes a sodium superionic conductor type solid electrolyte, a perovskite type solid electrolyte, and a garnet type solid electrolyte.

[0017] A typical example of a sodium superionic conductor (NASICON) type solid electrolyte is LATP (lithium aluminum titanium phosphate, Li). 1.3 Al 0.3 Ti 1.7 (PO4)3); the representative material of perovskite solid electrolytes is LLTO (lithium lanthanum titanium oxide / lithium lanthanum titanate, Li). 0.33 La 0.56 TiO3); the representative material of garnet-type solid electrolytes is LLZO (lithium lanthanum zirconium oxide / lithium lanthanum zirconate, Li7La3Zr2O). 12 ), LLZTO (lithium lanthanum zirconium tantalum oxide, Li 6.5 La3Zr 1.5 Ta 0.5 O 12 ).

[0018] According to any embodiment of the first aspect of the present invention, the thickness of the base membrane is 3 to 14 μm, and the porosity of the base membrane is 30% to 90%.

[0019] According to any embodiment of the first aspect of the present invention, the base membrane is made of materials including but not limited to polyethylene (PE), polypropylene (PP), polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), polyimide (PI), polyacrylonitrile (PAN), polyethylene terephthalate (PET), cellulose, or any combination of the foregoing materials.

[0020] The representative material of the cellulose can be natural cellulose, such as bacterial cellulose, cellulose acetate, or any combination of the foregoing.

[0021] According to any embodiment of the first aspect of the present invention, the type of the base membrane includes, but is not limited to, polymer membranes and nonwoven membranes;

[0022] Representative polymer films include polyethylene (PE) films, polypropylene (PP) films, polyvinylidene fluoride (PVDF) films, polytetrafluoroethylene (PTFE) films, polyimide (PI) films, polyacrylonitrile (PAN) films, polyethylene terephthalate (PET) films, and polymethyl methacrylate (PMMA) films.

[0023] The nonwoven membrane, also known as a nonwoven fabric membrane, refers to a novel type of membrane manufactured using nonwoven processes such as electrospinning, wet nonwoven fabrication, and meltblowing to orient or randomly arrange uniformly dispersed fibers into a three-dimensional network structure, which is then reinforced by physical methods. Nonwoven membranes can be made from synthetic fibers and natural cellulose, as well as cellulose derivatives. Commonly used nonwoven membrane materials include bacterial cellulose (BC), polyethylene terephthalate (PET), polyimide (PI), polyvinylidene fluoride (PVDF), polyvinylidene fluoride-hexafluoropropylene copolymer (PVDF-HFP), and polytetrafluoroethylene (PTFE). Therefore, representative nonwoven membranes include bacterial cellulose (BC) membranes and cellulose acetate (CA) membranes.

[0024] According to any embodiment of the first aspect of the invention, the coating may be one or both sides of the base film, and the total thickness of the coating is 1 to 14 μm.

[0025] According to any embodiment of the first aspect of the present invention, the diaphragm has:

[0026] A bond strength of not less than 4 N / m; and,

[0027] Peel strength of not less than 20 N / m.

[0028] According to any embodiment of the first aspect of the present invention, the diaphragm has:

[0029] Bond strength of 4–10 N / m; and,

[0030] Peel strength of 20-50 N / m.

[0031] A second aspect of the present invention provides a slurry for preparing a diaphragm, the slurry comprising a solid electrolyte, an aromatic polyamide, polyvinylidene fluoride raw material, and a solvent.

[0032] According to any embodiment of the second aspect of the present invention, the slurry for preparing a diaphragm is wherein the mass ratio of solid electrolyte, aromatic polyamide and polyvinylidene fluoride raw material in the slurry is 1:(20-50):(1-30);

[0033] Meanwhile, the solid content of the solid electrolyte, aromatic polyamide and polyvinylidene fluoride raw material in the slurry is 0.01-8%, 1-15% and 2-10%, respectively.

[0034] According to any embodiment of the second aspect of the present invention, the slurry for preparing the diaphragm may be polyvinylidene fluoride raw material, which may be polyvinylidene fluoride or polyvinylidene fluoride-hexafluoropropylene; optionally, the proportion of hexafluoropropylene in the polyvinylidene fluoride-hexafluoropropylene is 2 to 6 wt%, for example, it may be 2 wt%, 3 wt%, 4 wt%, 4 wt% or 6 wt%.

[0035] According to any embodiment of the second aspect of the present invention, the slurry for preparing a diaphragm includes one or two of polyphenylene isophthalamide fibers (aramid 1313 / meta-aramid fibers), poly(p-phenylene terephthalamide fibers) (aramid 1414 / aramid II / para-aramid fibers), and polyphenylene terephthalamide fibers (aramid sulfone fibers).

[0036] According to any embodiment of the second aspect of the present invention, in order to better ensure the safety of the diaphragm and avoid the possibility of the diaphragm falling off the electrode during use, the aromatic polyamide includes polyphenylene phthalamide fiber (aramid fiber).

[0037] According to any embodiment of the second aspect of the present invention, the aromatic polyamide used in the preparation of the diaphragm is either used as a cellulose solution or added to it.

[0038] According to any embodiment of the second aspect of the present invention, the slurry for preparing a diaphragm contains an aromatic polyamide with a solid content of 5-15%, and the aramid fiber preferably has a solid content of 5-15%.

[0039] Furthermore, the fiber solution can be prepared by the following method: adding aromatic polyamide fibers to an NMP solution containing chloride salts and stirring for 4-6 hours until completely dissolved, the solution being pale yellow and transparent, wherein the ratio of chloride salts to aromatic polyamides is (3-1):1.

[0040] Based on this, in the preparation of aramid fiber solution, the preferred addition ratio of chloride salt and aromatic polyamide is (2-1):1.

[0041] Furthermore, the ratio of chloride salt to aromatic polyamide added to the aramid fiber solution is more preferably 1.5:1.

[0042] Furthermore, the chloride salt may be calcium chloride, potassium chloride, or sodium chloride.

[0043] Furthermore, the viscosity of the fiber solution is 2000–6000 mPa. · s.

[0044] A third aspect of the present invention provides a method for preparing a diaphragm, comprising the steps of:

[0045] S1 Preparation of slurry: The slurry contains a solid electrolyte, aromatic polyamide, polyvinylidene fluoride raw material and solvent;

[0046] The mass ratio of solid electrolyte, aromatic polyamide and polyvinylidene fluoride raw material in the slurry is 1:(20-50):(1-30);

[0047] Meanwhile, the solid content of the solid electrolyte, aromatic polyamide and polyvinylidene fluoride raw material in the slurry is 0.01-8%, 1-15%, and 2-10%, respectively.

[0048] S2 diaphragm preparation: A slurry is coated onto the base membrane. After the slurry coating is completed, the membrane is soaked and dried to obtain the diaphragm.

[0049] According to the method for preparing the diaphragm according to any embodiment of the third aspect of the present invention, the polyvinylidene fluoride raw material can be polyvinylidene fluoride or polyvinylidene fluoride-hexafluoropropylene;

[0050] The number-average molecular weight of the polyvinylidene fluoride-hexafluoropropylene (PVDF-HFP) is 500,000-600,000.

[0051] The proportion of hexafluoropropylene copolymer (HFP) in the polyvinylidene fluoride-hexafluoropropylene (PVDF-HFP) is 2-6 wt%. For example, the proportion of hexafluoropropylene copolymer (HFP) in the polyvinylidene fluoride-hexafluoropropylene (PVDF-HFP) can be 2 wt%, 3 wt%, 4 wt%, 4 wt%, or 6 wt%.

[0052] According to the method for preparing the diaphragm of any embodiment of the third aspect of the present invention, the aromatic polyamide includes one or two of poly(m-phenylene isophthalamide) fiber (aramid 1313 / me-aramid fiber), poly(p-phenylene terephthalamide) fiber (aramid 1414 / aramid II / para-aramid fiber), and poly(phenylene terephthalamide) fiber (aramid sulfone fiber).

[0053] According to any embodiment of the third aspect of the present invention, in order to better ensure the safety of the diaphragm and avoid the possibility of the diaphragm falling off the electrode during use, the aromatic polyamide includes polyphenylene phthalamide fiber (aramid fiber).

[0054] According to the method for preparing the diaphragm of any embodiment of the third aspect of the present invention, the aromatic polyamide is used as a cellulose solution or added thereto.

[0055] According to the method for preparing the diaphragm according to any embodiment of the third aspect of the present invention, the solid content of the aromatic polyamide contained in the fiber solution is 5-15%, and the solid content of the aramid fiber is preferably 5-15%.

[0056] Furthermore, the fiber solution can be prepared by adding aromatic polyamide fibers to an NMP solution containing chloride salts and stirring for 4-6 hours until completely dissolved;

[0057] Based on this, the ratio of chloride salt to aromatic polyamide is (3-1):1;

[0058] Furthermore, in the preparation of the aramid fiber solution, the preferred ratio of chloride salt to aromatic polyamide is (2-1):1.

[0059] Furthermore, the ratio of chloride salt to aromatic polyamide added to the aramid fiber solution is more preferably 1.5:1.

[0060] Furthermore, the chloride salt may be calcium chloride, potassium chloride, or sodium chloride.

[0061] Furthermore, the viscosity of the fiber solution is 2000–6000 mPa. · s.

[0062] According to any embodiment of the third aspect of the present invention, the method for preparing a diaphragm, step S1 includes:

[0063] S1.1 Prepare a suspension containing solid electrolyte and solvent;

[0064] The solid electrolyte is added at a mass concentration of 0.09–5 wt%, preferably at a mass concentration of 0.1–3 wt%.

[0065] S1.2 Prepare a glue solution containing aromatic polyamide, polyvinylidene fluoride raw materials and solvent;

[0066] The aromatic polyamide is added at a mass concentration of 1-10 wt%, preferably at a mass concentration of 2-8 wt%.

[0067] The mass concentration of the polyvinylidene fluoride raw material added is 0.1-10 wt%, preferably 0.1-8 wt%.

[0068] S1.3. The suspension and the adhesive are mixed and dispersed to obtain the slurry;

[0069] Further, one possible operating method for S1.1 is to mix the solid electrolyte with the solvent and disperse the mixture to obtain the suspension. The purpose of "dispersion" as described herein is to achieve a uniform dispersion effect. Therefore, a possible operating method is to perform the dispersion treatment using ultrasound, oscillation, or stirring. Further, the duration of the "ultrasound, oscillation, or stirring treatment" as described herein can be 30–60 minutes.

[0070] Further, one possible operating method for S1.2 is: mixing the polyvinylidene fluoride raw material with a solvent, dispersing it, then adding aromatic polyamide and dispersing it again to obtain the adhesive solution; the purpose of "dispersion" as described herein is to achieve a uniform dispersion effect as much as possible. Based on this, a possible operating method is to perform the dispersion treatment by ultrasound, oscillation, or stirring. Further, the time for "ultrasound, oscillation, or stirring treatment" as described herein can be 10 to 800 minutes.

[0071] Furthermore, the purpose of "dispersion" in S1.3 is to achieve a uniform dispersion effect as much as possible. Based on this, one possible operating method is: ultrasonic, oscillating, or stirring treatment under an ice bath, followed by sieving, and the filtrate passing through the sieve is the "slurry". The "ice bath" can effectively avoid the problem of slurry solidification caused by overheating due to excessively fast dispersion speed. Furthermore, the time for "ultrasonic, oscillating, or stirring treatment under an ice bath" as described herein can be 90-120 minutes, and the mesh size for "sieving" as described herein can be 300-400 mesh.

[0072] According to any embodiment of the third aspect of the present invention, in the method for preparing a diaphragm, in step S1.3, the ratio of the amount (mass) of the suspension to the adhesive solution is 0.1 to 1.

[0073] According to any embodiment of the third aspect of the present invention, in the method for preparing the diaphragm, step S2, the soaking treatment includes: first soaking in N-methylpyrrolidone (NMP) 1 to 2 times, with a single soaking time of 2 to 3 minutes; then soaking in pure water 1 to 6 times, with a single soaking time of 2 to 3 minutes.

[0074] Furthermore, the soaking solution should not be reused after each soaking treatment.

[0075] Furthermore, the N-methylpyrrolidone (NMP) soaking includes soaking in N-methylpyrrolidone (NMP) solutions of different concentrations; based on this, one possible operating method for the N-methylpyrrolidone (NMP) soaking is: first soaking in an N-methylpyrrolidone (NMP) solution with a concentration of 42-48% for 2-3 minutes, and then soaking in an N-methylpyrrolidone (NMP) solution with a concentration of 18-22% for 2-3 minutes.

[0076] According to any embodiment of the third aspect of the present invention, in the method for preparing the diaphragm, in step S2, the drying treatment can be a low-temperature drying treatment or a natural air drying treatment; preferably, low-temperature drying, wherein the drying temperature is 20 to 40°C.

[0077] According to any embodiment of the third aspect of the present invention, the solvent comprises one or a mixture of two or more of N-methylpyrrolidone (NMP), N,N-dimethylacetamide (DMAc), N,N-dimethylformamide, acetone, dimethyl sulfoxide, and triethyl phosphate; the water content of the solvent is less than 1%.

[0078] According to the method for preparing a diaphragm according to any embodiment of the third aspect of the present invention, the viscosity of the adhesive solution obtained in step S1.2 is 100-600 mPa·s;

[0079] The viscosity of the slurry obtained in step S1.3 is 50-500 mPa·s;

[0080] In summary, the membrane preparation method provided by any embodiment of the third aspect of the present invention can be used to prepare the membrane described in any embodiment of the first aspect of the present invention.

[0081] According to the method for preparing the diaphragm of any embodiment of the third aspect of the present invention, it should be noted that:

[0082] For example, by adjusting the temperature during biaxial stretching and transverse stretching, the porosity of the diaphragm can be controlled between 30% and 90%.

[0083] For example, in laboratory coating, the coating thickness can be controlled between 0.5-4μm by adjusting the specifications of the printing bar; in mass production, the coating thickness can also be controlled between 0.5-4μm by adjusting the size of the gravure roller.

[0084] A fourth aspect of the present invention provides a lithium battery comprising a separator;

[0085] The diaphragm comprises the diaphragm described in any embodiment of the first aspect of the present invention; or...

[0086] The diaphragm contains a coating formed after the slurry is applied according to any embodiment of the second aspect of the present invention; or...

[0087] The diaphragm is a diaphragm prepared by the method described in any embodiment of the third aspect of the present invention.

[0088] Any embodiment of any aspect of the present invention can be combined with other embodiments without contradiction. Furthermore, in any embodiment of any aspect of the present invention, any technical feature can be applied to the same technical feature in other embodiments without contradiction.

[0089] Without causing contradictions, any technical feature of any aspect or embodiment of the present invention is equally applicable to any other embodiment or embodiment of any other aspect. Of course, when applicable to each other, appropriate modifications may be made to the corresponding features as necessary. The various aspects and features of the present invention are further described below.

[0090] 3. Beneficial effects

[0091] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0092] The battery separator provided by this invention has excellent heat resistance, adhesion, and high-temperature dimensional stability, which improves the thermal stability of the separator during use and makes it less likely to fall off the electrode during subsequent use.

[0093] At the same time, it has excellent ionic conductivity, which ensures that the ionic conductivity of the membrane is not affected under high temperature operation.

[0094] More specifically, the battery separator provided by the present invention includes a base film and a coating on the surface of the base film. The aramid fiber used in the coating is preferably aramid sulfone fiber. Compared with aramid 1414 fiber and aramid 1313 fiber, aramid sulfone fiber has better compatibility and processability, which can reduce coating difficulty, improve separator safety, and avoid the possibility of the separator falling off the electrode.

[0095] Based on this, the coating of the battery separator provided by the present invention further contains polyvinylidene fluoride or polyvinylidene fluoride-hexafluoropropylene and a solid electrolyte. The solid electrolyte in the coating can improve the heat resistance of the separator, increase its ionic conductivity, further improve the porosity of the aramid coating, and improve the processability of the separator.

[0096] The polyvinylidene fluoride or polyvinylidene fluoride-hexafluoropropylene in the coating has good adhesion and good liquid absorption and retention properties, which improves the contact between the coating and the electrode. This is beneficial for removing air from the internal gaps during the hot pressing process of subsequent battery assembly. The tight adhesion between the separator and the electrode can effectively reduce battery swelling and bulging, while increasing the cell hardness and reducing assembly difficulty. Attached Figure Description

[0097] Figure 1 SEM image of the diaphragm prepared in Experiment Example 1. Detailed Implementation

[0098] The various terms and phrases used in this invention have their general meanings known to those skilled in the art. Nevertheless, this invention still intends to provide a more detailed description and explanation of these terms and phrases. In the event of any inconsistency between the terms and phrases mentioned and their known meanings, the meanings expressed in this invention shall prevail.

[0099] When an item is described using the combined terms “...and / or ...", the description should be understood to include any one of the listed items and all combinations thereof.

[0100] Generally, the use of the term "about" indicates an approximation that can vary depending on the desired characteristics obtained from the disclosed subject matter and will be interpreted in a context-dependent manner based on function. Therefore, those skilled in the art will be able to interpret a degree of difference on a case-by-case basis. In some cases, the number of significant figures used when expressing a particular value can be a representative technique for determining the difference allowed by the term "about." In other cases, a gradient within a range of values ​​can be used to determine the range of differences allowed by the term "about." Furthermore, all ranges in this disclosure are inclusive and composable, and references to values ​​described within a range include every value within that range.

[0101] In this invention, the term "comprising" or "containing" indicates that various ingredients may be used together in the composition of this invention. Therefore, the terms "consistent with..." and "composed of..." are included in the term "comprising" or "containing".

[0102] Unless otherwise defined, "molecular weight" as used in this article refers to average molecular weight.

[0103] Unless otherwise stated, any feature disclosed in this specification may be replaced by other equivalent or similar features. Unless otherwise stated, each feature is merely one example of a series of equivalent or similar features. The descriptions are merely to aid in understanding the invention and should not be construed as limiting the invention. Experimental examples without specific conditions were conducted under standard conditions or conditions recommended by the manufacturer. Reagents or instruments without specified manufacturers are all commercially available, conventional products.

[0104] The invention will be further described below with reference to specific experimental examples.

[0105] Experimental Example 1

[0106] (1) The diaphragm provided in this experimental example is shown in #1 of Table 1. The diaphragm is composed of a polyethylene base film and a coating on both sides of the base film.

[0107] Regarding the coating: the coating contains solid electrolyte LLTO, aromatic polyamide and polyvinylidene fluoride-hexafluoropropylene in a mass ratio of 0.18:6.3:2.7.

[0108] The coating has a thickness of 4 μm.

[0109] Regarding the aforementioned polyethylene-based film: it has a thickness of 7 μm and a porosity of 38%.

[0110] (2) The slurry used for preparing the diaphragm provided in this experimental example is as follows:

[0111] The slurry contains solid electrolyte LLTO, aromatic polyamide, polyvinylidene fluoride-hexafluoropropylene, and solvent;

[0112] The solid contents of the solid electrolyte LLTO, aromatic polyamide, and polyvinylidene fluoride-hexafluoropropylene in the slurry are 0.09%, 3.15%, and 1.35%, respectively.

[0113] The mass ratio of solid electrolyte, aromatic polyamide and polyvinylidene fluoride-hexafluoropropylene in the slurry is 1:35:15;

[0114] The solvent is N-methylpyrrolidone.

[0115] The aromatic polyamide is made from aramid fiber, which was purchased from Shanghai Tanlon Fiber Co., Ltd.

[0116] (3) The raw materials and process for preparing the slurry as described in (2) above are as follows:

[0117] S1.1, Prepare the suspension;

[0118] Specifically, in this experimental example: 0.18g of LLTO was added to 60g of NMP and ultrasonically dispersed for 1h to prepare the suspension.

[0119] S1.2 Prepare an aramid fiber solution (solid content 13%);

[0120] Specifically, in this experimental example, a 13% solids content aramid fiber solution can be prepared by the following method: 46g of calcium chloride is completely dissolved in 160g of NMP by stirring at 80℃ for 30min. Then, 31g of aromatic polyamide fiber is added to the NMP solution containing chloride salt, and the mixture is stirred at 80℃ for 4-6h until completely dissolved, yielding a solution with a solids content of 13% and a viscosity of 5620mPa. · The solution of s aramid fiber (pale yellow and transparent) contains chloride salt and aromatic polyamide fiber in a ratio of 1.5:1.

[0121] S1.3, Prepare the adhesive solution;

[0122] Specifically, in this experimental example: 2.7g of PVDF-HFP powder was added to 88.7g of NMP and mechanically stirred at 500rpm for 40min. Then, 48.5g of aramid fiber solution with a solid content of 13% prepared in S1.2 was added and mechanically stirred at 600rpm for 60min to prepare a composite adhesive containing PVDF-HFP and PSA.

[0123] The polyvinylidene fluoride-hexafluoropropylene copolymer has a number average molecular weight of 500,000-600,000; the proportion of hexafluoropropylene copolymer in the polyvinylidene fluoride-hexafluoropropylene copolymer is 4 wt%.

[0124] S1.4, Obtain the slurry as described in (2) above;

[0125] Specifically, in this experimental example: the suspension prepared in S1.1 above is mixed with the adhesive prepared in S1.3 above, dispersed at high speed in an ice bath for 60 minutes, and then filtered through a 300-mesh filter. The lower layer of filtrate is taken to obtain the coating slurry.

[0126] (4) The process of preparing the diaphragm using the slurry described in (2) above is as follows:

[0127] The slurry described in (2) above (or the slurry prepared in (3) above) is uniformly coated on both sides of the polyethylene film described in (1) above using a No. 40 wire rod;

[0128] After coating, the membrane was first immersed in a coagulation tank with an NMP concentration of 45% for 3 minutes, then in a coagulation tank with an NMP concentration of 20% for 3 minutes, and then in a pure water tank for 3 minutes. The membrane was then immersed twice and finally dried in an oven at 60°C for 20 minutes to obtain a membrane with a thickness of 11 μm and a total coating thickness of 4 μm.

[0129] Experimental Example 2

[0130] (1) The diaphragm provided in this experimental example is shown in #2 of Table 1. The diaphragm is composed of a polyethylene base film and a coating on both sides of the base film.

[0131] Regarding the coating: the coating contains solid electrolyte LLTO, aromatic polyamide and polyvinylidene fluoride-hexafluoropropylene in a mass ratio of 0.18:5.4:3.6.

[0132] The coating has a thickness of 4 μm.

[0133] Regarding the aforementioned polyethylene-based film: it has a thickness of 7 μm and a porosity of 38%.

[0134] (2) The slurry used for preparing the diaphragm provided in this experimental example is as follows:

[0135] The slurry contains solid electrolyte LLTO, aromatic polyamide, polyvinylidene fluoride-hexafluoropropylene, and solvent;

[0136] The solid contents of the solid electrolyte LLTO, aromatic polyamide, and polyvinylidene fluoride-hexafluoropropylene in the slurry are 0.09%, 2.7%, and 1.8%, respectively.

[0137] The mass ratio of solid electrolyte, aromatic polyamide and polyvinylidene fluoride-hexafluoropropylene in the slurry is 1:30:20.

[0138] The solvent is N-methylpyrrolidone.

[0139] The aromatic polyamide is made from aramid fiber, which was purchased from Shanghai Tanlon Fiber Co., Ltd.

[0140] (3) The raw materials and process for preparing the slurry as described in (2) above are as follows:

[0141] S1.1, Prepare the suspension;

[0142] Specifically, in this experimental example: 0.18g of LLTO was added to 60g of NMP and ultrasonically dispersed for 1h to prepare the suspension.

[0143] S1.2 Prepare an aramid fiber solution (solid content 13%);

[0144] Specifically, in this experimental example, a 13% solids content aramid fiber solution can be prepared by the following method: 46g of calcium chloride is completely dissolved in 160g of NMP by stirring at 80℃ for 30min. Then, 31g of aromatic polyamide fiber is added to the NMP solution containing chloride salt, and the mixture is stirred at 80℃ for 4-6h until completely dissolved, yielding a solution with a solids content of 13% and a viscosity of 5620mPa. · The solution of s aramid fiber (pale yellow and transparent) contains chloride salt and aromatic polyamide fiber in a ratio of 1.5:1.

[0145] S1.3, Prepare the adhesive solution;

[0146] Specifically, in this experimental example: 3.6g of PVDF-HFP powder was added to 94.7g of NMP and mechanically stirred at 500rpm for 40min. Then, 41.5g of aramid fiber solution with a solid content of 13% prepared in S1.2 was added and mechanically stirred at 600rpm for 60min to prepare a composite adhesive containing PVDF-HFP and PSA.

[0147] The polyvinylidene fluoride-hexafluoropropylene copolymer has a number average molecular weight of 500,000-600,000; the proportion of hexafluoropropylene copolymer in the polyvinylidene fluoride-hexafluoropropylene copolymer is 4 wt%.

[0148] S1.4, Obtain the slurry as described in (2) above;

[0149] Specifically, in this experimental example: the suspension prepared in S1.1 above is mixed with the adhesive prepared in S1.3 above, dispersed at high speed in an ice bath for 60 minutes, and then filtered through a 300-mesh filter. The lower layer of filtrate is taken to obtain the coating slurry.

[0150] (4) The process of preparing the diaphragm using the slurry described in (2) above is as follows:

[0151] The slurry described in (2) above (or the slurry prepared in (3) above) is uniformly coated on both sides of the polyethylene film described in (1) above using a No. 40 wire rod;

[0152] After coating, the membrane was first immersed in a coagulation tank with an NMP concentration of 45% for 3 minutes, then in a coagulation tank with an NMP concentration of 20% for 3 minutes, and then in a pure water tank for 3 minutes. The membrane was then immersed twice and finally dried in an oven at 60°C for 20 minutes to obtain a membrane with a thickness of 11 μm and a total coating thickness of 4 μm.

[0153] Experimental Example 3

[0154] (1) The diaphragm provided in this experimental example is shown as #3 in Table 1. The diaphragm is composed of a polyethylene base film and a coating on both sides of the base film.

[0155] Regarding the coating described in this experimental example: the coating contains solid electrolyte LLTO, aromatic polyamide, and polyvinylidene fluoride-hexafluoropropylene in a mass ratio of 0.18:4.5:4.5.

[0156] The coating has a thickness of 4 μm.

[0157] Regarding the aforementioned polyethylene-based film: it has a thickness of 7 μm and a porosity of 38%.

[0158] (2) The slurry used for preparing the diaphragm provided in this experimental example is as follows:

[0159] The slurry contains solid electrolyte LLTO, aromatic polyamide, polyvinylidene fluoride-hexafluoropropylene, and solvent;

[0160] The solid contents of the solid electrolyte LLTO, aromatic polyamide, and polyvinylidene fluoride-hexafluoropropylene in the slurry are 0.09%, 2.25%, and 2.25%, respectively.

[0161] The mass ratio of solid electrolyte LLTO, aromatic polyamide, and polyvinylidene fluoride-hexafluoropropylene in the slurry is 1:25:25.

[0162] The solvent is N-methylpyrrolidone.

[0163] The aromatic polyamide is made from aramid fiber, which was purchased from Shanghai Tanlon Fiber Co., Ltd.

[0164] (3) The raw materials and process for preparing the slurry as described in (2) above are as follows:

[0165] S1.1, Prepare the suspension;

[0166] Specifically, in this experimental example: 0.18g of LLTO was added to 60g of NMP and ultrasonically dispersed for 1h to prepare the suspension.

[0167] S1.2 Prepare an aramid fiber solution (solid content 13%);

[0168] Specifically, in this experimental example, a 13% solids content aramid fiber solution can be prepared by the following method: 46g of calcium chloride is completely dissolved in 160g of NMP by stirring at 80℃ for 30min. Then, 31g of aromatic polyamide fiber is added to the NMP solution containing chloride salt, and the mixture is stirred at 80℃ for 4-6h until completely dissolved, yielding a solution with a solids content of 13% and a viscosity of 5620mPa. ·The solution of s aramid fiber (pale yellow and transparent) contains chloride salt and aromatic polyamide fiber in a ratio of 1.5:1.

[0169] S1.3, Prepare the adhesive solution;

[0170] Specifically, in this experimental example: 4.5g of PVDF-HFP powder was added to 100.7g of NMP and mechanically stirred at 500rpm for 40min. Then, 34.6g of aramid fiber solution with a solid content of 13% prepared in S1.2 was added and mechanically stirred at 600rpm for 60min to prepare a composite adhesive containing PVDF-HFP and PSA.

[0171] The polyvinylidene fluoride-hexafluoropropylene copolymer has a number average molecular weight of 500,000-600,000; the proportion of hexafluoropropylene copolymer in the polyvinylidene fluoride-hexafluoropropylene copolymer is 4 wt%.

[0172] S1.4, Obtain the slurry as described in (2) above;

[0173] Specifically, in this experimental example: the suspension prepared in S1.1 above is mixed with the adhesive prepared in S1.3 above, dispersed at high speed in an ice bath for 60 minutes, and then filtered through a 300-mesh filter. The lower layer of filtrate is taken to obtain the coating slurry.

[0174] (4) The process of preparing the diaphragm using the slurry described in (2) above is as follows:

[0175] The slurry described in (2) above (or the slurry prepared in (3) above) is uniformly coated on both sides of the polyethylene film described in (1) above using a No. 40 wire rod;

[0176] After coating, the membrane was first immersed in a coagulation tank with an NMP concentration of 45% for 3 minutes, then in a coagulation tank with an NMP concentration of 20% for 3 minutes, and then in a pure water tank for 3 minutes. The membrane was then immersed twice and finally dried in an oven at 60°C for 20 minutes to obtain a membrane with a thickness of 11 μm and a total coating thickness of 4 μm.

[0177] Experiment Example 4

[0178] (1) The diaphragm provided in this experimental example is shown in #4 of Table 1. The diaphragm is composed of a polyethylene base film and a coating on both sides of the base film.

[0179] Regarding the coating: the coating contains solid electrolyte LATP, aromatic polyamide, and polyvinylidene fluoride-hexafluoropropylene in a mass ratio of 0.18:6.3:2.7.

[0180] The coating has a thickness of 4 μm.

[0181] Regarding the aforementioned polyethylene-based film: it has a thickness of 7 μm and a porosity of 38%.

[0182] (2) The slurry used for preparing the diaphragm provided in this experimental example is as follows:

[0183] The slurry contains solid electrolyte LATP, aromatic polyamide, polyvinylidene fluoride-hexafluoropropylene, and solvent;

[0184] The solid contents of the slurry are 0.09% for the solid electrolyte LATP, 3.15% for aromatic polyamide, and 1.35% for polyvinylidene fluoride-hexafluoropropylene.

[0185] The mass ratio of solid electrolyte, aromatic polyamide and polyvinylidene fluoride-hexafluoropropylene in the slurry is 1:35:15;

[0186] The solvent is N-methylpyrrolidone.

[0187] The aromatic polyamide is made from aramid fiber, which was purchased from Shanghai Tanlon Fiber Co., Ltd.

[0188] (3) The raw materials and process for preparing the slurry as described in (2) above are as follows:

[0189] S1.1, Prepare the suspension;

[0190] Specifically, in this experimental example: 0.18g of LATP was added to 60g of NMP and ultrasonically dispersed for 1h to prepare the suspension.

[0191] S1.2 Prepare an aramid fiber solution (solid content 13%);

[0192] Specifically, in this experimental example, a 13% solids content aramid fiber solution can be prepared by the following method: 46g of calcium chloride is completely dissolved in 160g of NMP by stirring at 80℃ for 30min. Then, 31g of aromatic polyamide fiber is added to the NMP solution containing chloride salt, and the mixture is stirred at 80℃ for 4-6h until completely dissolved, yielding a solution with a solids content of 13% and a viscosity of 5620mPa. · The solution of s aramid fiber (pale yellow and transparent) contains chloride salt and aromatic polyamide fiber in a ratio of 1.5:1.

[0193] S1.3, Prepare the adhesive solution;

[0194] Specifically, in this experimental example: 2.7g of PVDF-HFP powder was added to 88.7g of NMP and mechanically stirred at 500rpm for 40min. Then, 48.5g of aramid fiber solution with a solid content of 13% prepared in S1.2 was added and mechanically stirred at 600rpm for 60min to prepare a composite adhesive containing PVDF-HFP and PSA.

[0195] The polyvinylidene fluoride-hexafluoropropylene copolymer has a number average molecular weight of 500,000-600,000; the proportion of hexafluoropropylene copolymer in the polyvinylidene fluoride-hexafluoropropylene copolymer is 4 wt%.

[0196] The raw material for the aromatic polyamide is aramid fiber, purchased from Shanghai Tanlon Fiber Co., Ltd.

[0197] S1.4, Obtain the slurry as described in (2) above;

[0198] Specifically, in this experimental example: the suspension prepared in S1.1 above is mixed with the gel prepared in S1.3 above, dispersed at high speed in an ice bath for 60 minutes, and then filtered through a 300-mesh filter. The lower layer of filtrate is taken to obtain the coating slurry.

[0199] (4) The process of preparing the diaphragm using the slurry described in (2) above is as follows:

[0200] The slurry described in (2) above (or the slurry prepared in (3) above) is uniformly coated on both sides of the polyethylene film described in (1) above using a No. 40 wire rod;

[0201] After coating, the membrane was first immersed in a coagulation tank with an NMP concentration of 45% for 3 minutes, then in a coagulation tank with an NMP concentration of 20% for 3 minutes, and then in a pure water tank for 3 minutes. The membrane was then immersed twice and finally dried in an oven at 60°C for 20 minutes to obtain a membrane with a thickness of 11 μm and a total coating thickness of 4 μm.

[0202] Experimental Example 5

[0203] (1) The diaphragm provided in this experimental example is shown in #5 of Table 1. The diaphragm is composed of a polyethylene base film and a coating on both sides of the base film.

[0204] Regarding the coating: the coating contains solid electrolyte LLZO, aromatic polyamide, and polyvinylidene fluoride-hexafluoropropylene in a mass ratio of 0.18:6.3:2.7.

[0205] The coating has a thickness of 4 μm.

[0206] Regarding the aforementioned polyethylene-based film: it has a thickness of 7 μm and a porosity of 38%.

[0207] (2) The slurry used for preparing the diaphragm provided in this experimental example is as follows:

[0208] The slurry contains solid electrolyte LLZO, aromatic polyamide, polyvinylidene fluoride-hexafluoropropylene, and solvent;

[0209] The solid contents of the solid electrolyte LLZO, aromatic polyamide, and polyvinylidene fluoride-hexafluoropropylene (PVDF-HFP) in the slurry are 0.09%, 3.15%, and 1.35%, respectively.

[0210] The mass ratio of solid electrolyte, aromatic polyamide and polyvinylidene fluoride-hexafluoropropylene in the slurry is 1:35:15;

[0211] The solvent is N-methylpyrrolidone.

[0212] The aromatic polyamide is made from aramid fiber, which was purchased from Shanghai Tanlon Fiber Co., Ltd.

[0213] (3) The raw materials and process for preparing the slurry as described in (2) above are as follows:

[0214] S1.1, Prepare the suspension;

[0215] Specifically, in this experimental example: 0.18g of LLZO was added to 60g of NMP and ultrasonically dispersed for 1h to prepare the suspension.

[0216] S1.2 Prepare an aramid fiber solution (solid content 13%);

[0217] Specifically, in this experimental example, a 13% solids content aramid fiber solution can be prepared by the following method: 46g of calcium chloride is completely dissolved in 160g of NMP by stirring at 80℃ for 30min. Then, 31g of aromatic polyamide fiber is added to the NMP solution containing chloride salt, and the mixture is stirred at 80℃ for 4-6h until completely dissolved, yielding a solution with a solids content of 13% and a viscosity of 5620mPa. · The solution of s aramid fiber (pale yellow and transparent) contains chloride salt and aromatic polyamide fiber in a ratio of 1.5:1.

[0218] S1.3, Prepare the adhesive solution;

[0219] Specifically, in this experimental example: 2.7g of PVDF-HFP powder was added to 88.7g of NMP and mechanically stirred at 500rpm for 40min. Then, 48.5g of aramid fiber solution with a solid content of 13% prepared in S1.2 was added and mechanically stirred at 600rpm for 60min to prepare a composite adhesive containing PVDF-HFP and PSA.

[0220] The polyvinylidene fluoride-hexafluoropropylene copolymer has a number average molecular weight of 500,000-600,000; the proportion of hexafluoropropylene copolymer in the polyvinylidene fluoride-hexafluoropropylene copolymer is 4 wt%.

[0221] The raw material for the aromatic polyamide is aramid fiber, purchased from Shanghai Tanlon Fiber Co., Ltd.

[0222] S1.4, Obtain the slurry as described in (2) above;

[0223] Specifically, in this experimental example: the suspension prepared in S1.1 above is mixed with the gel prepared in S1.3 above, dispersed at high speed in an ice bath for 60 minutes, and then filtered through a 300-mesh filter. The lower layer of filtrate is taken to obtain the coating slurry.

[0224] (4) The process of preparing the diaphragm using the slurry described in (2) above is as follows:

[0225] The slurry described in (2) above (or the slurry prepared in (3) above) is uniformly coated on both sides of the polyethylene film described in (1) above using a No. 40 wire rod;

[0226] After coating, the membrane was first immersed in a coagulation tank with an NMP concentration of 45% for 3 minutes, then in a coagulation tank with an NMP concentration of 20% for 3 minutes, and then in a pure water tank for 3 minutes. The membrane was then immersed twice and finally dried in an oven at 60°C for 20 minutes to obtain a membrane with a thickness of 11 μm and a total coating thickness of 4 μm.

[0227] Experimental Example 6

[0228] (1) The diaphragm provided in this experimental example is shown as #6 in Table 1, and the difference between the #6 diaphragm and the #1 diaphragm in Experiment 1 is only in the porosity of the polyethylene film: the porosity of the polyethylene film in this experimental example is 75%.

[0229] The rest is the same as in Experiment 1.

[0230] Experimental Example 7

[0231] (1) The diaphragm provided in this experimental example is shown in #7 of Table 1. The diaphragm is composed of a polyethylene base film and a coating on both sides of the base film.

[0232] Regarding the coating: the coating contains solid electrolyte LLTO, aromatic polyamide and polyvinylidene fluoride-hexafluoropropylene in a mass ratio of 0.18:6.3:2.7.

[0233] The coating has a thickness of 4 μm.

[0234] Regarding the aforementioned polyethylene-based film: it has a thickness of 7 μm and a porosity of 38%.

[0235] (2) The slurry used for preparing the diaphragm provided in this experimental example is as follows:

[0236] The slurry contains solid electrolyte LLTO, aromatic polyamide, polyvinylidene fluoride-hexafluoropropylene, and solvent;

[0237] The solid contents of the solid electrolyte LLTO, aromatic polyamide, and polyvinylidene fluoride-hexafluoropropylene in the slurry are 0.08%, 2.73%, and 1.17%, respectively.

[0238] The mass ratio of solid electrolyte, aromatic polyamide and polyvinylidene fluoride-hexafluoropropylene in the slurry is 1:35:15;

[0239] The raw material for the aromatic polyamide is an aramid fiber solution;

[0240] The solvent is N-methylpyrrolidone.

[0241] The aromatic polyamide is made from aramid fiber, which was purchased from Shanghai Tanlon Fiber Co., Ltd.

[0242] (3) The raw materials and process for preparing the slurry as described in (2) above are as follows:

[0243] S1.1, Prepare the suspension;

[0244] Specifically, in this experimental example: 0.18g of LLTO was added to 60g of NMP and ultrasonically dispersed for 1h to prepare the suspension.

[0245] S1.2 Prepare an aramid fiber solution (solid content 8%);

[0246] Specifically, in this experimental example, the aramid fiber solution can be prepared by the following method: 24g of calcium chloride is completely dissolved in 160g of NMP by stirring at 80℃ for 30min. Then, 16g of aromatic polyamide fiber is added to the NMP solution containing chloride salt, and the mixture is stirred at 80℃ for 4-6h until completely dissolved, yielding a solution with a solid content of 8% and a viscosity of 3899mPa. ·The solution of s aramid fiber (pale yellow and transparent) contains chloride salt and aromatic polyamide fiber in a ratio of 1.5:1.

[0247] S1.3, Prepare the adhesive solution;

[0248] Specifically, in this experimental example: 2.7g of PVDF-HFP powder was added to 88.7g of NMP and mechanically stirred at 500rpm for 40min. Then, 78.8g of aramid fiber solution with a solid content of 8% prepared in S1.2 was added and mechanically stirred at 600rpm for 120min to prepare a composite adhesive containing PVDF-HFP and PSA.

[0249] The polyvinylidene fluoride-hexafluoropropylene copolymer has a number average molecular weight of 500,000-600,000; the proportion of hexafluoropropylene copolymer in the polyvinylidene fluoride-hexafluoropropylene copolymer is 4 wt%.

[0250] S1.4, Obtain the slurry as described in (2) above;

[0251] Specifically, in this experimental example: the suspension prepared in S1.1 above is mixed with the gel prepared in S1.3 above, dispersed at high speed in an ice bath for 60 minutes, and then filtered through a 300-mesh filter. The lower layer of filtrate is taken to obtain the coating slurry.

[0252] (4) The process of preparing the diaphragm using the slurry described in (2) above is as follows:

[0253] The slurry described in (2) above (or the slurry prepared in (3) above) is uniformly coated on both sides of the polyethylene film described in (1) above using a No. 40 wire rod;

[0254] After coating, the membrane was first immersed in a coagulation tank with an NMP concentration of 45% for 3 minutes, then in a coagulation tank with an NMP concentration of 20% for 3 minutes, and then in a pure water tank for 3 minutes. The membrane was then immersed twice and finally dried in an oven at 60°C for 20 minutes to obtain a membrane with a thickness of 11 μm and a total coating thickness of 4 μm.

[0255] The diaphragm was scanned by electron microscopy, such as... Figure 1 As shown.

[0256] Experimental Example 8

[0257] (1) The diaphragm provided in this experimental example is shown in #8 of Table 1. The diaphragm is composed of a polyethylene base film and a coating on both sides of the base film.

[0258] Regarding the coating described in this experimental example: the coating contains solid electrolyte LLTO, aromatic polyamide and polyvinylidene fluoride-hexafluoropropylene in a mass ratio of 0.18:8.1:0.9.

[0259] The coating has a thickness of 4 μm.

[0260] Regarding the aforementioned polyethylene-based film: it has a thickness of 7 μm and a porosity of 38%.

[0261] (2) The slurry used for preparing the diaphragm provided in this experimental example is as follows:

[0262] The slurry contains solid electrolyte LLTO, aromatic polyamide, polyvinylidene fluoride-hexafluoropropylene, and solvent;

[0263] The solid contents of the solid electrolyte LLTO, aromatic polyamide (PSA), and polyvinylidene fluoride-hexafluoropropylene (PVDF-HFP) in the slurry are 0.09%, 4.05%, and 0.45%, respectively.

[0264] The mass ratio of solid electrolyte, aromatic polyamide and polyvinylidene fluoride-hexafluoropropylene in the slurry is 1:45:5;

[0265] The solvent is N-methylpyrrolidone.

[0266] The aromatic polyamide is made from aramid fiber, which was purchased from Shanghai Tanlon Fiber Co., Ltd.

[0267] (3) The raw materials and process for preparing the slurry as described in (2) above are as follows:

[0268] S1.1, Prepare the suspension;

[0269] Specifically, in this experimental example: 0.18g of LLTO was added to 60g of NMP and ultrasonically dispersed for 1h to prepare the suspension.

[0270] S1.2 Prepare an aramid fiber solution (solid content 13%);

[0271] Specifically, in this experimental example, a 13% solids content aramid fiber solution can be prepared by the following method: 46g of calcium chloride is completely dissolved in 160g of NMP by stirring at 80℃ for 30min. Then, 31g of aromatic polyamide fiber is added to the NMP solution containing chloride salt, and the mixture is stirred at 80℃ for 4-6h until completely dissolved, yielding a solution with a solids content of 13% and a viscosity of 5620mPa. · The solution of s aramid fiber (pale yellow and transparent) contains chloride salt and aromatic polyamide fiber in a ratio of 1.5:1.

[0272] S1.3, Prepare the adhesive solution;

[0273] Specifically, in this experimental example: 0.9g of PVDF-HFP powder was added to 76.6g of NMP and mechanically stirred at 500rpm for 40min. Then, 62.3g of aramid fiber solution with a solid content of 13% prepared in S1.2 was added and mechanically stirred at 600rpm for 60min to prepare a composite adhesive containing PVDF-HFP and PSA.

[0274] The polyvinylidene fluoride-hexafluoropropylene copolymer has a number average molecular weight of 500,000-600,000; the proportion of hexafluoropropylene copolymer in the polyvinylidene fluoride-hexafluoropropylene copolymer is 4 wt%.

[0275] S1.4, Obtain the slurry as described in (2) above;

[0276] Specifically, in this experimental example: the suspension prepared in S1.1 above is mixed with the adhesive prepared in S1.3 above, dispersed at high speed in an ice bath for 60 minutes, and then filtered through a 300-mesh filter. The lower layer of filtrate is taken to obtain the coating slurry.

[0277] (4) The process of preparing the diaphragm using the slurry described in (2) above is as follows:

[0278] The slurry described in (2) above (or the slurry prepared in (3) above) is uniformly coated on both sides of the polyethylene film described in (1) above using a No. 40 wire rod;

[0279] After coating, the membrane was first immersed in a coagulation tank with an NMP concentration of 45% for 3 minutes, then in a coagulation tank with an NMP concentration of 20% for 3 minutes, and then in a pure water tank for 3 minutes. The membrane was then immersed twice and finally dried in an oven at 60°C for 20 minutes to obtain a membrane with a thickness of 11 μm and a total coating thickness of 4 μm.

[0280] Experimental Example 9

[0281] (1) The diaphragm provided in this experimental example is shown in #9 of Table 1. The diaphragm is composed of a polyethylene base film and a coating on both sides of the base film.

[0282] Regarding the coating described in this experimental example: the coating contains solid electrolyte LLTO, aromatic polyamide and polyvinylidene fluoride-hexafluoropropylene in a mass ratio of 0.18:7.2:1.8.

[0283] The coating has a thickness of 4 μm.

[0284] Regarding the aforementioned polyethylene-based film: it has a thickness of 7 μm and a porosity of 38%.

[0285] (2) The slurry used for preparing the diaphragm provided in this comparative study is as follows:

[0286] The slurry contains solid electrolyte LLTO, aromatic polyamide, polyvinylidene fluoride-hexafluoropropylene, and solvent;

[0287] The slurry is basically the same as in Experiment 1, except that the solid contents of the solid electrolyte LLTO, aromatic polyamide and polyvinylidene fluoride-hexafluoropropylene (PVDF-HFP) in the slurry are 0.09%, 3.6% and 0.9%, respectively.

[0288] The mass ratio of solid electrolyte, aromatic polyamide and polyvinylidene fluoride-hexafluoropropylene in the slurry is 1:40:10;

[0289] The solvent is N-methylpyrrolidone.

[0290] The aromatic polyamide is made from aramid fiber, which was purchased from Shanghai Tanlon Fiber Co., Ltd.

[0291] (3) The raw materials and process for preparing the slurry as described in (2) above are as follows:

[0292] S1.1, Prepare the suspension;

[0293] Specifically, in this experimental example: 0.18g of LLTO was added to 60g of NMP and ultrasonically dispersed for 1h to prepare the suspension.

[0294] S1.2 Prepare an aramid fiber solution (solid content 13%);

[0295] Specifically, in this experimental example, a 13% solids content aramid fiber solution can be prepared by the following method: 46g of calcium chloride is completely dissolved in 160g of NMP by stirring at 80℃ for 30min. Then, 31g of aromatic polyamide fiber is added to the NMP solution containing chloride salt, and the mixture is stirred at 80℃ for 4-6h until completely dissolved, yielding a solution with a solids content of 13% and a viscosity of 5620mPa. · The solution of s aramid fiber (pale yellow and transparent) contains chloride salt and aromatic polyamide fiber in a ratio of 1.5:1.

[0296] S1.3, Prepare the adhesive solution;

[0297] Specifically, in this experimental example: 1.8g of PVDF-HFP powder was added to 82.6g of NMP and mechanically stirred at 500rpm for 40min. Then, 55.4g of aramid fiber solution with a solid content of 13% prepared in S1.2 was added and mechanically stirred at 600rpm for 60min to prepare a composite adhesive containing PVDF-HFP and PSA.

[0298] The polyvinylidene fluoride-hexafluoropropylene copolymer has a number average molecular weight of 500,000-600,000; the proportion of hexafluoropropylene copolymer in the polyvinylidene fluoride-hexafluoropropylene copolymer is 4 wt%.

[0299] S1.4, Obtain the slurry as described in (2) above;

[0300] Specifically, in this experimental example: the suspension prepared in S1.1 above is mixed with the adhesive prepared in S1.3 above, dispersed at high speed in an ice bath for 60 minutes, and then filtered through a 300-mesh filter. The lower layer of filtrate is taken to obtain the coating slurry.

[0301] (4) The process of preparing the diaphragm using the slurry described in (2) above is as follows:

[0302] The slurry described in (2) above (or the slurry prepared in (3) above) is uniformly coated on both sides of the polyethylene film described in (1) above using a No. 40 wire rod;

[0303] After coating, the membrane was first immersed in a coagulation tank with an NMP concentration of 45% for 3 minutes, then in a coagulation tank with an NMP concentration of 20% for 3 minutes, and then in a pure water tank for 3 minutes. The membrane was then immersed twice and finally dried in an oven at 60°C for 20 minutes to obtain a membrane with a thickness of 11 μm and a total coating thickness of 4 μm.

[0304] Experimental Example 10

[0305] (1) The diaphragm provided in this experimental example is shown as #10 in Table 1. The diaphragm is composed of a polyethylene base film and a coating on both sides of the base film.

[0306] Regarding the coating: the coating contains solid electrolyte LLTO, aramid 1313 fiber and polyvinylidene fluoride-hexafluoropropylene in a mass ratio of 0.18:6.3:2.7.

[0307] The total thickness of the double coating is 4 μm.

[0308] Regarding the aforementioned polyethylene-based film: it has a thickness of 7 μm and a porosity of 38%.

[0309] (2) The slurry used for preparing the diaphragm provided in this experimental example is as follows:

[0310] The slurry contains solid electrolyte LLTO, aramid 1313, polyvinylidene fluoride-hexafluoropropylene, and solvent;

[0311] The solid contents of the solid electrolyte LLTO, aramid 1313, and polyvinylidene fluoride-hexafluoropropylene in the slurry are 0.09%, 3.15%, and 1.35%, respectively.

[0312] The mass ratio of solid electrolyte, aramid 1313 and polyvinylidene fluoride-hexafluoropropylene in the slurry is 1:35:15.

[0313] The solvent is N-methylpyrrolidone.

[0314] The aromatic polyamide is made from aramid 1313 fiber, which was purchased from Zhongfang Special Fiber Co., Ltd. Meta-aramid short fibers.

[0315] (3) The raw materials and process for preparing the slurry as described in (2) above are as follows:

[0316] S1.1, Prepare the suspension;

[0317] Specifically, in this experimental example: 0.18g of LLTO was added to 60g of NMP and ultrasonically dispersed for 1h to prepare the suspension.

[0318] S1.2 Prepare an aromatic polyamide fiber solution (solid content 13%);

[0319] Specifically, in this experimental example, an aromatic polyamide fiber solution with a solid content of 13% (an aramid 1313 fiber solution with a solid content of 13%) can be prepared by the following method: 46g of calcium chloride is completely dissolved in 160g of NMP by stirring at 80℃ for 30min, and then 31g of aromatic polyamide fiber is added to the NMP solution containing chloride salt. The solution is stirred at 80℃ for 4-6h until completely dissolved to obtain an aramid 1313 fiber solution with a solid content of 13%, wherein the ratio of chloride salt to aromatic polyamide fiber is 1.5:1.

[0320] S1.3, Prepare the adhesive solution;

[0321] Specifically, in this experimental example: 2.7g of PVDF-HFP powder was added to 88.7g of NMP and mechanically stirred at 500rpm for 40min. Then, 48.5g of aramid 1313 fiber solution with a solid content of 13% prepared in S1.2 was added and mechanically stirred at 600rpm for 60min to prepare a composite adhesive containing PVDF-HFP and PSA.

[0322] The PVDF-HFP powder is the same as in Experimental Example 1.

[0323] The polyvinylidene fluoride-hexafluoropropylene copolymer has a number average molecular weight of 500,000-600,000; the proportion of hexafluoropropylene copolymer in the polyvinylidene fluoride-hexafluoropropylene copolymer is 4 wt%.

[0324] S1.4, Obtain the slurry as described in (2) above;

[0325] Specifically, in this experimental example: the suspension prepared in S1.1 above is mixed with the gel prepared in S1.3 above, dispersed at high speed in an ice bath for 60 minutes, and then filtered through a 300-mesh filter. The lower layer of filtrate is taken to obtain the coating slurry.

[0326] (4) The process of preparing the diaphragm using the slurry described in (2) above is as follows:

[0327] The slurry described in (2) above (or the slurry prepared in (3) above) is uniformly coated on both sides of the polyethylene film described in (1) above using a No. 40 wire rod;

[0328] After coating, the membrane was first immersed in a coagulation tank with an NMP concentration of 45% for 3 minutes, then in a coagulation tank with an NMP concentration of 20% for 3 minutes, and then in a pure water tank for 3 minutes. The membrane was then immersed twice and finally dried in an oven at 60°C for 20 minutes to obtain a membrane with a thickness of 11 μm and a total coating thickness of 4 μm.

[0329] Experimental Example 11

[0330] (1) The diaphragm provided in this experimental example is shown as #11 in Table 1, and the difference between the #11 diaphragm and the #10 diaphragm in Experimental Example 10 is only in the coating composition.

[0331] Regarding the coating: Calculated by mass ratio, the coating contains solid electrolyte LLTO, aramid 1414 fiber, and polyvinylidene fluoride-hexafluoropropylene, with the remainder being the same as in Experimental Example 10.

[0332] (2) The slurry used for preparing the diaphragm provided in this experimental example is as follows:

[0333] The slurry is the same as in Experimental Example 10, except that the aramid 1313 fiber in the slurry is replaced with aramid 1414 fiber, and the rest is the same as in Experimental Example 10.

[0334] (3) The raw materials and process for preparing the slurry as described in (2) above are as follows:

[0335] The raw materials and process for preparing the slurry are basically the same as in Experimental Example 10, except that the aramid 1313 fiber in the slurry is replaced with aramid 1414 fiber. The rest is the same as in Experimental Example 10. The aramid 1414 fiber was purchased from Zhongfangte Fiber Co., Ltd. Short fibers.

[0336] (4) The process of preparing the diaphragm using the slurry described in (2) above is as follows:

[0337] The preparation process of the diaphragm is basically the same as that of Experimental Example 10, except that the aramid 1313 fiber in the slurry is replaced with aramid 1414 fiber, and the rest is the same as that of Experimental Example 10.

[0338] Experimental Example 12

[0339] (1) The diaphragm provided in this experimental example is shown in #12 of Table 1. The diaphragm is composed of a polyethylene base film and a coating on both sides of the base film.

[0340] Regarding the coating: the coating contains solid electrolyte LLTO and polyvinylidene fluoride-hexafluoropropylene in a mass ratio of 0.18:2.7.

[0341] The coating has a thickness of 4 μm.

[0342] Regarding the aforementioned polyethylene-based film: it has a thickness of 7 μm and a porosity of 38%.

[0343] (2) The slurry used for preparing the diaphragm provided in this experimental example is as follows:

[0344] The slurry contains a solid electrolyte LLTO, polyvinylidene fluoride-hexafluoropropylene, and a solvent;

[0345] The solid electrolyte LLTO and the solid content of polyvinylidene fluoride-hexafluoropropylene in the slurry are 0.09% and 1.35%, respectively.

[0346] The mass ratio of solid electrolyte, aromatic polyamide and polyvinylidene fluoride-hexafluoropropylene in the slurry is 1:15.

[0347] The solvent is N-methylpyrrolidone.

[0348] (3) The raw materials and process for preparing the slurry as described in (2) above are as follows:

[0349] S1.1, Prepare the suspension;

[0350] Specifically, in this experimental example: 0.18g of LLTO was added to 60g of NMP and ultrasonically dispersed for 1h to prepare the suspension.

[0351] S1.2, Prepare the adhesive solution;

[0352] Specifically, in this experimental example: 2.7g of PVDF-HFP powder was added to 88.7g of NMP and mechanically stirred at 500rpm for 40min. Then, 48.5g of N-methylpyrrolidone prepared in S1.2 was added and mechanically stirred at 600rpm for 60min to prepare a PVDF-HFP composite adhesive.

[0353] The polyvinylidene fluoride-hexafluoropropylene copolymer has a number average molecular weight of 500,000-600,000; the proportion of hexafluoropropylene copolymer in the polyvinylidene fluoride-hexafluoropropylene copolymer is 4 wt%.

[0354] (4) The process of preparing the diaphragm using the slurry described in (2) above is as follows:

[0355] The slurry described in (2) above (or the slurry prepared in (3) above) is uniformly coated on both sides of the polyethylene film described in (1) above using a No. 40 wire rod;

[0356] After coating, the membrane was first immersed in a coagulation tank with an NMP concentration of 45% for 3 minutes, then in a coagulation tank with an NMP concentration of 20% for 3 minutes, and then in a pure water tank for 3 minutes. The membrane was then immersed twice and finally dried in an oven at 60°C for 20 minutes to obtain a membrane with a thickness of 11 μm and a total coating thickness of 4 μm.

[0357] Experimental Example 13

[0358] (1) The diaphragm provided in this experimental example is shown in #13 of Table 1. The diaphragm is composed of a polyethylene base film and a coating on both sides of the base film.

[0359] Regarding the coating described in this experimental example: the coating contains solid electrolyte LLTO and aromatic polyamide in a mass ratio of 0.18:6.3.

[0360] The coating has a thickness of 4 μm.

[0361] Regarding the aforementioned polyethylene-based film: it has a thickness of 7 μm and a porosity of 38%.

[0362] (2) The slurry used for preparing the diaphragm provided in this experimental example is as follows:

[0363] The slurry contains a solid electrolyte LLTO, an aromatic polyamide, and a solvent;

[0364] The solid electrolyte LLTO and aromatic polyamide in the slurry contain 0.09% and 3.15% solids, respectively.

[0365] The mass ratio of solid electrolyte, aromatic polyamide and polyvinylidene fluoride-hexafluoropropylene in the slurry is 1:35.

[0366] The solvent is N-methylpyrrolidone.

[0367] The aromatic polyamide is made from aramid fiber, which was purchased from Shanghai Tanlon Fiber Co., Ltd.

[0368] (3) The raw materials and process for preparing the slurry as described in (2) above are as follows:

[0369] S1.1, Prepare the suspension;

[0370] Specifically, in this experimental example: 0.18g of LLTO was added to 60g of NMP and ultrasonically dispersed for 1h to prepare the suspension.

[0371] S1.2 Prepare an aramid fiber solution (solid content 13%);

[0372] Specifically, in this experimental example, a 13% solids content aramid fiber solution can be prepared by the following method: 46g of calcium chloride is completely dissolved in 160g of NMP by stirring at 80℃ for 30min. Then, 31g of aromatic polyamide fiber is added to the NMP solution containing chloride salt, and the mixture is stirred at 80℃ for 4-6h until completely dissolved, yielding a solution with a solids content of 13% and a viscosity of 5620mPa. · The solution of s aramid fiber (pale yellow and transparent) contains chloride salt and aromatic polyamide fiber in a ratio of 1.5:1.

[0373] S1.3, Prepare the adhesive solution;

[0374] Specifically, in this experimental example: 91.4g of NMP was mechanically stirred at 500rpm for 40min, and then 48.5g of aramid fiber solution with a solid content of 13% prepared in S1.2 was added, and mechanically stirred at 600rpm for 60min to prepare PSA adhesive solution.

[0375] S1.4, Obtain the slurry as described in (2) above;

[0376] Specifically, in this experimental example: the suspension prepared in S1.1 above is mixed with the adhesive prepared in S1.3 above, dispersed at high speed in an ice bath for 60 minutes, and then filtered through a 300-mesh filter. The lower layer of filtrate is taken to obtain the coating slurry.

[0377] (4) The process of preparing the diaphragm using the slurry described in (2) above is as follows:

[0378] The slurry described in (2) above (or the slurry prepared in (3) above) is uniformly coated on both sides of the polyethylene film described in (1) above using a No. 40 wire rod;

[0379] After coating, the membrane was first immersed in a coagulation tank with an NMP concentration of 45% for 3 minutes, then in a coagulation tank with an NMP concentration of 20% for 3 minutes, and then in a pure water tank for 3 minutes. The membrane was then immersed twice and finally dried in an oven at 60°C for 20 minutes to obtain a membrane with a thickness of 11 μm and a total coating thickness of 4 μm.

[0380] The raw material formulations for Experimental Examples 1 to 13 above are shown in Table 1.

[0381] The composite separators prepared in Experiments 1-13 were assembled into batteries, and the impedance values ​​of each battery were tested to calculate the ionic conductivity of the separator. The remaining test methods and conditions are as follows. Specific test data are shown in Table 2.

[0382] Furthermore, the specific testing methods involved are as follows:

[0383] Adhesion strength test method: Fold the coated side of the diaphragm together and press them together. Then, use A4 paper to clamp the coated film and feed it into a preheated hot press (Qmesys, QM940AS) at 100℃ and a speed of 1. After the test, cut the sample using a 2.5cm×30cm tooling die. Finally, test the sample on a tensile testing machine (Jinan Siker Testing Technology Co., Ltd., TSL-1002) at a speed of 50mm / min. Take the average value of three tests.

[0384] Heat shrinkage rate test method: Cut the diaphragm into a 15×15cm square, mark 10cm in the MD direction and 10cm in the TD direction with a film ruler, cover it with two A4 sheets of paper, put it in a preheated oven at 130℃ for 1 hour, and then take it out to measure the heat shrinkage in the MD and TD directions.

[0385] Peel strength test method: Use a membrane cutter to cut a 2.5cm × 30cm sample along the MD direction of the diaphragm. Apply 3M (200MP) double-sided tape evenly to the peeling plate, and then carefully attach the prepared sample strip to the peeling plate with the coated side facing down. Do not touch the sample area with your hand. Roll the sample back and forth twice using the pressure roller (2kg) provided with the equipment (4 times for individual rolling). Finally, test the sample on a tensile testing machine (Jinan Sike Testing Technology Co., Ltd., TSL-1002) at a speed of 50mm / min. Take the average value of three tests.

[0386] Test method for film rupture temperature: TMA test is used, the test conditions are tensile force 0.03N, heating rate 5℃ / min, and termination temperature 600℃.

[0387] Table 1. Formulations of Experimental Examples 1-3 of the present invention (unit: g)

[0388]

[0389] Table 2. Membrane parameters obtained from Experimental Examples 1-13 of the present invention.

[0390]

[0391]

[0392] As can be seen from the above experimental examples, when the mass ratio of solid electrolyte, aromatic polyamide, and polyvinylidene fluoride in the battery separator coating of this application is 1:(20-35):(15-25), the separator of this application exhibits a small thermal shrinkage rate, a high membrane rupture temperature, high ionic conductivity, high adhesive strength, high peel strength, good porosity, and good membrane morphology retention under a treatment of 130℃ / 1h. In other words, it possesses good heat resistance stability, high safety, and high ionic conductivity, ensuring the safety, reliability, and durability of the battery. When the aromatic polyamide fiber is aramid 1313 fiber, although it has good ionic conductivity, its adhesive strength is poor, and its porosity is poor. When the aromatic polyamide fiber is aramid 1414 fiber, its heat resistance, ionic conductivity, and membrane morphology retention cannot meet the actual production requirements.

[0393] Furthermore, based on the separator provided by this invention, the separator can be applied to lithium-ion batteries.

Claims

1. A diaphragm, characterized in that The separator comprises: a base film; a coating layer on at least one side surface of the base film; wherein the coating layer contains a solid-state electrolyte, an aromatic polyamide, and a polyvinylidene fluoride; the mass ratio of the solid-state electrolyte, the aromatic polyamide, and the polyvinylidene fluoride is 1:(20-35):(15-25) according to the mass ratio.

2. The separator according to claim 1, characterized in that The thickness of the base film is 3-14 μm, and the porosity of the base film is 30%-90%; The thickness of the coating layer is 1-14 μm.

3. A method for the preparation of a diaphragm, characterized in that The method comprises the steps of: S1. preparing a slurry containing a solid-state electrolyte, an aromatic polyamide, a polyvinylidene fluoride raw material, and a solvent; the mass ratio of the solid-state electrolyte, the aromatic polyamide, and the polyvinylidene fluoride raw material in the slurry is 1:(20-35):(15-25); Meanwhile, the solid content of the solid-state electrolyte, the aromatic polyamide, and the polyvinylidene fluoride raw material in the slurry is 0.01-8%, 1-15%, and 2-10%, respectively; S2. preparing a separator: coating the slurry on a base film, soaking after the completion of the slurry coating, and drying to obtain a separator.

4. The method of claim 3, wherein the membrane is prepared by a method comprising: The number average molecular weight of the polyvinylidene fluoride raw material is 500-600 thousand.

5. The method of claim 4, wherein the membrane is prepared by a method comprising: The polyvinylidene fluoride raw material comprises one or both of polyvinylidene fluoride and polyvinylidene fluoride-hexafluoropropylene. The proportion of the hexafluoropropylene copolymer in the polyvinylidene fluoride-hexafluoropropylene is 2-6 wt%.

6. The method of claim 5, wherein the membrane is prepared by a method comprising: The aromatic polyamide comprises one or both of polyphenylene terephthalamide and poly-m-phenylene isophthalamide.

7. The method of claim 6, wherein the membrane is prepared by a method comprising: The aromatic polyamide comprises polyphenylene terephthalamide.

8. The method of claim 6, wherein the membrane is prepared by a method comprising: The step S1 comprises: S1.

1. preparing a suspension containing a solid-state electrolyte and a solvent; The addition mass concentration of the solid-state electrolyte is 0.09-5 wt%, preferably 0.1-3 wt%; S1.

2. preparing a glue solution containing an aromatic polyamide, a polyvinylidene fluoride raw material, and a solvent; The addition mass concentration of the aromatic polyamide is 1-10 wt%, preferably 2-8 wt%; The addition mass concentration of the polyvinylidene fluoride raw material is 0.1-10 wt%, preferably 0.1-8 wt%; S1.

3. mixing and dispersing the suspension and the glue solution to obtain the slurry; The use mass ratio of the suspension to the glue solution is 0.1-1.

9. The method of claim 8, wherein the membrane is prepared by a method comprising: The addition mass concentration of the aromatic polyamide is 2-8 wt%, and the addition mass concentration of the polyvinylidene fluoride raw material is 0.1-8 wt%.

10. The method of claim 6 to 9, characterized in that In step S2, the soaking treatment comprises: first, soaking 1-2 times with N-methyl pyrrolidone, and the single soaking time is 2-3 min; and then, soaking 1-6 times with pure water, and the single soaking time is 2-3 min.

11. A lithium battery characterized by The lithium battery contains the separator according to any one of claims 1-2 or the separator prepared by the method according to any one of claims 3-10.

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