Battery diaphragm preparation method, battery diaphragm and battery

Abstract

The invention provides a battery diaphragm preparation method, a battery diaphragm and a battery. The method comprises the following steps: providing a diaphragm substrate; providing a ceramic layer coating dispersion liquid; coating the surface of the isolating membrane base material with the ceramic layer coating dispersion liquid, and forming a ceramic layer on the surface of the isolating membrane base material; and performing radiation treatment on the ceramic layer by adopting a radiation source to obtain the ceramic coating diaphragm. A radiation polymerization mode is adopted, high-energy particle rays are radiated to a coated ceramic layer, an organic polymer is induced to generate free radicals, and a polymer adhesive obtained after cross-linking polymerization forms a larger and higher-molecular-weight polymer network. As the adhesive is higher in strength and smaller in swelling degree, the adhesive force of the ceramic layer to the isolating membrane base material is increased, and the electrolyte absorption is smaller, so that the effects of improving the cell interface and prolonging the cycle life are achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of battery manufacturing, and in particular to a method for preparing a battery separator, a battery separator and a battery. Background Art

[0002] Lithium-ion batteries are widely used due to their high energy density, long cycle life, and environmental friendliness. With the continuous advancement of industrialization, the requirements for battery life and safety are becoming more and more stringent.

[0003] As one of the four main materials of lithium-ion batteries, the diaphragm isolates the positive and negative electrodes from contact and conducts lithium ions. However, with the pursuit of energy density and single battery capacity throughout the industry, the battery cells in the battery industry have gradually transitioned from low capacity and low energy density to high capacity and high energy density. Due to the pursuit of energy density, the anode pole piece needs to be compacted to the extreme, which directly leads to greater expansion of the anode during the cycle, and then leads to poor adhesion between the diaphragm and the pole piece, resulting in more interface problems; at the same time, the ceramic particles in the diaphragm coating are bonded with a polyacrylate adhesive with a low degree of polymerization and attached to the base film. Due to the low degree of polymerization of this adhesive, it will excessively absorb electrolyte in a highly polar electrolyte system, consume the relatively limited electrolyte in the system, and worsen the cycle.

[0004] The existing diaphragm has an adhesive layer coated on the surface of the ceramic layer for bonding with the pole piece. The bonding strength between the pole piece and the ceramic layer is much greater than the bonding between the substrate and the ceramic layer. In a system with extremely deteriorated bonding strength, the ceramic layer will peel off from the surface of the base film together with the adhesive layer, resulting in an uneven interface between the cathode and cathode, thereby causing interface problems caused by poor bonding. The existing method of strengthening the bonding between the ceramic layer and the base film is mostly to increase the content of adhesive in the ceramic layer, but the increase of adhesive will deteriorate other properties.

[0005] Ceramic adhesives with a lower degree of polymerization will experience greater electrolyte absorption and expansion in electrolytes with greater polarity. This absorption and expansion of the electrolyte greatly affects the cycle life of the battery and the adhesion between the ceramic layer and the base film.

[0006] To this end, in the production process of the diaphragm, it is necessary to improve the adhesion between the substrate and the ceramic layer of the diaphragm, and the diaphragm's excessive absorption of the electrolyte to improve the performance of the battery. Summary of the invention

[0007] Based on this, it is necessary to provide a battery separator preparation method, a battery separator and a battery to address the above technical problems.

[0008] A method for preparing a battery separator, comprising:

[0009] Providing a release film substrate;

[0010] Providing a ceramic layer coating dispersion;

[0011] Applying the ceramic layer coating dispersion on the surface of the isolation film substrate to form a ceramic layer on the surface of the isolation film substrate;

[0012] The ceramic layer is irradiated by using a radiation source to obtain a ceramic coated diaphragm.

[0013] In one embodiment, the radiation source is an ionizing radiation source or a non-ionizing radiation source. The ionizing radiation source includes: gamma rays, electron beams, and X-rays; the non-ionizing radiation source includes: ultraviolet rays.

[0014] In one embodiment, in the step of using a radiation source to irradiate the ceramic layer to obtain a ceramic coated diaphragm, the irradiation dose of the radiation treatment is greater than or equal to 50 Gy and less than 150 Gy.

[0015] In one of the embodiments, in the step of using a radiation source to perform radiation treatment on the ceramic layer to obtain a ceramic coated diaphragm, the temperature of the ceramic layer during the radiation treatment is 40° C. to 50° C.

[0016] In one embodiment, in the step of using a radiation source to radiate the ceramic layer to obtain a ceramic coated diaphragm, the radiation treatment time is greater than or equal to 3 minutes and less than or equal to 12 minutes.

[0017] In one embodiment, in the step of using a radiation source to radiate the ceramic layer to obtain a ceramic coated diaphragm, the energy of the radiation source is 60 keV and the irradiation intensity is 10 mV.

[0018] In one embodiment, the step of providing a ceramic layer coating dispersion comprises:

[0019] Provide ceramic powders, thickeners, adhesives and wetting agents;

[0020] The ceramic powder, thickener, binder and wetting agent are mixed with deionized water in a ratio of 94%:0.8%:5%:0.2% to obtain a dispersion with a solid content of 30%;

[0021] Wherein, the ceramic powder includes at least one of SiO2, Al2O3, CaO, TiO2, MgO, ZnO, SnO2, ZrO2, AlOOH, Mg(OH)2, and BaSO4;

[0022] The adhesive includes a homopolymer or copolymer of at least one of polyurethane, polyethylene terephthalate, polymethyl methacrylate, and polyacrylate.

[0023] In one embodiment, the step of irradiating the ceramic layer with a radiation light source to obtain a ceramic coated diaphragm comprises:

[0024] Using a radiation light source to perform radiation treatment on the ceramic layer;

[0025] PMMA is coated on the surface of the ceramic layer to obtain the ceramic coated diaphragm.

[0026] A battery separator is produced by the battery separator preparation method described in any of the above embodiments.

[0027] A battery comprises the battery separator described in the above embodiment.

[0028] The battery separator preparation method, battery separator and battery adopt radiation polymerization to irradiate high-energy particle rays on the coated ceramic layer to induce free radicals in the organic polymer, and the cross-linked polymerized polymer adhesive forms a larger and higher molecular weight polymer network. Since the adhesive strength is greater and the swelling degree is smaller, the adhesion of the ceramic layer to the separator substrate becomes greater and the electrolyte absorption is smaller, thereby achieving the effect of improving the battery cell interface and increasing the cycle life. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 A schematic diagram of a process for preparing a battery separator in one embodiment;

[0030] Figure 2 This is a diagram of the cell interface of a cell using the separator in the embodiment after cycling;

[0031] Figure 3 This is a diagram of the cell interface of a cell using the separator in the comparative example after cycling;

[0032] Figure 4 It is a capacity curve diagram of an embodiment and a comparative example in a cycle test in one embodiment. DETAILED DESCRIPTION

[0033] In order to make the purpose, technical solution and advantages of the present application more clearly understood, the present application is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0034] In one embodiment, Figure 1 As shown, a method for preparing a battery separator is provided, which comprises:

[0035] Step 110, providing an isolation film substrate.

[0036] In this embodiment, the isolation film substrate can support the ceramic layer. The material of the isolation film substrate can be PE (Polyethylene), PP (Polypropylene), or the isolation film substrate is a PE / PP / PE composite isolation film. The melting point of the isolation film substrate is 130-160°C, the thickness is 3-20um, the porosity is 20-50%, and the air permeability is 30-400sec / 100cc. The isolation film substrate can also be called a base film.

[0037] Step 120 , providing a ceramic layer coating dispersion.

[0038] In this embodiment, the ceramic layer coating dispersion liquid contains ceramic powder, a thickener, an adhesive and a wetting agent. The ceramic layer coating dispersion liquid is formed by mixing the ceramic powder, the thickener, the adhesive and the wetting agent.

[0039] Step 130 : coating the ceramic layer coating dispersion on the surface of the isolation film substrate to form a ceramic layer on the surface of the isolation film substrate.

[0040] In this embodiment, the ceramic layer coating dispersion is coated onto the surface of the isolation film substrate by gravure printing, with a coating thickness of 2 um. After drying, a ceramic layer is formed on the surface of the isolation film substrate.

[0041] Step 140: Use a radiation source to perform radiation treatment on the ceramic layer to obtain a ceramic coated diaphragm.

[0042] In this embodiment, the ceramic layer is irradiated by high-energy particle rays generated by the radiation source, inducing the organic polymer in the ceramic layer to generate free radicals, and the cross-linked polymer adhesive forms a larger, higher molecular weight polymer network, thereby effectively improving the bonding strength of the adhesive, and effectively improving the bonding strength between the ceramic layer and the isolation film substrate. The ceramic layer with increased polymerization degree can effectively reduce the absorption of electrolyte, thereby avoiding expansion caused by absorption of electrolyte, and also avoiding damage to the bonding between the ceramic layer and the base film due to expansion.

[0043] In this embodiment, without adding new components to the ceramic layer, a strong cross-linking network is formed between the molecules with a lower degree of polymerization and the small molecules, and between the small molecules and the macromolecules in the adhesive in the ceramic layer by means of radiation cross-linking polymerization, thereby greatly shortening the introduction process of new technologies (without adding active initiators) while achieving the goal of improving the battery cell interface and cycle life. It does not require the use of a catalyst and can be operated at room temperature, and has the characteristics of fast reaction, good consistency, and environmental friendliness.

[0044] In one embodiment, the radiation source is an ionizing radiation source or a non-ionizing radiation source. The ionizing radiation source includes: gamma rays, electron beams, and X-rays; the non-ionizing radiation source includes: ultraviolet rays.

[0045] In one embodiment, in the step of using a radiation source to perform radiation treatment on the ceramic layer to obtain a ceramic coated diaphragm, the radiation dose of the radiation treatment is greater than or equal to 50 Gy and less than 150 Gy.

[0046] It should be understood that when the irradiation dose is less than 150Gy, the puncture strength of the diaphragm increases with the increase of the irradiation dose, which indicates that after the ceramic layer is irradiated by high-energy particle rays, the cross-linking strength is improved to a certain extent, and at the same time, the overall strength of the diaphragm is also strengthened. At an irradiation dose of 150Gy, the puncture strength of the diaphragm begins to drop sharply, indicating that excessive irradiation will cause the original chemical bonds of the ceramic layer and the base membrane to break, resulting in strength deterioration. When the irradiation dose is greater than 150Gy, the puncture strength of the diaphragm continues to decrease with the increase of the irradiation dose. Therefore, in this embodiment, the irradiation dose is greater than or equal to 50Gy and less than 150Gy, which can effectively improve the puncture strength of the diaphragm.

[0047] In one embodiment, in the step of using a radiation source to perform radiation treatment on the ceramic layer to obtain a ceramic coated diaphragm, the temperature of the ceramic layer during the radiation treatment is 40° C. to 50° C.

[0048] In this embodiment, the temperature of the ceramic layer and the isolation film substrate during the radiation treatment process is 40°C to 50°C. It is worth mentioning that when the temperature of the ceramic layer and the isolation film substrate is 25°C, the peel strength increases with time, indicating that at this time when the temperature is low, the temperature has a greater impact on the overall cross-linking activity, and it is necessary to increase the time to enhance the cross-linking effect. When the temperature of the ceramic layer and the isolation film substrate is 40°C to 50°C, as time goes by, the cross-linking strength first increases and then decreases, and the maximum value of the peeling force reached by the ceramic layer at this temperature for 5 minutes of continuous radiation is greater than the peeling force reached by continuous radiation at 25°C for 10 minutes; and, when the ceramic layer is continuously irradiated at this temperature for 10 minutes, the peeling force decreases. This is because after the complete cross-linking reaction, continuous over-irradiation will cause the cross-linked molecules to break, resulting in deterioration (decline) of the peeling force. When the temperature of the ceramic layer and the isolation film substrate is 65°C, the peeling force gradually decreases with the increase of time, and at this temperature, the peeling force achieved by continuous radiation for 1 minute is smaller than the peeling force achieved by radiation for 5 minutes at 40°C to 50°C, indicating that under this condition, crosslinking is not complete. As time continues to increase, the peeling strength will continue to deteriorate. The reason is that after the complete reaction, continuous over-irradiation will cause the crosslinked molecules to break. In summary, when the temperature of the ceramic layer and the isolation film substrate is 40°C to 50°C, it is the best temperature range for radiation treatment (based on an irradiation dose of 100Gy, an energy of 60keV, and an irradiation intensity of 10mV).

[0049] In one embodiment, during the radiation treatment, the temperature of the ceramic layer is 45°C. In this embodiment, when the temperature of the ceramic layer and the isolation film substrate is 45°C, the crosslinking strength increases first and then decreases with time, and the ceramic layer reaches the maximum peeling force at this temperature after continuous radiation for 5 minutes. It can be seen that 45°C is the optimal temperature condition for radiation treatment (based on an irradiation dose of 100Gy, an energy of 60keV, and an irradiation intensity of 10mV).

[0050] In one embodiment, in the step of using a radiation source to perform radiation treatment on the ceramic layer to obtain a ceramic coated diaphragm, the radiation treatment time is greater than or equal to 3 minutes and less than or equal to 12 minutes.

[0051] It is worth mentioning that if the radiation treatment time is too short, the ceramic layer cannot be fully and completely cross-linked, and if the radiation time is too long, the molecules that have been completely cross-linked will be broken due to over-irradiation, which will lead to a decrease in bonding strength. Therefore, in this embodiment, the radiation treatment time is greater than or equal to 3 minutes and less than or equal to 12 minutes, which can make the ceramic layer fully and completely cross-linked and effectively avoid the breakage of the molecules after cross-linking.

[0052] In one embodiment, the radiation treatment time is 5 minutes. In this embodiment, when the temperature of the ceramic layer and the isolation film substrate is 45°C, the crosslinking strength increases first and then decreases with the increase of time, and the ceramic layer is continuously irradiated for 5 minutes at this temperature to reach the maximum peeling force. It can be seen that 5 minutes is the best time condition for radiation treatment (based on an irradiation dose of 100Gy, an energy of 60keV, and an irradiation intensity of 10mV).

[0053] In one embodiment, in the step of using a radiation source to radiate the ceramic layer to obtain a ceramic coated diaphragm, the energy of the radiation source is 60 keV and the irradiation intensity is 10 mV.

[0054] In this embodiment, the energy of the radiation source is 60keV, the irradiation intensity is 10mV, and the radiation is carried out for 5 minutes at a temperature of 45°C, which can fully cross-link and polymerize the organic polymer of the ceramic layer, maximize the peeling force between the ceramic layer and the isolation film substrate, and maximize the puncture strength of the separator.

[0055] In one embodiment, the step of providing a ceramic layer coating dispersion comprises:

[0056] Provide ceramic powders, thickeners, adhesives and wetting agents;

[0057] The ceramic powder, thickener, binder and wetting agent are mixed with deionized water in a ratio of 94%:0.8%:5%:0.2% to obtain a dispersion with a solid content of 30%;

[0058] Wherein, the ceramic powder includes at least one of SiO2, Al2O3, CaO, TiO2, MgO, ZnO, SnO2, ZrO2, AlOOH, Mg(OH)2, and BaSO4;

[0059] The adhesive includes a homopolymer or copolymer of at least one of polyurethane, polyethylene terephthalate, polymethyl methacrylate, and polyacrylate.

[0060] In this embodiment, the ceramic powder can also be called ceramic particles. The ceramic powder can be mixed with at least one of the above-mentioned SiO2, Al2O3, CaO, TiO2, MgO, ZnO, SnO2, ZrO2, AlOOH, Mg(OH)2, and BaSO4. The adhesive is a homopolymer or copolymer of at least one organic polymer selected from the group consisting of polyurethane, polyethylene terephthalate, polymethyl methacrylate, and polyacrylate. The ceramic powder, thickener, adhesive, and wetting agent are mixed with deionized water in a ratio of 94%:0.8%:5%:0.2% to obtain a dispersion with a solid content of 30%. After the dispersion is coated on the surface of the isolation membrane substrate, it is dried and cured to form a ceramic layer. Since the ceramic layer contains organic polymers, its molecules can be cross-linked under the radiation of the radiation source, thereby effectively improving the overall strength and adhesion of the ceramic layer.

[0061] In one embodiment, the step of using a radiation light source to radiate the ceramic layer to obtain a ceramic coated diaphragm comprises:

[0062] Using a radiation light source to perform radiation treatment on the ceramic layer;

[0063] PMMA (Polymethyl Methacrylate) is coated on the surface of the ceramic layer to obtain the ceramic coated diaphragm.

[0064] In this embodiment, after the ceramic layer is subjected to radiation treatment, PMMA is coated on the surface of the ceramic layer to encapsulate the ceramic layer.

[0065] Performance parameter comparison:

[0066] This section uses the lithium-ion battery separators and lithium batteries prepared in Examples 1-3 and Comparative Example 1 to test the shrinkage rate of the separators, the peel force between the ceramic layer and the base film, the puncture strength, the battery capacity in the cycle test and other properties. The preparation conditions such as the raw material components and radiation conditions in each example and comparative example are shown below, and the test results are shown in Tables 1 to 3.

[0067] Example 1: Alumina, thickener, polyacrylate, and wetting agent are mixed with deionized water in a ratio of 94%:0.8%:5%:0.2% to obtain a dispersion with a solid content of 30%. The dispersion is coated on the surface of a 7um HDPE base film by gravure, and the ceramic layer thickness is 2um. After drying, a ceramic coated diaphragm is obtained. At this time, the diaphragm is passed through a device with high-energy xRay for rapid crosslinking, with an irradiation dose of 50Gy, an energy of 60keV, an irradiation intensity of 10mV, an irradiation time of 5min, and a temperature of 45°C. After crosslinking, PMMA is coated on the ceramic surface. Recorded as Example diaphragm 1;

[0068] Example 2: Alumina, thickener, polyacrylate, wetting agent in a ratio of 94%: 0.8%: 5%: 0.2%, mixed with deionized water to obtain a dispersion with a solid content of 30%, and the dispersion was coated on the surface of 7um HDPE base film by gravure, the ceramic layer thickness was 2um, and the ceramic coated diaphragm was obtained after drying. At this time, the diaphragm was passed through a device with high-energy X-Ray for rapid crosslinking, with an irradiation dose of 100Gy, an energy of 60keV, an irradiation intensity of 10mV, an irradiation time of 5min, and a temperature of 45°C. After crosslinking, PMMA was coated on the ceramic surface.

[0069] It is recorded as Example 2.

[0070] Example 3: Alumina, thickener, polyacrylate, wetting agent in a ratio of 94%: 0.8%: 5%: 0.2%, mixed with deionized water to obtain a dispersion with a solid content of 30%, and the dispersion was coated on the surface of 7um HDPE base film by gravure, the ceramic layer thickness was 2um, and the ceramic coated diaphragm was obtained after drying. At this time, the diaphragm was passed through a device with high-energy xRay for rapid crosslinking, with an irradiation dose of 150Gy, an energy of 60keV, an irradiation intensity of 10mV, an irradiation time of 5min, and a temperature of 45°C. After crosslinking, PMMA was coated on the ceramic surface.

[0071] It is recorded as Example diaphragm 3;

[0072] Comparative example: Alumina, thickener, polyacrylate, and wetting agent are mixed with deionized water in a ratio of 94%:0.8%:5%:0.2% to obtain a dispersion with a solid content of 30%. The dispersion is coated on the surface of a 7um HDPE base film by gravure printing, and the ceramic layer has a thickness of 2um. After drying, a ceramic coated diaphragm is obtained, and then PMMA is coated on the ceramic surface.

[0073] Subsequently, a battery was manufactured, with LiFeO4 used as the positive electrode and graphite used as the negative electrode, and the batteries were wound into 5Ah soft-pack batteries. The battery using the separator of the embodiment is the battery of the embodiment, and the battery using the separator of the comparative example is the battery of the comparative example.

[0074] Table 1 Diaphragm thermal shrinkage data

[0075]

[0076]

[0077] Table 2 Separator peeling force (ceramic layer and base film)

[0078] type Peel force N / m Example 15.0 Comparative Example 9.4

[0079] Table 3 Puncture strength

[0080] type Puncture strength / kgf Example 1 479 Example 2 500 Example 3 400 Comparative Example 440

[0081] Combined with Table 2 to Table 4, Figure 2 and Figure 3 The shrinkage rates of the diaphragms of Examples 1, 2 and 3 are significantly smaller than that of the comparative example, and the peeling forces are also significantly greater than those of the comparative example. The puncture strengths of Examples 1 and 2 are significantly greater than those of the comparative example.

[0082] By comparing Example 1, Example 2, Example 3 and the comparative example, it can be seen that the improvement in thermal shrinkage of the diaphragm is due to the increase in the molecular weight of the internal adhesive, which increases the overall thermal stability, thereby improving the high-temperature thermal shrinkage. And as the irradiation dose increases, its thermal shrinkage ability improves more significantly. The bonding force between the ceramic layer and the base film of the example diaphragm is greater than that of the comparative example, indicating that after cross-linking, the strength of the adhesive increases, and the pore binding force with the base film surface increases.

[0083] Puncture strength: When the irradiation dose is less than 150 Gy, the puncture strength of the diaphragm increases with the increase of the irradiation dose, indicating that after irradiation, while increasing the cross-linking strength of the ceramic coating to a certain extent, the overall strength of the diaphragm also becomes stronger. When the irradiation dose is 150 Gy, the strength drops sharply, indicating that excessive irradiation will cause the original chemical bonds of the ceramic layer and the base film to break, resulting in strength deterioration, such as: as shown in Example 3.

[0084] Using Example 2 as the Base solution for battery cell evaluation, the battery cell performance was evaluated. Figure 2 and Figure 3 As shown, the results show that the interface of the battery cell using the separator of Example 2 has good interface consistency after cycling and no obvious abnormalities; purple spots of lithium precipitation appear on the interface of the comparative example, indicating that the membrane has better adhesion after cross-linking and improved interface consistency.

[0085] Combination Figure 4 After 1000 cycles, the capacity retention rate of Example 2 is 91%, while that of the comparative example is only 79%, indicating that the poor interface of the uncross-linked diaphragm leads to loss of active materials and consumption of electrolyte by small molecular weight adhesives in the diaphragm, resulting in a large difference in cycle retention rate.

[0086] As shown in Table 4, the effects of different parameters on the performance of the diaphragm are summarized. The experiment fixed the irradiation dose at 100Gy, the energy at 60keV, and the irradiation intensity at 10mV. The irradiation time and temperature were changed to explore the effects of these two variables on the final diaphragm. The experimental results show that at a temperature of 25°C, the peel strength increases with time, indicating that at this time when the temperature is low, it will affect the overall cross-linking activity and increase the time required for cross-linking. At a temperature of 45°C, with the increase of time, the cross-linking strength first increases and then decreases, and the maximum value of the peel force is greater than that at 25°C and 10min (variable 3), and decreases at 45°C and 10min. This is attributed to the fact that after the complete reaction, continuous over-irradiation will cause the cross-linked molecules to break, resulting in deterioration of the peel force. When the temperature is 65℃, the peel strength decreases with the increase of time, and the peel strength value corresponding to 65℃, 1min (variable 7) is smaller than the peel strength value corresponding to 45℃, 5min (variable 5), indicating that the crosslinking is not complete under this condition. The deterioration of the peel strength after the time continues to increase is attributed to the continuous over-irradiation after the complete reaction, which will cause the crosslinked molecules to break. In summary, 45℃, 5min is the best temperature and time condition (based on the irradiation dose of 100Gy, energy of 60key, and irradiation intensity of 10mV)

[0087] Table 4 Effect of different parameters on diaphragm performance

[0088] type Time / min Temperature ℃ Peel force N / m Variable 1 1 25 12.5 Variable 2 5 25 16.3 Variable 3 10 25 22.0 Variable 4 1 45 21.2 Variable 5 5 45 30.0 Variable 6 10 45 25.1 Variable 7 1 65 27.2 Variable 8 5 65 19.0 Variable 9 10 65 6.1

[0089] In one embodiment, a battery separator is provided. The battery separator is produced by the battery separator preparation method described in any one of the above embodiments.

[0090] In this embodiment, the battery separator includes a separator substrate and a ceramic layer, wherein the ceramic layer is obtained by mixing ceramic powder, thickener, adhesive and wetting agent in a ratio of 94%:0.8%:5%:0.2% with deionized water to obtain a dispersion with a solid content of 30%, which is then coated on the separator substrate and dried and solidified. The ceramic layer is irradiated with high-energy particle rays emitted by a radiation light source, wherein:

[0091] In one embodiment, a battery is provided, comprising the battery separator described in the above embodiment.

[0092] The technical features of the above embodiments may be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0093] The above-mentioned embodiments only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the patent of the present application shall be subject to the attached claims.

Claims

1. A method for preparing a battery separator, characterized in that: include: Providing a release film substrate; Providing a ceramic layer coating dispersion; Applying the ceramic layer coating dispersion on the surface of the isolation film substrate to form a ceramic layer on the surface of the isolation film substrate; The ceramic layer is irradiated by using a radiation source to obtain a ceramic coated diaphragm.

2. The method according to claim 1, characterized in that The radiation source is an ionizing radiation source or a non-ionizing radiation source. The ionizing radiation source includes gamma rays, electron beams, and X-rays; the non-ionizing radiation source includes ultraviolet rays.

3. The method according to claim 1, characterized in that: In the step of using a radiation source to irradiate the ceramic layer to obtain a ceramic coated diaphragm, the irradiation dose of the radiation treatment is greater than or equal to 50 Gy and less than 150 Gy.

4. The method according to claim 1, characterized in that: In the step of using a radiation source to perform radiation treatment on the ceramic layer to obtain a ceramic coated diaphragm, during the radiation treatment, the temperature of the ceramic layer is 40° C. to 50° C.

5. The method according to claim 1, characterized in that In the step of using a radiation source to perform radiation treatment on the ceramic layer to obtain a ceramic coated diaphragm, the radiation treatment time is greater than or equal to 3 minutes and less than or equal to 12 minutes.

6. The method according to claim 1, characterized in that In the step of using a radiation source to radiate the ceramic layer to obtain a ceramic coated diaphragm, the energy of the radiation source is 60 keV and the irradiation intensity is 10 mV.

7. The method according to claim 1, characterized in that The step of providing a ceramic layer coating dispersion comprises: Provide ceramic powders, thickeners, adhesives and wetting agents; The ceramic powder, thickener, binder and wetting agent are mixed with deionized water in a ratio of 94%:0.8%:5%:0.2% to obtain a dispersion with a solid content of 30%; Wherein, the ceramic powder includes at least one of SiO2, Al2O3, CaO, TiO2, MgO, ZnO, SnO2, ZrO2, AlOOH, Mg(OH)2, and BaSO4; The adhesive includes a homopolymer or copolymer of at least one of polyurethane, polyethylene terephthalate, polymethyl methacrylate, and polyacrylate.

8. The method according to claim 1, characterized in that The step of using a radiation light source to radiate the ceramic layer to obtain a ceramic coated diaphragm comprises: Using a radiation light source to perform radiation treatment on the ceramic layer; PMMA is coated on the surface of the ceramic layer to obtain the ceramic coated diaphragm.

9. A battery separator, characterized in that: The battery separator is produced by the method for preparing the battery separator described in any one of claims 1 to 8.

10. A battery, characterized in that: The battery separator according to claim 9 is included.

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