Coating slurry, separator, method for manufacturing separator, and battery

Abstract

The present invention provides a coating slurry, a separator, a manufacturing method, and a battery. The coating slurry contains a solvent, an ultra-high heat-resistant polymer resin adhesive, an auxiliary adhesive, a cross-linking agent, and an inorganic filler as main components. The present invention has succeeded in improving the heat resistance and the film-breaking temperature of the separator with simple formulation and lower cost, and greatly improving the safety of the battery.

Description

Technical Field

[0001] The present invention relates to the field of battery separator technology, and particularly to a coating slurry used for coating a battery separator, a separator coated with the slurry, a method for manufacturing a separator, and a battery.

Background Art

[0002] A lithium battery separator is one of the four main assemblies in a lithium-ion battery, which separates the positive and negative electrodes in a lithium-ion battery, allows the passage of lithium ions, and plays a role in insulating electrons. The quality of the separator performance directly affects the performance of the lithium-ion battery and is one of the important factors for the development of lithium-ion batteries. Lithium-ion battery separators applied in the fields of HEV (Hybrid Electric Vehicle), EV (Electric Vehicle), and energy storage are required to have performances such as high heat resistance, low impedance, and high adhesion. affected important factor ones.

Summary of the Invention

Problems to be Solved by the Invention

[0003] The present invention organic solvent provides a coating slurry, a separator, a manufacturing method, and a battery in order to improve the heat resistance and breakdown temperature of a coated battery separator.

Means for Solving the Problems

[0004] According to a first aspect of the present invention, there is provided a coating slurry containing a solvent, an ultra-high heat-resistant polymer resin adhesive, an auxiliary adhesive, a crosslinking agent, and an inorganic filler as main components.

[0005] In some embodiments, the melting point of the ultra-high heat-resistant polymer resin adhesive is 200 °C or higher, the addition amount of the ultra-high heat-resistant polymer resin adhesive is 1 to 60 wt%, and the ultra-high heat-resistant polymer resin adhesive is selected from one or two of polyimide, oxy-diphthalic anhydride-based polyimide, hexafluoroisopropylidene diphthalic anhydride-based polyimide, benzophenone tetracarboxylic dianhydride-based polyimide, bismaleimide oligomer, and alkenyl-terminated polyimide oligomer.

[0006] In some embodiments, the addition amount of the auxiliary adhesive is 1 to 20 wt%, and the auxiliary adhesive is selected from one or more of acrylate-based polymers, polyacrylic acids, polyurethane acrylates, polysiloxane methacrylates, PVDF homopolymers, vinylidene fluoride-hexafluoropropylene copolymers, and vinylidene fluoride-tetrafluoroethylene-propylene terpolymers.

[0007] In some embodiments, the addition amount of the crosslinking agent is 0.001 to 6 wt%, and the crosslinking agent is selected from one or more of diethylenetriamine, ethylenediamine, 3,3'-dichloro-4,4'-diaminodiphenylmethane, metaphenylenediamine, diaminodiphenylmethane, Isopropyl thioxanthone ITX ) benzophenone, and ethyl p-dimethylaminobenzoate.

[0008] In some embodiments, the addition amount of the inorganic filler is 1 to 70 wt%, and the particle size of the inorganic filler is 0. 3 ~0.8 μm.

[0009] In some embodiments, the inorganic filler is Al 2 O 3 SiO 2 TiO 2 ZrO 2 selected from one or more of MgO, CaO, AlOOH, and SiC.

[0010] In some embodiments, The coating slurry is an organic solvent coating slurry front recorded coating The solid content of the coating slurry is 7 to 20 wt%.

[0011] In some embodiments, the solvent is N-methylpyrrolidone NMP ) is the solvent.

[0012] According to a second aspect of the present invention, a separator including the above-described coating slurry and a substrate is provided, the coating slurry is applied to at least one surface of the substrate, and an irradiation treatment with ultraviolet rays having set energy and wavelength is performed to obtain the ultraviolet cross-linked separator.

[0013] In some embodiments, the wavelength of the ultraviolet light used is in the range of 210 nm to 420 nm, the ultraviolet cross-linking time is 0.001 s to 10 s, and the irradiation light intensity is 50 mj / cm 2 or more

[0014] In some embodiments, the thickness of the substrate is 5 to 20 μm.

[0015] In some embodiments, the substrate is , including any one of a polyolefin microporous membrane, a polyimide microporous membrane, a nonwoven separator, a multilayer composite separator, a ceramic-coated separator, and a polymer-coated separator .

[0016] According to a third aspect of the present invention, a separator including the above-described coating slurry and a substrate is provided, the coating slurry is applied to at least one surface of the substrate, the membrane breakage temperature of the separator is greater than 180 °C, its breakdown voltage is greater than 2.1 KV, and the breakdown voltage per unit thickness is greater than 5.1 KV / mil.

[0017] In some embodiments, the Machine direction MD ) of membrane breakage temperature is greater than 210 °C, and its Transverse direction TD ) membrane breakage temperature is greater than 190 °C.

[0018] According to a fourth aspect of the present invention, it is a method for manufacturing the above-described separator, (1) Add a super high heat-resistant polymer resin adhesive of 60 wt% or less and an auxiliary adhesive of 1-20 wt% to a solvent, dissolve them sufficiently, then add 1-70 wt% of an inorganic filler and disperse it uniformly to obtain a preliminary mixed slurry. Add a cross-linking agent to the solvent and dissolve it completely to obtain a cross-linking agent solution. Add the cross-linking agent solution to , so that the content of the cross-linking agent is 0.001 - 6 wt% of the solid content of the preliminary mixed slurry the preliminary mixed slurry to obtain a slurry preparation step for obtaining a slurry, (2) A coating step of applying the prepared slurry to at least one surface of a substrate, (3) A phase transition step of immersing the separator obtained after coating in a coagulation tank containing a mixed solution of a first solvent and a non-solvent to perform a phase transition, (4) A drying step of washing and drying the product obtained in the above step (3) to obtain a composite separator after drying, (5) An ultraviolet cross-linking step of subjecting the composite separator to a cross-linking reaction by ultraviolet irradiation to obtain an ultraviolet cross-linked composite separator. A method for manufacturing the above-described separator is provided.

[0019] In some embodiments, the wavelength of the ultraviolet light used is in the range of 210 nm to 420 nm, the ultraviolet cross-linking time is 0.001 s to 10 s, and the irradiation light intensity is 50 mj / cm 2 or more.

[0020] In some embodiments, the proportion of the first solvent in the sum of the masses of the first solvent and the non-solvent is 20 - 30 wt%.

[0021] In some embodiments, the slurry preparation step further includes adding an ultra-high heat-resistant polymer resin adhesive and an auxiliary adhesive to an NMP solvent, and continuously stirring at a temperature of 50 to 70 °C for 12 h to 24 h to obtain a preliminary mixed slurry

[0022] According to the fifth aspect of the present invention, a battery including a separator, a positive electrode, a negative electrode, and an electrolyte is provided, and the separator is the above-described separator.

Advantages of the Invention

[0023] Compared with the prior art, the present invention has at least the following technical effects. Succeeded in improving the heat resistance and breakdown temperature of the separator with a simple formulation and process at a lower cost, significantly improving the safety of the battery.

Brief Description of the Drawings

[0024] The present invention will be further described below with reference to the drawings and specific embodiments.

Figure 1

Modes for Carrying Out the Invention

[0025] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative labor shall fall within the protection scope of the present invention.

[0026] Before filing this application, the applicant conducted a series of studies and experiments on conventional separators.

[0027] Among them, in order to ensure heat resistance, Ceramic coating separator CCS ) + Non-solvent induced phase separation NIPS ) Adopt a manufacturing process by layer-by-layer coating, that is, first, in order to ensure its heat resistance, Polypropylene PP ) Or apply a ceramic layer on one or both sides of a PE or PP / PE / PP base film, and then apply an adhesive resin coating to the ceramic layer to meet its adhesion performance. However, the production process of the layer-by-layer coating process is complex and is disadvantageous for cost control and production management.

[0028] It is a method of oil-based mixed coating, that is, high heat resistance resin adhesive(For example, polyetherimide) and a photoinitiator are selected and applied to the base film, and then UV crosslinking is performed. However, the conventional oil-based mixed coating process has inferior heat resistance compared to layer-by-layer coating. Through experimental verification and analysis, the applicant discovered that the heat resistance of the oil-based mixed coating process is inferior because the main chain of resin adhesive itself is stable, resulting in a poor crosslinking effect. resin adhesive Since the main chain of resin adhesive itself is stable, the applicant discovered that the heat resistance of the oil-based mixed coating process is inferior due to the poor crosslinking effect.

[0029] To solve the problem of inferior heat resistance of the oil-based mixed coating, the applicant conducted a series of theoretical studies and experimental verifications. For example, the applicant tried to replace the conventional high heat resistance resin adhesive with ultra-high heat resistance resin adhesive (for example, polyetherimide), but the improvement in heat resistance was not obvious. resin adhesive with ultra-high heat resistance resin adhesive (For example, polyetherimide), but the improvement in heat resistance was not obvious.

[0030] As a further research form, the applicant replaced the conventional high heat resistance resin adhesive with ultra-high heat resistance resin adhesive (for example, polyetherimide) and added ceramic fillers to further improve the heat resistance. However, in the actual process, it was found that it was difficult to complete this with the conventional organic solvent coating process. After a series of analyses and experiments, it was found that when polyetherimide is applied to the base film after dissolution, its adhesion is poor, and in the the above steps coating process, immersion in the coagulation tank is required. During the immersion process, polyetherimide falls off, which is the reason for affecting the final product performance. resin adhesive with ultra-high heat resistance resin adhesive (For example, polyetherimide), and ceramic fillers were added to further improve the heat resistance. However, in the actual process, it was found that it was difficult to complete this with the conventional organic solvent coating process. After a series of analyses and experiments, it was found that when polyetherimide is applied to the base film after dissolution, its adhesion is poor, and in the the above steps coating process, immersion in the coagulation tank is required. During the immersion process, polyetherimide falls off, which is the reason for affecting the final product performance. organic solvent coating process the above steps It was found that the adhesion was poor when polyetherimide was applied to the base film after dissolution, and in the the above steps coating process, immersion in the coagulation tank was required. During the immersion process, polyetherimide fell off, which was found to be the reason for affecting the final product performance. organic solvent In the coating process, immersion in the coagulation tank is required. During the immersion process, polyetherimide falls off, which is the reason for affecting the final product performance.

[0031] Therefore, the technical solution of this application is obtained after considering the above problems of the oil-based mixed coating process and conducting a series of studies and experiments. The purpose is to solve how to improve the heat resistance of the separator manufactured by the oil-based mixed coating process and how to avoid the problem of falling off during the process of immersing the slurry to be coated in the coagulation tank.

[0032] The technical solution of the present invention will be described in detail below using specific examples. Several of the following specific examples can be combined with each other, and for the same or similar concepts or processes, the description may be omitted in some examples.

[0033] Embodiments of the present invention first provide a coating slurry containing a solvent, a super high heat-resistant polymer resin adhesive, an auxiliary adhesive, a crosslinking agent, and an inorganic filler as main components.

[0034] The melting point of the super high heat-resistant polymer resin adhesive may be 200°C or higher, the addition amount of the super high heat-resistant polymer resin adhesive may be 1 to 60 wt%, and the super high heat-resistant polymer resin adhesive may be polyimide, oxydiphthalic anhydride-based polyimide, hexafluoroisopropylidene diphthalic anhydride-based polyimide, benzophenone tetracarboxylic dianhydride-based polyimide, bismaleimide oligomer, or alkenyl-terminated polyimide oligomer. More preferably, the addition amount of the super high heat-resistant polymer resin adhesive may be 15 to 60 wt%.

[0035] For example, the addition amount of the super high heat-resistant polymer resin adhesive may be any point value among 1 wt%, 5 wt%, 8 wt%, 15 wt%, 20 wt%, 25 wt%, 28 wt%, 30 wt%, 33 wt%, 38 wt%, 43 wt%, 47 wt%, 50 wt%, 56 wt%, 58 wt%, 60 wt% or or within the range between any two point values.

[0036] The adhesive is one of the important materials that must be used to form the coating layer, and its selection and use have a significant impact on the adhesiveness, heat resistance, and electrochemical performance of the lithium-ion battery separator. For a long time, polyvinylidene fluoride (PVDF) has always been an important adhesive used in the battery industry and is also the most commonly used adhesive in lithium-ion batteries. By the way, the increasingly urgent cleaner production requirementWith the requirements for battery performance accompanied by the rapid application of high-performance power, the problems and deficiencies existing in the use of polyvinylidene fluoride (PVDF) adhesives are becoming increasingly apparent day by day. High-performance adhesives have become an important research direction for one of the main materials of lithium-ion batteries.

[0037] Different from the conventional polymer resin adhesives (the melting point is generally 130 - 160 °C), the ultra-high heat-resistant polymer resin adhesive of the present application not only has ultra-strong adhesiveness, but also has ultra-high heat resistance and good electrochemical performance. In order to comprehensively meet these performance requirements, the present application selects one or two of polyimide, oxydiphthalic anhydride-based polyimide, hexafluoroisopropylidene diphthalic anhydride-based polyimide, benzophenone tetracarboxylic dianhydride-based polyimide, bismaleimide oligomer, and alkenyl-terminated polyimide oligomer.

[0038] In order to prevent the problem of dropping during the process of immersion in the coagulation bath due to poor adhesion when an ultra-high heat-resistant polymer resin adhesive such as polyimide is applied to the base film, an auxiliary adhesive is added to the coating slurry of the present application. Here, the addition amount of the auxiliary adhesive may be 1 - 20 wt%, and the auxiliary adhesive is selected from one or more of acrylate-based polymers, polyacrylic acids, polyurethane acrylates, polysiloxane methacrylates, PVDF homopolymers, vinylidene fluoride - hexafluoropropylene copolymers, and vinylidene fluoride - tetrafluoroethylene - propylene terpolymers. With these auxiliary adhesives selected by the present application, the coating high has heat resistance, high adhesiveness, and appropriate swelling properties, and active groups that are prone to ultraviolet cross-linking and grafting actions are in the slurry system preparationIt becomes more stable. And since these auxiliary adhesives of the present application contain unsaturated double bonds, they can provide unsaturated double bonds, and thus can be effectively blended with the above-mentioned ultra-high heat-resistant polymer resin adhesive of the present application. Under the excitation of ultraviolet light, UV light can be generated to cure and crosslink active groups, thereby effectively generating grafting and crosslinking effects.

[0039] More preferably, the addition amount of the auxiliary adhesive may be 7 to 19 wt%.

[0040] For example, the addition amount of the auxiliary adhesive is any point value among 1 wt%, 5 wt%, 7 wt%, 8 wt%, 10 wt%, 15 wt%, 17 wt%, 18 wt%, 20 wt% or It may be in the range between any two point values.

[0041] The addition amount of the crosslinking agent may be 0.001 to 6 wt%. The crosslinking agent is selected from one or more of diethylenetriamine, ethylenediamine, 3,3'-dichloro-4,4'-diaminodiphenylmethane, metaphenylenediamine, diaminodiphenylmethane, ITX, benzophenone, ethyl p-dimethylaminobenzoate. The addition amount of the crosslinking agent is closely related to the performance of the separator. If the addition amount of the crosslinking agent is too small, the degree of crosslinking and curing will be insufficient, and it may not be possible to achieve the improvement of the desired film-breaking temperature. If the addition amount of the crosslinking agent is too large, it will remain excessively in the separator and cause an increase in cost. More preferably, the addition amount of the crosslinking agent is 0.01 to 5 wt%.

[0042] For example, the addition amount of the crosslinking agent is any point value among 0.01 wt%, 0.05 wt%, 0.07 wt%, 0.1 wt%, 0.5 wt%, 0.9 wt%, 1 wt%, 1.3 wt%, 1.7 wt%, ~19 wt%, 2.1 wt%, 2.5 wt%, 2.9 wt%, 3.1 wt%, 3.5 wt%, 3.9 wt%, 4.1 wt%, 4.5 wt%, 4.9 wt%, 5.1 wt%, 5.5 wt%, 5.9 wt%, 6 wt% orIt is within the range between any two point values.

[0043] Here, the addition amount of the inorganic filler may be 1 to 70 wt%, and the particle size of the inorganic filler is 0.3 to 0.8 μm. In some specific embodiments, the inorganic filler may be ceramic particles. It should be understood that the particle size of the filler referred to in the present application means the particle size of the secondary particles of the inorganic filler.

[0044] In some embodiments, the inorganic filler is Al 2 O 3 , SiO 2 , TiO 2 , ZrO 2 , MgO, CaO, AlOOH, SiC, selected from one or more of them.

[0045] More preferably, the addition amount of the inorganic filler is 10 to 70 wt%. For example, the addition amount of the inorganic filler is 10 wt%, 15 wt%, 20 wt%, 25 wt%, 30 wt%, 32 wt%, 35 wt%, 40 wt%, 45 wt%, 50 wt%, 55 wt%, 57 wt% - 60 wt% 、6 5 wt%, 70 wt%, any point value among them or It is within the range between any two point values.

[0046] In the present application, by adding an inorganic filler and uniformly dispersing and arranging it in the coating, better uniform heat transfer can be ensured.

[0047] In some embodiments, the organic solvent solid content of the coating slurry is 7 to 20 wt%. For example, the organic solvent solid content of the coating slurry is 7 wt%, 8 wt%, 9 wt%, 10 wt%, 11 wt%, 12 wt%, 13 wt%, 14 wt%, 15 wt%, 16 wt%, 17 wt%, 18 wt%, 19 wt%, 20 wt%, any point value among them or It may be within the range between any two point values.

[0048] In some embodiments, the solvent is NMP solvent.

[0049] The present invention further provides a separator comprising the above-mentioned coating slurry and a substrate, the coating slurry being applied to at least one surface (which may be one or both surfaces) of the substrate, and an ultraviolet ray irradiation treatment having set energy and wavelength is performed to obtain the separator that has been ultraviolet cross-linked.

[0050] The substrate is po These include, but are not limited to, microporous polyolefin membranes (polyethylene, polypropylene, polybutylene, etc.), microporous polyimide membranes, nonwoven fabric separators, multilayer composite separators, ceramic-coated separators, polymer-coated separators, etc. The thickness of the substrate is 5 to 20 μm.

[0051] In the ultraviolet irradiation process of the separator of the present invention, the crosslinking agent in the slurry can transition from the ground state to an excited state by the irradiation of ultraviolet light with a set wavelength and energy, and at the same time, it takes away H ions from the CH structure in the organic matter in the system and generates organic polymer radicals. When they are terminated, the organic polymer crosslinks, and generates molecular chain grafting and polymerization between the inorganic filler surface active group and the ultra-high heat resistant polymer resin adhesive and between the molecules of the ultra-high heat resistant polymer resin adhesive itself to form a uniform polymer network structure. The uniform distribution of the inorganic filler greatly ensures the uniform and rapid transfer of heat, and creates a synergistic effect with the crosslinked network structure of the ultra-high heat resistant polymer resin adhesive, greatly improving the overall heat resistance of the separator, and the heat shrinkage rate at 150°C*30min is less than 10%. In addition, the separator obtained by the present application has a better film rupture temperature, which is about 150°C for the conventional product, and the film rupture temperature of the product of the present invention is 180°C or higher. The safety performance of the product is further improved.

[0052] Referring to FIG. 1, as shown in FIG. 1, the present invention further provides a method for manufacturing the separator described above, the method comprising: Add a super high heat-resistant polymer resin adhesive of 60 wt% or less and an auxiliary adhesive of 1 to 20 wt% to a solvent, and after fully dissolving, add 1 to 60 wt% of an inorganic filler and disperse it uniformly to obtain a preliminary mixed slurry. Add a crosslinking agent to the solvent and completely dissolve it to obtain a crosslinking agent solution. Add the crosslinking agent solution to , so that the content of the cross-linking agent is 0.001 to 6 wt% of the solid content of the preliminary mixed slurry the preliminary mixed slurry to obtain a slurry, which is a slurry preparation step S1; A coating step S2 of coating the prepared slurry on at least one surface of the substrate; A phase transition step S3 of immersing the separator obtained after coating in a coagulation tank containing a mixed solution of a first solvent and a non-solvent to perform a phase transition; A drying step S4 of washing and drying the product obtained in the above step S3, and obtaining a composite separator after drying; An ultraviolet crosslinking step S5 of subjecting the composite separator to a crosslinking reaction by irradiation with ultraviolet rays to obtain an ultraviolet crosslinked composite separator.

[0053] In some preferred embodiments, the wavelength of the ultraviolet rays used is in the range of 210 nm to 420 nm, the ultraviolet crosslinking time is 0.001 s to 10 s, and the irradiation light intensity is 50 mj / cm 2 or more.

[0054] In some preferred embodiments, the proportion of the first solvent in the sum of the masses of the first solvent and the non-solvent is 20 to 30 wt%.

[0055] The present invention further provides a separator including the foregoing coating slurry and a substrate, the coating slurry is coated on at least one surface of the substrate, the film-breaking temperature of the separator is greater than 190 °C, its breakdown voltage is greater than 2.1 KV, and the breakdown voltage per unit thickness is greater than 5.1 KV / mil.

[0056] In some embodiments, the film-breaking temperature of the separator in the MD direction is greater than 210 °C, and its film-breaking temperature in the TD direction is greater than 190 °C.

[0057] Regarding the performance of the separator provided by the present invention, Table 1 can be specifically referred to.

[0058] The present invention provides a battery including a separator, a positive electrode, a negative electrode, and an electrolyte, wherein the separator is the separator described above.

[0059] Hereinafter, the performance of products according to some embodiments of the present invention will be analyzed by experiments.

[0060] Example 1 In the slurry preparation of S1, an ultra-high heat-resistant polymer resin adhesive and an auxiliary adhesive are added to an NMP solvent, and stirring is continuously carried out at a temperature of 50 to 70 ° C for 12 to 24 hours to obtain a preliminary mixed slurry A. After the polymer in the preliminary mixed slurry A is completely dissolved, an inorganic filler (particle size D50 = 0.3 to 0.8 μm) is added to the preliminary mixed slurry A, and stirring is carried out sufficiently at a temperature of 30 to 50 ° C and a stirring speed of 1800 rpm / min for 120 minutes to obtain a uniformly mixed and dispersed preliminary mixed slurry B. Further, a cross-linking agent is added to the NMP solvent and completely dissolved to obtain a cross-linking agent solution with a concentration of 20%, and the cross-linking agent solution is added to the preliminary mixed slurry B at an addition amount of 3 wt%. , total Solid content is 12% is A slurry is obtained. In the coating of S2, the prepared slurry is coated on at least one surface of the substrate. Specifically, a PE wet separator is prepared as the substrate, and the prepared slurry is coated on two opposite surfaces of the substrate using a micro concave roller, and the coating speed is 60 m / min. In the phase transition of S3, the separator obtained after coating is immersed in a coagulation tank containing a mixed solution of a first solvent and a non-solvent at a temperature of 25 ° C to perform a phase transition. Here, the proportion of the first solvent in the sum of the masses of the first solvent and the non-solvent is 25 wt%. In the drying of S4, the product obtained in the above step S3 is washed and dried to obtain a composite separator after drying. In the UV crosslinking of S5, the composite separator is subjected to a crosslinking reaction by irradiation with ultraviolet light to obtain a UV crosslinked composite separator. The wavelength of the ultraviolet light used is in the range of 250 nm to 390 nm, the UV crosslinking time is 0.6 s, and the irradiation light intensity reaches at least 50 mj / cm 2 . Here, of the entire production line the speed is 30 m / min.

[0061] Here, the wavelength of the ultraviolet light varies within a certain range. Therefore, in other embodiments, the ultraviolet light may be in a range value such as 210 - 310 nm, 250 - 390 nm, 280 - 420 nm, etc. When the wavelength range value is specified, the UV crosslinking time and the irradiation light intensity have a great influence on the crosslinking effect. Since the inorganic particles contained in the formulation have a certain shielding effect on ultraviolet light, when the ultraviolet light intensity is less than 50 mj / cm 2 , the crosslinking effect is poor.

[0062] In the example, the ultra-high heat-resistant polymer resin adhesive used is polyetherimide, the auxiliary adhesive is polyurethane acrylate, the inorganic filler is aluminum oxide ceramic powder, and the crosslinking agent is ITX. Here, the mass ratio of the ultra-high heat-resistant polymer resin adhesive : auxiliary adhesive : inorganic filler used is 60 : 8 : 32. The thickness of the substrate is 10.4 μm.

[0063] Example 2 Different from Example 1, in Example 2, the mass ratio of the ultra-high heat-resistant polymer resin adhesive : auxiliary adhesive : inorganic filler used is 25 : 8 : 57, and the thickness of the substrate is 11.9 μm. Other points of Example 2 are the same as those of Example 1, and the description is omitted here.

[0064] Example 3 Different from Example 1, in Example 3, the auxiliary adhesive used is Polyvinylidene fluoride-hexafluoropropylene copolymer P(VDF-HFP) )and the crosslinking agent is diethylenetriamine, where the mass ratio of the ultra-high heat-resistant polymer resin adhesive: auxiliary adhesive: inorganic filler used is 25:10:65, and the thickness of the base material is 11.7 μm. Other points of Example 3 are the same as those of Example 1, and the description is omitted here.

[0065] Example 4 Different from Example 1, in Example 4, the auxiliary adhesive used is P(VDF-HFP), the crosslinking agent is diethylenetriamine, where the mass ratio of the ultra-high heat-resistant polymer resin adhesive: auxiliary adhesive: inorganic filler used is 25:18:57, and the thickness of the base material is 11.8 μm. Other points of Example 4 are the same as those of Example 1, and the description is omitted here.

[0066] Example 5 Different from Example 1, in Example 5, the auxiliary adhesive used is P(VDF-HFP), the crosslinking agent is diethylenetriamine, where the mass ratio of the ultra-high heat-resistant polymer resin adhesive: auxiliary adhesive: inorganic filler used is 60:8:32, and the thickness of the base material is 11.6 μm. Other points of Example 5 are the same as those of Example 1, and the description is omitted here.

[0067] Example 6 Different from Example 1, in Example 6, the crosslinking agent is ITX + diethylenetriamine, where the mass ratio of the ultra-high heat-resistant polymer resin adhesive: auxiliary adhesive: inorganic filler used is 25:8:57, and the thickness of the base material is 11.7 μm. Other points of Example 6 are the same as those of Example 1, and the description is omitted here.

[0068] Example 7 Different from Example 1, in Example 7, the one used ultra-high heat-resistant polymer resin adhesiveis polyetherimide + bismaleimide, the auxiliary adhesive is P(VDF-HFP), the crosslinking agent is ITX + diethylenetriamine. Here, the mass ratio of the ultra-high heat-resistant polymer resin adhesive : auxiliary adhesive : inorganic filler used is 10:20:70, and the thickness of the substrate is 12 μm. Other points of Example 7 are the same as those of Example 1, and the description is omitted here.

[0069] Example 8 Different from Example 1, in Example 8, the ultra-high heat-resistant polymer resin adhesive is polyetherimide + bismaleimide, the auxiliary adhesive is P(VDF-HFP), and the crosslinking agent is ITX + diethylenetriamine. Here, the mass ratio of the ultra-high heat-resistant polymer resin adhesive : auxiliary adhesive : inorganic filler used is 55:15:30, and the thickness of the substrate is 12 μm. Other points of Example 8 are the same as those of Example 1, and the description is omitted here.

[0070] Comparative Example 1 Different from Example 1, in Comparative Example 1, instead of the ultra-high heat-resistant polymer resin adhesive of Example 1, P(VDF-HFP) is used. Here, the mass ratio of P(VDF-HFP) : auxiliary adhesive : inorganic filler used is 60:8:32, and the thickness of the substrate is 10.6 μm. Other points of Comparative Example 1 are the same as those of Example 1, and the description is omitted here.

[0071] Comparative Example 2 Different from Example 1, in Comparative Example 2, no auxiliary adhesive is added. Here, the mass ratio of the ultra-high heat-resistant polymer resin adhesive : auxiliary adhesive : inorganic filler used is 60: / :40, and the thickness of the substrate is 12 μm. Other points of Comparative Example 2 are the same as those of Example 1, and the description is omitted here.

[0072] Referring to Table 1, Table 1 shows the performance of the corresponding separators obtained in the above Examples 1 to 6 and Comparative Examples 1 to 2.

[0073] Here, the heat shrinkage test method at 150°C for 30 minutes is as follows. First, cut the separator into test samples with a size of 50 mm * 50 mm along the horizontal and vertical directions of the separator. add an initial mark Next, sandwich the cut samples between A4 papers, lay 5 A4 papers on the upper layer and 5 on the lower layer so that there are 5 on the top and 5 on the bottom. Subsequently, set the oven temperature to 150°C, preheat it sufficiently to ensure that the temperature rises to the set temperature and its internal temperature reaches the set temperature. Furthermore, quickly put the prepared samples sandwiched between A4 papers into the oven together with the A4 papers, place them at the middle position of the upper layer of the oven without putting the samples into the lower layer of the oven, immediately close the oven door. After closing the oven door, set the test time to 30 minutes according to the test requirements. When the time is up, take out the sample film from the oven. After it cools down to room temperature, gently spread the film, measure the distance between the edges of the separator in the horizontal / vertical direction, record the data, calculate the heat shrinkage rate, and the calculation formula for the heat shrinkage rate is: heat shrinkage rate % = (initial mark of between of length - mark after heating of between of length) / initial mark of between of length × 100%.

[0074] The film break temperature is Thermomechanical analysis obtained by testing with ) TMA. The test of the film break temperature by TMA is to pull the separator with a certain force (simulating the state inside the battery), and then gradually increase the temperature until the film breaks.

[0075] The adhesion performance of the electrode sheet refers to the test situation of the adhesion force of the separator to the electrode sheets on the two opposite sides, and the test method for the adhesion performance of the electrode sheet is as follows. The coating film sample to be measured is made into a standard strip sample (coating film (25mm * 180mm), electrode sheet (20mm * 150mm)). The separator coating surface and the electrode sheet are adhered using a hot press forming machine at a constant pressure and a temperature of 60°C. Subsequently, the other ends of the electrode sheet and the sample are clamped using a clamp, and a tensile force is applied until the stroke of the tensile machine ends. The parameters of the tensile machine are set to a fixed displacement of 150mm and a test speed of 300mm / min.

[0076] break The test method for the breakdown voltage is as follows. TH9320 withstand voltage tester broken by Perform a breakdown voltage test, and set the parameters to an output voltage of 6KV, an output current of 1mA, and a rise time of 30s. Gently place the copper conductor on the separator sample, and click the START start button. Then the device will start the test and automatically record the data.

[0077] The calculation method for the breakdown voltage per unit thickness is the breakdown voltage per unit thickness = broken Breakdown voltage (KV) * 25.4 / Separator thickness (μm) (here, 1mil = 25.4μm).

[0078]

Table 1

[0079] As can be seen from Table 1, this application significantly improves the overall heat resistance of the separator. The heat shrinkage rate of Examples 1 to 8 at 150°C * 30min is less than 10%, while the heat shrinkage rate of Comparative Example 1 and Comparative Example 2 at 150°C * 30min far exceeds 10%. Also, this application oil by Sex mixed coating obtained by the process The high heat-resistant and high-adhesion lithium-ion battery separator has an even better film-breaking temperature. The film-breaking temperatures of Examples 1 to 8 are all 180°C or higher, further improving the safety performance of the product. The film-breaking temperatures of Comparative Example 1 and Comparative Example 2 are both less than 180°C.

[0080] Here, ITX mainly plays a role in exciting active groups for polyurethane acrylate-based substances, generating graft cross-linking. The diamine-based mainly plays a role in exciting active groups for polyetherimide, and further generates bond cleavage, grafting, and cross-linking. When both exist simultaneously, their cross-linking effect is enhanced (for example, Example 6). Since there is a certain difference in the thickness of the separator, here the breakdown voltage per unit thickness of 1 mil is used to represent the improvement in breakdown voltage performance (1 mil = 25.4 μm).

[0081] In the description of this specification, the description referring to terms such as "one embodiment", "one example", "specific implementation process", "one example", etc. means that the specific features, structures, materials, or characteristics described in accordance with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic description of the above terms does not necessarily refer to the same embodiment or example. Moreover, the described specific features, structures, materials, or characteristics can be combined in a suitable manner in any one or more embodiments or examples.

[0082] It should be noted that the above examples are used to explain the technical solutions of the present invention and do not limit it. Although the present invention has been described in detail with reference to the above examples, those skilled in the art can still modify the technical solutions described in the above examples, or equivalently replace some or all of the technical features therein. It will be understood that these modifications or replacements do not deviate from the essence of the corresponding technical solutions from the scope of the technical solutions of each embodiment of the present invention.

Claims

1. A coating slurry comprising, as main components, a solvent, a super high heat-resistant polymer resin adhesive, an auxiliary adhesive, a crosslinking agent, and an inorganic filler. The coating slurry is characterized by the above.

2. The melting point of the super high heat-resistant polymer resin adhesive is 200°C or higher, the addition amount of the super high heat-resistant polymer resin adhesive is 1 to 60 wt%, and the super high heat-resistant polymer resin adhesive is selected from one or two of polyimide, an oxydiphthalic anhydride-based polyimide, a hexafluoroisopropylidene diphthalic anhydride-based polyimide, a benzophenone tetracarboxylic dianhydride-based polyimide, a bismaleimide oligomer, and an alkenyl-terminated polyimide oligomer. The coating slurry according to Claim 1, characterized by the above.

3. The addition amount of the auxiliary adhesive is 1 to 20 wt%, and the auxiliary adhesive is selected from one or more of an acrylate-based polymer, polyacrylic acid, polyurethane acrylate, polysiloxane methacrylate, a PVDF homopolymer, a vinylidene fluoride - hexafluoropropylene copolymer, and a vinylidene fluoride - tetrafluoroethylene - propylene terpolymer. The coating slurry according to Claim 1 or 2, characterized by the above.

4. The addition amount of the crosslinking agent is 0.001 to 6 wt%, and the crosslinking agent is selected from one or more of diethylenetriamine, ethylenediamine, 3,3'-dichloro - 4,4'-diaminodiphenylmethane, metaphenylenediamine, diaminodiphenylmethane, ITX, benzophenone, and ethyl p-dimethylaminobenzoate. The coating slurry according to Claim 1 or 2, characterized by the above.

5. The addition amount of the inorganic filler is 1 to 70 wt%, and the particle size of the inorganic filler is 0.3 to 0.8 μm. The coating slurry according to Claim 1 or 2, characterized by the above.

6. The inorganic filler is Al ２ O ３ , SiO ２ , TiO ２ , ZrO ２ , one or more selected from MgO, CaO, AlOOH, SiC The coating slurry according to Claim 5, characterized by the above.

7. The solid content of the coating slurry is 7 to 20 wt%. The coating slurry according to Claim 1, characterized by the above.

8. The solvent is an NMP solvent. The coating slurry according to Claim 1, characterized by the above.

9. A separator comprising the coating slurry and the substrate according to any one of claims 1 to 8, wherein the coating slurry is applied to at least one surface of the substrate, and an irradiation treatment with ultraviolet rays having set energy and wavelength is performed to obtain the separator crosslinked by ultraviolet rays. A separator, characterized in that.

10. The thickness of the substrate is 5 to 20 μm. A separator according to claim 9, characterized in that.

11. The substrate is a PE separator. A separator according to claim 10, characterized in that.

12. A separator comprising a substrate and a coating located on at least one surface of the substrate, wherein the coating is applied with the coating slurry according to any one of claims 1 to 8, the film breaking temperature of the separator is greater than 180 ° C, its breakdown voltage is greater than 2.1 KV, and the breakdown voltage per unit thickness is greater than 5.1 KV / mil. A separator, characterized in that.

13. The film breaking temperature of the separator in the MD direction is greater than 210 ° C, and its film breaking temperature in the TD direction is greater than 190 ° C. A separator according to claim 12, characterized in that.

14. (1) Add 60 wt% or less of a super heat-resistant polymer resin adhesive and 1 to 20 wt% of an auxiliary adhesive to a solvent, dissolve thoroughly, then add 1 to 70 wt% of an inorganic filler and disperse uniformly to obtain a preliminary mixed slurry. Add a crosslinking agent to the solvent and dissolve completely to obtain a crosslinking agent solution. Add the crosslinking agent solution to the preliminary mixed slurry in a crosslinking amount of 0.001 to 6 wt% to obtain a slurry, a slurry preparation step; (2) A coating step of applying the prepared slurry to at least one surface of the substrate; (3) A phase transition step of immersing the separator obtained after coating in a coagulation tank containing a mixture of a first solvent and a non-solvent to perform a phase transition; (4) A drying step of washing and drying the product obtained in the above step (3) to obtain a composite separator after drying; (5) An ultraviolet crosslinking step of subjecting the composite separator to a crosslinking reaction by irradiation with ultraviolet rays to obtain an ultraviolet crosslinked composite separator, including. A method for manufacturing a separator according to any one of claims 9 to 13, characterized in that.

15. The wavelength of the ultraviolet light used is in the range of 210 nm to 420 nm, the ultraviolet cross-linking time is from 0.001 s to 10 s, and the irradiation light intensity is 50 mj / cm ２ or more. A method for manufacturing a separator according to claim 14, characterized in that.

16. The proportion of the first solvent in the sum of the masses of the first solvent and the non-solvent is 20 to 30 wt%. The method for manufacturing a separator according to claim 14, characterized by the above.

17. A battery comprising a separator, a positive electrode, a negative electrode, and an electrolyte, wherein the separator is the separator according to any one of claims 9 to 13. A battery, characterized by the above.

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