A lithium ion battery separator with low transverse crimping rate and a preparation method thereof

Abstract

The application belongs to the technical field of lithium ion batteries, and specifically discloses a preparation method of a lithium ion battery diaphragm with low transverse curling rate, which comprises the following steps: S1: preparing a binder; S2: preparing a composite slurry; and S3: preparing a lithium ion battery diaphragm. The application provides a lithium ion battery diaphragm with low transverse curling rate. Through optimization of the components of the diaphragm coating on both sides of the battery diaphragm and optimization of the coating process of the diaphragm coating on the diaphragm body, the adhesion between the diaphragm coating and the diaphragm body of the prepared lithium ion battery diaphragm is strong, the transverse curling rate of the battery diaphragm is reduced, and thus the overall performance of the battery diaphragm is optimized.

Description

Technical Field

[0001] The present invention belongs to the technical field of lithium-ion batteries, and in particular relates to a lithium-ion battery separator with a low transverse curling rate and a preparation method thereof. Background Art

[0002] As a rechargeable battery, lithium-ion batteries rely on the movement of lithium ions between the positive and negative electrodes to work. During the charging and discharging process, Li + Insertion and deinsertion back and forth between the two electrodes: During charging, Li + It is deintercalated from the positive electrode and intercalated into the negative electrode through the electrolyte, and the negative electrode is in a lithium-rich state; the opposite is true during discharge.

[0003] Lithium-ion battery separators play a vital role in batteries. They not only prevent direct contact between the positive and negative electrodes that causes short circuits, but also allow lithium ions to pass freely between the positive and negative electrodes to form a charge and discharge circuit.

[0004] However, during the production and use of diaphragms, lateral curling of the diaphragm is a common problem. Lateral curling mainly occurs at the edge of the diaphragm. The main causes of lateral curling of the diaphragm are: unevenness of the diaphragm material, defects in the production process, or improper operation during battery assembly. Lateral curling of the diaphragm will make the internal structure of the battery uneven, affect the migration of lithium ions, increase the internal resistance of the battery, and thus reduce the battery's charge and discharge efficiency and cycle stability. In addition, the lateral curling problem of the diaphragm will also cause uneven distribution of electrolyte on the diaphragm surface, resulting in excessive or insufficient electrolyte in local areas inside the battery, affecting the consistency and safety of the battery. Summary of the Invention

[0005] The purpose of the present invention is to overcome the above problems existing in the prior art and provide a lithium-ion battery separator with a low transverse curling rate. By optimizing the components of the separator coating on both sides of the battery separator and optimizing the coating process of the separator coating on the separator body, the adhesion between the separator coating and the separator body of the prepared lithium-ion battery separator is strong, and the transverse curling rate of the battery separator is reduced, thereby optimizing the overall performance of the battery separator.

[0006] In order to achieve the above technical objectives and the above technical effects, the present invention is implemented through the following technical solutions:

[0007] An embodiment of the first aspect of the present invention provides a method for preparing a lithium-ion battery separator with a low transverse curling rate, the method comprising the following steps:

[0008] S1: Preparation of binder

[0009] Weighing PVA powder into a mixer, adding a crosslinking agent to the mixer, and mixing uniformly to prepare a mixture, adjusting the pH of the mixture to 3-5 with citric acid to prepare a binder, and adding the binder to water at 60-100° C. and allowing it to fully react to prepare a binder;

[0010] S2: Preparation of composite slurry

[0011] Weighing ceramic particles into a second mixer, adding a dispersant to the second mixer, and mixing uniformly to prepare a second mixture, adding the second mixture into water to prepare a pre-slurry, adding the binder prepared in step S1 into the pre-slurry, and mixing and stirring to prepare a composite slurry;

[0012] S3: Preparation of lithium-ion battery separators

[0013] The composite slurry is coated on both sides of the diaphragm body using a roller coater, and the diaphragm body coated with the composite slurry is dried to form a diaphragm coating on both sides of the diaphragm body to prepare a lithium ion battery diaphragm.

[0014] Further, in step S1, in step S1, the cross-linking agent is methyl acetoacetate;

[0015] The mass ratio of PVA powder to cross-linking agent is 1:(0.10-0.30);

[0016] The mass ratio of binder to water is 1:(8-10).

[0017] Furthermore, in step S1 and step S2, the water is deionized water.

[0018] Furthermore, in step S2, the D50 of the ceramic particles is not greater than 1.2 μm.

[0019] Furthermore, in step S2, the dispersant is any one or more of polyacrylic acid sodium salt and polytetrafluoroethylene mixed in any proportion;

[0020] The mass ratio of the ceramic particles to the dispersant is (100-140):1.

[0021] Furthermore, in step S2, the mass ratio of the second mixture to water is (0.6-1.0):1;

[0022] The mass ratio of the binder to the pre-slurry is 1:(3-5).

[0023] Furthermore, in step S2, during the mixing and stirring process, the mixing and stirring rate is 30-40 rpm / min, and the mixing and stirring time is 30-50 min.

[0024] Further, in step S3, the coating speed of the roll coater is 100-130 m / min.

[0025] In step S3, the coating pressure is 0.5-0.6 MPa, and the coating gap is 3-5 μm.

[0026] Further, in step S3, during the drying process, the drying temperature is 60-70℃, and the drying time is 10-20 min.

[0027] The embodiment of the second aspect of the application provides a lithium ion battery separator with low transverse edge curling rate, which is prepared by the preparation method of the lithium ion battery separator with low transverse edge curling rate provided by the embodiment of the first aspect of the application.

[0028] Compared with the prior art, the application has the following beneficial effects:

[0029] 1. The lithium ion battery separator with low transverse edge curling rate effectively reduces the transverse edge curling rate, improves the overall performance and reliability of the lithium ion battery when used in the lithium ion battery, and thus promotes the further development of lithium ion battery technology.

[0030] 2. The lithium ion battery separator with low transverse edge curling rate has strong adhesion between the separator coating on both sides of the battery separator and the separator body, and the transverse edge curling rate of the battery separator is reduced, thereby optimizing the overall performance of the battery separator.

[0031] 3. In the application, the separator coating is coated on both sides of the separator body by a composite slurry, and then prepared after drying treatment; the composite slurry is prepared by mixing a binder and a pre-slurry, the binder is prepared by mixing PVA powder and methyl acetoacetate and then putting it into water, and the pre-slurry is prepared by mixing ceramic particles and a dispersing agent and then mixing with water; the long molecular chain of PVA (polyvinyl alcohol) is tightly combined with the ceramic particles through physical entanglement, thereby enhancing the adhesion between the particles; meanwhile, the rich hydroxyl functional groups on the PVA molecular chain can react with the ceramic particles under the action of methyl acetoacetate as an initiator, thereby further improving the adhesion and uniformity of the separator coating; the uniformity of the separator coating is also significantly improved through the dual action of physical entanglement and chemical grafting, thereby effectively reducing the edge curling phenomenon that may occur due to the uneven surface tension of the separator body, and thus optimizing the overall performance of the separator body.

[0032] 4. In the present invention, by optimizing the coating process when the composite slurry is coated on both sides of the diaphragm body, that is, optimizing the parameters such as the coating speed, coating pressure and coating gap, it is ensured that the composite slurry is evenly coated on the surface of the diaphragm body to form a coating with uniform thickness and smooth surface, thereby avoiding the difference in diaphragm performance caused by uneven coating, thereby significantly improving the lateral curling problem of lithium-ion battery diaphragms and improving the quality and performance of battery diaphragms. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] The drawings described herein are used to provide a further understanding of the present invention and constitute a part of this application. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0034] Figure 1 Schematic diagram of cross-linking formation of the adhesive provided in Example 1 of the present invention;

[0035] Figure 2 This is a schematic diagram of the grafting of ceramic particles and a binder provided in Example 1 of the present invention. DETAILED DESCRIPTION

[0036] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts shall fall within the scope of protection of the present invention.

[0037] An embodiment of the first aspect of the present invention provides a method for preparing a lithium-ion battery separator with a low transverse curling rate, the method comprising the following steps:

[0038] S1: Preparation of binder

[0039] Weighing PVA powder into a mixer, adding a crosslinking agent to the mixer, and mixing uniformly to prepare a mixture, adjusting the pH of the mixture to 3-5 with citric acid to prepare a binder, and adding the binder to water at 60-100° C. and allowing it to fully react to prepare a binder;

[0040] Among them, in mixture 1, the cross-linking agent is methyl acetoacetate;

[0041] The mass ratio of PVA powder to cross-linking agent is 1:(0.10-0.30);

[0042] In the binder, the mass ratio of binder to water is 1:(8-10);

[0043] Among them, the cross-linking formation process of the binder is as follows Figure 1As shown, that is, the cross-linking reaction process of PVA powder and cross-linking agent methyl acetoacetate;

[0044] S2: Preparation of composite slurry

[0045] Weighing ceramic particles into a second mixer, adding a dispersant to the second mixer, and mixing uniformly to prepare a second mixture, adding the second mixture into water to prepare a pre-slurry, adding the binder prepared in step S1 into the pre-slurry, and mixing and stirring to prepare a composite slurry; during the mixing and stirring process, the mixing and stirring rate is 30-40 rpm / min, and the mixing and stirring time is 30-50 min;

[0046] The reaction formula of ceramic particles (ceramic materials with alumina (Al2O3) as the main component) and binder is as follows: Figure 2 As shown in the figure, this is the grafting reaction process between ceramic particles and binder. In this process, the physical entanglement of the long molecular chains of PVA powder can achieve close bonding with ceramic particles and enhance the adhesion between particles. In addition, the hydroxyl functional groups on the PVA molecular chains are used to graft with ceramic particles through methyl acetoacetate initiator to improve adhesion and uniformity.

[0047] Wherein, in step S1 and step S2, the water used is deionized water;

[0048] In step S2, the D50 of the ceramic particles is not greater than 1.2 μm;

[0049] In the second mixture, the dispersant is any one or more of sodium polyacrylate and polytetrafluoroethylene mixed in any proportion;

[0050] The mass ratio of ceramic particles to dispersant is (100-140):1;

[0051] In the pre-slurry, the mass ratio of the second mixture to water is (0.6-1.0):1;

[0052] In the composite slurry, the mass ratio of binder to pre-slurry is 1:(3-5);

[0053] S3: Preparation of lithium-ion battery separators

[0054] The composite slurry is coated on both sides of the diaphragm body using a roller coater, and the diaphragm body coated with the composite slurry is dried to form a diaphragm coating on both sides of the diaphragm body to prepare a lithium ion battery diaphragm;

[0055] In the process of coating the composite slurry on both sides of the diaphragm body, the coating rate is 120-160 m / min, the coating pressure is 0.5-0.6 MPa, and the coating gap is 3-5 μm.

[0056] PVA plays a dual role in enhancing the performance of lithium ion battery separators. Firstly, the physical entanglement of the long molecular chains of PVA powder can achieve close combination with ceramic particles, enhancing the adhesion between particles. Secondly, the hydroxyl functional groups on the PVA molecular chain can undergo grafting reaction with ceramic particles through methyl acetoacetate initiator, improving adhesion and uniformity.

[0057] Combining the dual action mechanisms of physical entanglement and chemical grafting, the uniformity of the prepared lithium ion battery separator is significantly improved, thereby effectively reducing the curling phenomenon caused by uneven tension of the separator, thereby improving the quality and safety of battery manufacturing.

[0058] Embodiments of the second aspect of the application provide a lithium ion battery separator with low lateral curling rate, which is prepared by the preparation method of the lithium ion battery separator with low lateral curling rate provided by embodiments of the first aspect of the application.

[0059] Specifically, the lithium ion battery separator includes a separator body and a separator coating coated on both sides of the separator body. The separator coating is formed by coating the composite slurry on both sides of the separator body and then drying.

[0060] The following are specific embodiments. In the following embodiments, unless otherwise specified, each raw material can be obtained commercially.

[0061] Embodiment 1

[0062] The present embodiment provides a preparation method of a lithium ion battery separator, which comprises the following steps:

[0063] S1: preparing a binder

[0064] PVA powder is weighed into a mixer one, methyl acetoacetate is added to the mixer one, and after mixing, a mixture one is prepared. Citric acid is used to adjust the pH value of the mixture one to 4 to prepare a binding material. The binding material is added to deionized water at 80℃, and after sufficient reaction, a binder is prepared.

[0065] In the mixture one, the mass ratio of PVA powder to methyl acetoacetate is 10:2.

[0066] In the binder, the mass ratio of the binding material to water is 1:9.

[0067] S2: preparing a composite slurry

[0068] Weigh ceramic particles into a second mixer, add sodium polyacrylate to the second mixer, and mix well to prepare a second mixture. Add the second mixture into deionized water to prepare a pre-slurry. Add the binder prepared in step S1 into the pre-slurry, mix and stir at 35 rpm for 40 minutes, and prepare a composite slurry after mixing and stirring.

[0069] Wherein, in step S2, the D50 of the ceramic particles is 1.2 μm;

[0070] In mixture 2, the mass ratio of ceramic particles to sodium polyacrylate is 120:1;

[0071] In the pre-slurry, the mass ratio of mixture 2 to water is 0.75:1;

[0072] In the composite slurry, the mass ratio of binder to pre-slurry is 1:4;

[0073] S3: Preparation of lithium-ion battery separators

[0074] The composite slurry is coated on both sides of the diaphragm body using a roller coater, and the diaphragm body coated with the composite slurry is dried to form a diaphragm coating on both sides of the diaphragm body to prepare a lithium ion battery diaphragm;

[0075] In the process of coating the composite slurry on both sides of the diaphragm body, the coating rate was 120 m / min, the coating pressure was 0.5 MPa, and the coating gap was 3 μm.

[0076] Example 2

[0077] This embodiment provides a method for preparing a lithium-ion battery separator, which comprises the following steps:

[0078] S1: Preparation of binder

[0079] Weighing PVA powder into a mixer, adding methyl acetoacetate to the mixer, and mixing uniformly to prepare a mixture, adjusting the pH of the mixture to 5 with citric acid to prepare a binder, and adding the binder to deionized water at 100° C., and allowing it to fully react to prepare a binder;

[0080] Among them, in the mixture 1, the mass ratio of PVA powder to methyl acetoacetate is 10:1;

[0081] In the binder, the mass ratio of binder to water is 1:10;

[0082] S2: Preparation of composite slurry

[0083] The ceramic particles are weighed into the second mixer, and sodium polyacrylate is added into the second mixer. After uniform mixing, the second mixture is prepared. The second mixture is poured into deionized water to prepare a pre-slurry. The binder prepared in step S1 is poured into the pre-slurry, and mixed and stirred at 30 rpm / min for 50 min. After mixing and stirring, the composite slurry is prepared.

[0084] In step S2, the D50 of the ceramic particles is 1.2 μm.

[0085] In the second mixture, the mass ratio of the ceramic particles to sodium polyacrylate is 100:1.

[0086] In the pre-slurry, the mass ratio of the second mixture to water is 0.6:1.

[0087] In the composite slurry, the mass ratio of the binder to the pre-slurry is 1:5.

[0088] S3: Preparation of a lithium ion battery separator

[0089] The composite slurry is coated on both sides of the separator body using a roll coater, and the separator body coated with the composite slurry is dried to form a separator coating on both sides of the separator body, thereby preparing a lithium ion battery separator.

[0090] In the process of coating the composite slurry on both sides of the separator body, the coating speed is 130 m / min, the coating pressure is 0.6 MPa, and the coating gap is 5 μm.

[0091] Example 3

[0092] The present embodiment provides a preparation method of a lithium ion battery separator, which comprises the following steps:

[0093] S1: Preparation of a binder

[0094] PVA powder is weighed into the first mixer, and methyl acetoacetate is added into the first mixer. After uniform mixing, the first mixture is prepared. The pH value of the first mixture is adjusted to 3 using citric acid to prepare a binding material. The binding material is poured into deionized water at 60°C, and fully reacted to prepare a binder.

[0095] In the first mixture, the mass ratio of the PVA powder to methyl acetoacetate is 10:3.

[0096] In the binder, the mass ratio of the binding material to water is 1:8.

[0097] S2: Preparation of a composite slurry

[0098] Weigh ceramic particles into a second mixer, add sodium polyacrylate to the second mixer, and mix well to prepare a second mixture. Add the second mixture into deionized water to prepare a pre-slurry. Add the binder prepared in step S1 into the pre-slurry, mix and stir at 40 rpm / min for 30 minutes, and prepare a composite slurry after mixing and stirring.

[0099] Wherein, in step S2, the D50 of the ceramic particles is 1.2 μm;

[0100] In mixture 2, the mass ratio of ceramic particles to sodium polyacrylate is 140:1;

[0101] In the pre-slurry, the mass ratio of mixture 2 to water is 1:1;

[0102] In the composite slurry, the mass ratio of binder to pre-slurry is 1:3;

[0103] S3: Preparation of lithium-ion battery separators

[0104] The composite slurry is coated on both sides of the diaphragm body using a roller coater, and the diaphragm body coated with the composite slurry is dried to form a diaphragm coating on both sides of the diaphragm body to prepare a lithium ion battery diaphragm;

[0105] In the process of coating the composite slurry on both sides of the diaphragm body, the coating rate was 160 m / min, the coating pressure was 0.55 MPa, and the coating gap was 4 μm.

[0106] Example 4

[0107] This embodiment provides a method for preparing a lithium-ion battery separator. Compared with Example 1, in this embodiment, the dispersant is polytetrafluoroethylene, and the remaining operating steps are the same as in Example 1.

[0108] Comparative Example 1

[0109] This comparative example provides a method for preparing a lithium-ion battery separator. Compared with Example 1, in this comparative example, the cross-linking agent is polyvinylidene fluoride, and the remaining operating steps are the same as those in Example 1.

[0110] Comparative Example 2

[0111] This comparative example provides a method for preparing a lithium-ion battery separator. Compared with Example 1, in this comparative example, the cross-linking agent is an aldehyde compound glutaraldehyde, and the remaining operating steps are the same as those in Example 1.

[0112] Comparative Example 3

[0113] This comparative example provides a method for preparing a lithium-ion battery separator. Compared with Example 1, in this comparative example, the mixing stirring rate is replaced from 35 rpm / min to 20 rpm / min, and the remaining operating steps are the same as those in Example 1.

[0114] Comparative Example 4

[0115] This comparative example provides a method for preparing a lithium-ion battery separator. Compared with Example 1, in this comparative example, the coating rate is replaced from 120 m / min to 60 m / min, and the remaining operating steps are the same as those in Example 1.

[0116] Experimental example

[0117] The thickness deviation and transverse curling rate of the lithium ion battery separators prepared in Examples 1-4 and Comparative Examples 1-4 were detected and calculated, and compared with ordinary ceramic coating separators. Then, the thickness deviation change rate (%) and transverse curling rate change rate (%) of the lithium ion battery separators prepared in Examples 1-4 and Comparative Examples 1-4 were calculated. The calculation formula is as follows:

[0118]

[0119] The calculation results are shown in Table 1;

[0120] Table 1

[0121] Group Thickness deviation change rate / % Transverse hemming rate change / % Example 1 28 43 Example 2 24 38 Example 3 24 34 Example 4 25 39 Comparative Example 1 21 30 Comparative Example 2 15 23 Comparative Example 3 18 23 Comparative Example 4 19 25

[0122] According to the data in Table 1, it can be seen that in the present application, the lithium ion battery separator prepared in Example 1 has a thickness deviation reduced by 28% and a transverse curling rate reduced by 43% compared with the ordinary ceramic coating separator. It can also be seen from the data in Table 1 that the data of Examples 1-4 are better than those of Comparative Examples 1-4, indicating that the lithium ion battery separator prepared in the present application can effectively reduce the curling phenomenon of the separator; specifically:

[0123] Comparative Example 1 uses polyvinylidene fluoride as a cross-linking agent. Although it has a certain effect in reducing the transverse curling, the cost of polyvinylidene fluoride is relatively high, and its effect on improving the transverse curling of the lithium-ion battery separator is far less than that of Example 1.

[0124] Comparative Example 2 uses an aldehyde compound as a cross-linking agent, which cannot provide sufficient thermal stability, resulting in an insufficient reduction in the transverse curling rate;

[0125] In Comparative Example 3, the stirring rate was reduced, resulting in uneven mixing of the slurry, affecting the coating quality, and further affecting the quality of the prepared lithium-ion battery separator;

[0126] In Comparative Example 4, the coating rate is reduced, which may easily lead to uneven coating during the coating process, thereby affecting the performance of the prepared lithium-ion battery separator.

[0127] The present invention provides a lithium-ion battery separator with a low transverse curling rate, which effectively reduces the transverse curling rate. When used in lithium-ion batteries, the separator can improve the overall performance and reliability of the lithium-ion battery, thereby promoting the further development of lithium-ion battery technology. The present invention also provides a preparation method of a lithium-ion battery separator with a low transverse curling rate. By optimizing the coating process when the composite slurry is coated on both sides of the separator body, that is, optimizing parameters such as the coating speed, coating pressure and coating gap, it is ensured that the composite slurry is evenly coated on the surface of the separator body to form a coating with uniform thickness and smooth surface, thereby avoiding differences in separator performance caused by uneven coating, thereby significantly improving the transverse curling problem of the lithium-ion battery separator and improving the quality and performance of the battery separator.

[0128] Throughout this specification, references to terms such as "one embodiment," "example," or "specific example" indicate that the specific features, structures, materials, or characteristics described in conjunction with that embodiment or example are included in at least one embodiment or example of the present invention. In this specification, schematic representations of these terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

[0129] The basic principles, main features, and advantages of the present invention are shown and described above. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The above embodiments and descriptions are merely illustrative of the principles of the present invention. Various changes and modifications may be made to the present invention without departing from the spirit and scope of the present invention, and such changes and modifications fall within the scope of the invention as claimed.

Claims

1. A method for preparing a lithium-ion battery separator with a low transverse curling rate, characterized in that: The preparation method comprises the following steps: S1: Preparation of binder Weighing PVA powder into a mixer, adding a crosslinking agent to the mixer, and mixing uniformly to prepare a mixture, adjusting the pH of the mixture to 3-5 with citric acid to prepare a binder, and adding the binder to water at 60-100° C. and allowing it to fully react to prepare a binder; The cross-linking agent is methyl acetoacetate; The mass ratio of PVA powder to cross-linking agent is 1:(0.10-0.30); S2: Preparation of composite slurry Weighing ceramic particles into a second mixer, adding a dispersant to the second mixer, and mixing uniformly to prepare a second mixture, adding the second mixture into water to prepare a pre-slurry, adding the binder prepared in step S1 into the pre-slurry, and mixing and stirring to prepare a composite slurry; S3: Preparation of lithium-ion battery separators The composite slurry is coated on both sides of the diaphragm body using a roller coater, and the diaphragm body coated with the composite slurry is dried to form a diaphragm coating on both sides of the diaphragm body to prepare a lithium ion battery diaphragm.

2. The method for preparing a lithium-ion battery separator with a low transverse curling rate according to claim 1, characterized in that: In step S1, the mass ratio of the binder to water is 1:(8-10).

3. The method for preparing a lithium-ion battery separator with a low transverse curling rate according to claim 1, characterized in that: In step S1 and step S2, the water is deionized water.

4. The method for preparing a lithium-ion battery separator with a low transverse curling rate according to claim 1, characterized in that: In step S2, the D50 of the ceramic particles is not greater than 1.2 μm.

5. The method for preparing a lithium-ion battery separator with a low transverse curling rate according to claim 1, characterized in that: In step S2, the dispersant is any one or more of polyacrylic acid sodium salt and polytetrafluoroethylene mixed in any proportion; The mass ratio of the ceramic particles to the dispersant is (100-140):

1.

6. The method for preparing a lithium-ion battery separator with a low transverse curling rate according to claim 1, characterized in that: In step S2, the mass ratio of the second mixture to water is (0.6-1.0):1; The mass ratio of the binder to the pre-slurry is 1:(3-5).

7. The method for preparing a lithium-ion battery separator with a low transverse curling rate according to claim 1, characterized in that: In step S2, during the mixing and stirring process, the mixing and stirring rate is 30-40 rpm / min, and the mixing and stirring time is 30-50 min.

8. The method for preparing a lithium-ion battery separator with a low transverse curling rate according to claim 1, characterized in that: In step S3, the coating rate of the roller coater is 120-160 m / min; In step S3, the coating pressure is 0.5-0.6 MPa, and the coating gap is 3-5 μm.

9. The method for preparing a lithium-ion battery separator with a low transverse curling rate according to claim 1, characterized in that: In step S3, during the drying process, the drying temperature is 60-70° C. and the drying time is 10-20 minutes.

10. A lithium-ion battery separator with a low transverse curling rate, characterized in that: The lithium-ion battery separator is prepared by the preparation method of the lithium-ion battery separator with low transverse curling rate according to any one of claims 1 to 9.

Images