Storage battery separator and preparation method thereof

Abstract

The invention relates to the technical field of storage batteries, and provides a storage battery separator and a preparation method thereof, in a slurry stirring stage, ionic wind is introduced for aeration treatment, so that the problem of relatively large thickness fluctuation of a traditional AGM separator is effectively solved, and the thickness uniformity and the overall performance of the separator are remarkably improved. The technical scheme has innovativeness and practicability, and a new thought and method are provided for preparation of the storage battery separator.

Description

Technical Field

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

[0002] Battery separator is a thin sheet of insulating material used to separate the positive and negative plates of lead-acid batteries. It can prevent short circuit between the positive and negative plates of lead-acid batteries and prevent the gyrostasis of positive active substances. It can also adsorb and fix electrolyte to ensure the discharge capacity of the battery.

[0003] Traditional AGM separators are formed by a wet molding process. The fiber slurry is vacuum dehydrated and then pressed into shape. However, the AGM separators after molding generally have large thickness fluctuations. The main reason for the large thickness fluctuations is the uneven distribution of glass fibers. On the one hand, the fiber distribution may be uneven during the slurry preparation stage. Secondly, during the molding stage, the concentration of the net and the proportion of the fiber arrangement direction will also affect the uniformity of the fiber distribution. In addition, during the drying stage, improper control of the drying conditions may also cause uneven shrinkage of the separator surface, thereby affecting the thickness uniformity. From the perspective of raw materials, the thickness, ratio and type of glass fibers may affect the uniformity of distribution.

[0004] In view of this, how to improve the thickness uniformity of battery separators has become one of the technical problems that need to be solved urgently. Summary of the invention

[0005] In view of this, the present invention proposes a battery separator and a preparation method thereof, aiming to improve the thickness uniformity of the battery separator by improving the preparation process.

[0006] The technical solution of the present invention is implemented as follows: The present invention provides a method for preparing a battery separator, comprising the following steps:

[0007] Step 1: Mix the fiber raw materials into slurry and adjust the pH value to 2-3;

[0008] Step 2: introducing ionized air into the slurry for aeration and stirring;

[0009] Step 3, the slurry after ion wind aeration and stirring is flow-formed, vacuum dewatered and roller-pressed to obtain a wet partition;

[0010] Step 4: Dry the wet separator to obtain a battery separator.

[0011] In the above embodiment, the high-energy ions and gas molecules in the ion wind can disturb the fibers in the slurry, making the fibers more evenly distributed in the slurry. The aeration and stirring effect of the ion wind can reduce the agglomeration of fibers in the slurry and improve the overall uniformity of the slurry, thereby forming a partition with a more uniform thickness during the molding process.

[0012] Ion wind is mainly generated by an ion fan, and the gas source is air.

[0013] In some embodiments, in step 2, the air intake volume of the ion wind is 5-15m 3 / min, ion concentration is 10 12 -10 14 ions / cm 3 , aeration and stirring time is 5-10min.

[0014] In some embodiments, in step 1, before preparing the slurry, the step further includes subjecting the fiber raw material to surface plasma treatment.

[0015] In the above embodiment, high-energy particles (such as electrons, ions, free radicals, etc.) in the plasma can interact with atoms and molecules on the fiber surface, destroy the chemical bonds on the surface, and generate a large number of free radicals and polar groups. Plasma treatment can etch the fiber surface, forming tiny pits and rough structures, increasing the specific surface area of ​​the fiber. The increase in surface roughness and the introduction of polar groups increase the surface energy of the fiber, thereby enhancing the wettability and bonding between the fiber and other components in the slurry.

[0016] In some embodiments, the plasma treatment method includes placing the fiber raw material in a plasma treatment device, subjecting the fiber raw material to plasma treatment for 10-60 seconds, with a plasma temperature of 25-40° C., and using an inert gas as a plasma gas source, such as argon, helium, and the like.

[0017] In some embodiments, in step 1, the fiber raw material includes at least one of high-alkali glass fiber and medium-alkali glass fiber.

[0018] In some embodiments, in step 1, a sulfuric acid solution is used to adjust the pH value.

[0019] In some embodiments, in step 2, the slurry concentration before aeration and stirring is 10-15 g / L.

[0020] In some embodiments, in step three, the vacuum degree of vacuum dehydration is 0.015-0.020 MPa.

[0021] In some embodiments, in step 4, the drying temperature is 165-175° C., and the drying is stopped until the moisture content does not exceed 5%.

[0022] In a second aspect, the present invention also provides a battery separator prepared by the above preparation method.

[0023] Compared with the prior art, the present invention has the following beneficial effects:

[0024] The preparation method of the battery separator provided by the present invention introduces ion wind aeration stirring and surface plasma treatment of fiber raw materials in the preparation process. The ion wind aeration stirring can promote the uniform dispersion of fibers in the slurry and reduce the fiber agglomeration phenomenon, thereby improving the thickness uniformity of the separator. The plasma treatment can increase the polar groups on the fiber surface, improve the surface activity and wettability of the fiber, and further promote the uniform distribution of the fiber in the slurry. By optimizing the dispersion and surface activity of the fiber, the pore structure of the separator is more uniform, which helps to improve the adsorption and fixation capacity of the electrolyte, thereby improving the discharge capacity and cycle life of the battery. The introduction of ion wind aeration stirring and plasma treatment makes the preparation of the slurry and the molding process of the separator more efficient, reducing the energy consumption and time cost in the production process. It effectively solves the problem of large thickness fluctuations of traditional AGM separators and significantly improves the thickness uniformity and overall performance of the separator. This technical solution is innovative and practical, and provides new ideas and methods for the preparation of battery separators. DETAILED DESCRIPTION

[0025] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. 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 creative work are within the scope of protection of the present invention.

[0026] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the art to which the embodiments of the present invention belong. If the definitions set forth in this section are contrary to or otherwise inconsistent with the definitions set forth in the patents, patent applications, published patent applications, and other publications incorporated herein by reference, the definitions listed in this section take precedence over the definitions incorporated herein by reference.

[0027] Unless otherwise specified, the methods used in the following examples are all conventional methods. Unless otherwise specified, the materials, reagents and instruments used are all conventional materials, reagents and instruments in the art, and can be obtained by those skilled in the art through commercial channels.

[0028] Example 1.

[0029] This embodiment provides a specific preparation method of a battery separator and a battery separator

[0030] The raw materials include 70 wt% of high-alkali glass fibers and 30 wt% of medium-alkali glass fibers, wherein the average diameter of the high-alkali glass fibers is 1.2 μm, and the average diameter of the medium-alkali glass fibers is 2.5 μm.

[0031] The fiber was mixed with deionized water to form a slurry, and a sulfuric acid solution was added to adjust the pH value to 2.5, the slurry concentration to 12 g / L, and the slurry volume to 120 L.

[0032] Ionized air is introduced into the slurry for aeration and stirring. The air intake of the ionized air is 10m 3 / min, where the ion concentration is 10 13 ions / cm 3 , aeration and stirring treatment for 10 minutes to obtain the aerated and stirred slurry.

[0033] The aerated and stirred slurry is sent to a mesh belt for forming, and after vacuum dehydration at 0.015 MPa, it is rolled to obtain a wet partition.

[0034] The wet separator is dried at 170° C. until the water content does not exceed 5%, and the drying is stopped to obtain a battery separator.

[0035] Example 2

[0036] This embodiment provides a specific preparation method of a battery separator and a battery separator

[0037] The raw materials include 70 wt% of high-alkali glass fibers and 30 wt% of medium-alkali glass fibers, wherein the average diameter of the high-alkali glass fibers is 1.2 μm, and the average diameter of the medium-alkali glass fibers is 2.5 μm.

[0038] First, the high-alkali glass fiber and the medium-alkali glass fiber are laid flat and sent into a plasma treatment device. Argon is used as the gas source, the gas flow rate is 50 sccm, the power is 400 W, and low-temperature plasma treatment is performed. The treatment time is 40 s and the plasma temperature is 30°C.

[0039] The plasma-treated fibers were mixed with deionized water to form a slurry, and a sulfuric acid solution was added to adjust the pH value to 2.5, the slurry concentration to 12 g / L, and the slurry volume to 120 L.

[0040] Ionized air is introduced into the slurry for aeration and stirring. The air intake of the ionized air is 10m 3 / min, where the ion concentration is 10 13 ions / cm 3 , aeration and stirring treatment for 10 minutes to obtain the aerated and stirred slurry.

[0041] The aerated and stirred slurry is sent to a mesh belt for forming, and after vacuum dehydration at 0.015 MPa, it is rolled to obtain a wet partition.

[0042] The wet separator is dried at 170° C. until the water content does not exceed 5%, and the drying is stopped to obtain a battery separator.

[0043] Comparative Example 1

[0044] This comparative example provides a specific preparation method of a battery separator and a battery separator

[0045] The raw materials include 70 wt% of high-alkali glass fibers and 30 wt% of medium-alkali glass fibers, wherein the average diameter of the high-alkali glass fibers is 1.2 μm, and the average diameter of the medium-alkali glass fibers is 2.5 μm.

[0046] The fiber was mixed with deionized water to form a slurry, and a sulfuric acid solution was added to adjust the pH value to 2.5, the slurry concentration to 12 g / L, and the slurry volume to 120 L.

[0047] Air is introduced into the slurry for aeration and stirring, and the air intake volume is 10m 3 / min, and aerate and stir for 10min to obtain the aerated and stirred slurry.

[0048] The aerated and stirred slurry is sent to a mesh belt for forming, and after vacuum dehydration at 0.015 MPa, it is rolled to obtain a wet partition.

[0049] The wet separator is dried at 170° C. until the water content does not exceed 5%, and the drying is stopped to obtain a battery separator.

[0050] Comparative Example 2

[0051] This comparative example provides a specific preparation method of a battery separator and a battery separator

[0052] The raw materials include 70 wt% of high-alkali glass fibers and 30 wt% of medium-alkali glass fibers, wherein the average diameter of the high-alkali glass fibers is 1.2 μm, and the average diameter of the medium-alkali glass fibers is 2.5 μm.

[0053] First, the high-alkali glass fiber and the medium-alkali glass fiber are laid flat and sent into a plasma treatment device. Argon is used as the gas source, the gas flow rate is 50 sccm, the power is 400 W, and low-temperature plasma treatment is performed. The treatment time is 40 s and the plasma temperature is 30°C.

[0054] The plasma-treated fibers were mixed with deionized water to form a slurry, and a sulfuric acid solution was added to adjust the pH value to 2.5, the slurry concentration to 12 g / L, and the slurry volume to 120 L.

[0055] Air is introduced into the slurry for aeration and stirring, and the air intake volume is 10m 3 / min, and aerate and stir for 10min to obtain the aerated and stirred slurry.

[0056] The aerated and stirred slurry is sent to a mesh belt for forming, and after vacuum dehydration at 0.015 MPa, it is rolled to obtain a wet partition.

[0057] The wet separator is dried at 170° C. until the water content does not exceed 5%, and the drying is stopped to obtain a battery separator.

[0058] The battery separators prepared in the above different embodiments and comparative examples were tested for thickness. A laser thickness gauge was used to test the thickness of each battery separator at multiple points, and the average thickness, standard deviation and range were calculated. The test results are shown in the following table:

[0059] Average thickness / mm Standard deviation / mm Range / mm Example 1 3.23 0.02 0.11 Example 2 3.22 0.01 0.05 Comparative Example 1 3.21 0.12 0.28 Comparative Example 2 3.22 0.08 0.22

[0060] In the above embodiments and comparative examples, the relevant parameter conditions of the slurry flow forming and roller pressing operations are consistent.

[0061] It is not difficult to see from the results in the above table that a battery separator with more uniform thickness can be obtained by adopting the preparation process of the present invention.

[0062] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for preparing a battery separator, characterized in that: The steps include: Step 1: Mix the fiber raw materials into slurry and adjust the pH value to 2-3; Step 2: introducing ionized air into the slurry for aeration and stirring; Step 3, the slurry after ion wind aeration and stirring is flow-formed, vacuum dewatered and roller-pressed to obtain a wet partition; Step 4: Dry the wet separator to obtain a battery separator.

2. The method for preparing a battery separator according to claim 1, characterized in that: In step 2, the air intake of the ion wind is 5-15m 3 / min, ion concentration is 10 12 -10 14 ions / cm 3 , aeration and stirring time is 5-10min.

3. The method for preparing a battery separator according to claim 1, characterized in that: In step one, before preparing the slurry, the fiber raw material is also subjected to surface plasma treatment.

4. The method for preparing a battery separator according to claim 3, characterized in that: The plasma treatment method comprises placing the fiber raw material in a plasma treatment device, subjecting the fiber raw material to plasma treatment for 10-60 seconds, and the plasma temperature is 25-40°C.

5. The method for preparing a battery separator according to claim 1, characterized in that: In step 1, the fiber raw material includes at least one of high-alkali glass fiber and medium-alkali glass fiber.

6. The method for preparing a battery separator according to claim 1, characterized in that: In step 1, the pH value is adjusted with sulfuric acid solution.

7. The method for preparing a battery separator according to claim 1, characterized in that: In step 2, the slurry concentration before aeration and stirring is 10-15 g / L.

8. The method for preparing a battery separator according to claim 1, characterized in that: In step 3, the vacuum degree of vacuum dehydration is 0.015-0.020 MPa.

9. The method for preparing a battery separator according to claim 1, characterized in that: In step 4, the drying temperature is 165-175° C., and the drying is stopped until the moisture content does not exceed 5%.

10. A battery separator, characterized in that: The method is prepared by any one of claims 1 to 9.