Highly infiltrated lithium-ion battery separator and method of making same

Abstract

This invention discloses a highly wettable lithium-ion battery separator and its preparation method. The highly wettable lithium-ion battery separator comprises a base film and a coating on the base film. The coating comprises polyvinylpyrrolidone, sodium dodecyl diphenyl ether disulfonate, sodium carboxymethyl cellulose, polyacrylonitrile, and polyvinyl alcohol. This invention prepares a slurry through a rational ratio of multiple dispersants and two non-fluorinated binders, combined with matrix-style dot coating, effectively reducing the surface tension of the liquid and allowing the liquid to penetrate more easily into the separator, significantly improving the electrolyte wettability of the lithium-ion battery separator. Good wettability helps improve ion transport efficiency, reduce internal resistance, and thus enhance the overall performance and stability of the battery.

Description

Technical Field

[0001] This invention belongs to the field of battery separator technology, specifically relating to a highly wettable lithium-ion battery separator and its preparation method. Background Technology

[0002] Lithium-ion batteries, with their high energy density and long lifespan, are a crucial technology for modern energy storage and are widely used in electric vehicles, portable electronic devices, and energy storage systems. However, the safety and electrolyte wettability of lithium-ion batteries are key factors affecting their performance and lifespan. In the manufacturing process of lithium-ion batteries, the separator, as a vital component, plays a crucial role in isolating the positive and negative electrodes and preventing short circuits. Simultaneously, the separator needs to possess good electrolyte wettability to ensure smooth ion transport through it, thereby improving the overall efficiency and stability of the battery. Therefore, improving the wettability of the separator is of great significance for enhancing the performance of lithium-ion batteries. Summary of the Invention

[0003] In view of the shortcomings of the prior art, the purpose of this invention is to provide a lithium-ion battery separator with high wettability.

[0004] Another object of the present invention is to provide a method for preparing the above-mentioned highly wettable lithium-ion battery separator.

[0005] Another object of the present invention is to provide a slurry.

[0006] Another object of the present invention is to provide a method for preparing the above-mentioned slurry, wherein the slurry is obtained by dispersing a non-fluorinated binder with multiple dispersants.

[0007] The objective of this invention is achieved through the following technical solution.

[0008] A highly wettable lithium-ion battery separator includes: a base film and a coating on the base film, wherein the coating comprises: polyvinylpyrrolidone, sodium dodecyl diphenyl ether disulfonate, sodium carboxymethyl cellulose, polyacrylonitrile and polyvinyl alcohol, and the ratio of polyvinylpyrrolidone, sodium dodecyl diphenyl ether disulfonate, sodium carboxymethyl cellulose, polyacrylonitrile and polyvinyl alcohol by mass parts is (1-5):(1-5):(160-180):(180-200):(180-200).

[0009] In the above technical solution, the preferred ratio of polyvinylpyrrolidone, sodium dodecyl diphenyl ether disulfonate, sodium carboxymethyl cellulose, polyacrylonitrile and polyvinyl alcohol by mass parts is (2-5):(2-5):(170-180):(190-200):(190-200).

[0010] In the above technical solution, the thickness of the coating is 4 to 5 micrometers.

[0011] The above-mentioned method for preparing a high wettability lithium-ion battery separator includes: applying a slurry onto a base film by dot coating, drying, and obtaining a coating on the base film to obtain a high wettability lithium-ion battery separator.

[0012] A slurry comprising: water, a dispersant, and a non-fluorinated binder, wherein the dispersant is a mixture of polyvinylpyrrolidone, sodium dodecyl diphenyl ether disulfonate, and sodium carboxymethyl cellulose, and the non-fluorinated binder is a mixture of polyacrylonitrile and polyvinyl alcohol, wherein the ratio of water, polyvinylpyrrolidone, sodium dodecyl diphenyl ether disulfonate, sodium carboxymethyl cellulose, polyacrylonitrile, and polyvinyl alcohol, by mass parts, is (1600–2400):(1–5):(1–5):(160–180):(180–200):(180–200).

[0013] In the above technical solution, the preferred ratio of water, polyvinylpyrrolidone, sodium dodecyl diphenyl ether disulfonate, sodium carboxymethyl cellulose, polyacrylonitrile and polyvinyl alcohol by mass is (2000-2400):(2-5):(2-5):(170-180):(190-200):(190-200).

[0014] The method for preparing the above-mentioned slurry includes the following steps:

[0015] Step 1: Mix water and polyvinylpyrrolidone, emulsify, and obtain the first substance;

[0016] Step 2: Mix the first substance with sodium dodecyl diphenyl ether disulfonate and emulsify to obtain the second substance;

[0017] Step 3: Mix the second substance with sodium carboxymethyl cellulose and emulsify to obtain the third substance;

[0018] Step 4: Mix the third substance with polyacrylonitrile and emulsify to obtain the fourth substance;

[0019] Step 5: Mix the fourth substance with polyvinyl alcohol and emulsify to obtain a slurry;

[0020] The emulsification conditions in steps 1 to 3 are: stirring at 50 to 60°C under vacuum for 15 to 30 minutes. The emulsification conditions in steps 4 to 5 are: stirring at 50 to 60°C under vacuum for 20 to 30 minutes.

[0021] In steps 1 to 3, the emulsification conditions are as follows: stirring at 50 to 60°C in a vacuum environment with a rotation speed of 1800 to 2000 r / min and a revolution speed of 40 to 50 r / min for 15 to 30 minutes, and the vacuum degree of the vacuum environment is -0.095 to -0.08 MPa.

[0022] In steps 4 and 5, the emulsification conditions are as follows: stirring at 50-60°C and in a vacuum environment at a rotation speed of 2500-2800 r / min and a revolution speed of 42-52 r / min for 20-30 minutes, with a vacuum degree of -0.09 to -0.08 MPa.

[0023] In the method for preparing the slurry, the ratio of water, polyvinylpyrrolidone, sodium dodecyl diphenyl ether disulfonate, sodium carboxymethyl cellulose, polyacrylonitrile, and polyvinyl alcohol is (1600-2400):(1-5):(1-5):(160-180):(180-200):(180-200), preferably: by mass parts, the ratio of water, polyvinylpyrrolidone, sodium dodecyl diphenyl ether disulfonate, sodium carboxymethyl cellulose, polyacrylonitrile, and polyvinyl alcohol is preferably (2000-2400):(2-5):(2-5):(170-180):(190-200):(190-200).

[0024] Application of polyvinylpyrrolidone, sodium dodecyl diphenyl ether disulfonate, sodium carboxymethyl cellulose, polyacrylonitrile, and polyvinyl alcohol in synergistic improvement of membrane wettability.

[0025] Applications of polyvinylpyrrolidone, sodium dodecyl diphenyl ether disulfonate, sodium carboxymethyl cellulose, polyacrylonitrile, and polyvinyl alcohol in synergistic improvement of diaphragm liquid absorption rate, liquid retention rate, and / or ionic conductivity.

[0026] Emulsification with water and polyvinylpyrrolidone (a nonionic dispersant) increases the solubility of water-soluble organic matter. The subsequent addition of sodium dodecyl diphenyl ether disulfonate (anionic dispersant) enhances the system's surface activity and solubility. The addition of sodium carboxymethyl cellulose increases the system's viscosity and stability. The sequential addition of these dispersants further enhances the system's solubility and surface activity, facilitating the dissolution of subsequent organic binders and resulting in a more homogeneous system. Polyacrylonitrile is then added, followed by polyvinyl alcohol. The hydroxyl groups in the polyvinyl alcohol chains increase the van der Waals forces of the system, further enhancing the slurry's stability.

[0027] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0028] 1. Improved Separator Wetting: A slurry prepared by rationally proportioning multiple dispersants and two non-fluorinated binders, combined with matrix-style dot coating, effectively reduces the surface tension of the liquid, allowing it to penetrate the separator more easily and significantly improving the electrolyte wettability of the lithium-ion battery separator. Good wettability helps improve ion transport efficiency, reduce internal resistance, and thus enhance the overall performance and stability of the battery.

[0029] 2. Enhanced safety: Non-fluorinated binders have lower surface energy, which makes them easier to bond with the base film, helping to improve the safety of lithium-ion batteries and reduce the risks of overcharging, over-discharging, short circuits and thermal runaway, thus ensuring user safety.

[0030] 3. Extended battery life: The slurry combined with the dot-coating method of this invention allows the slurry to be uniformly coated on the surface of the base film, avoiding the phenomenon of excessively thick or thin coating in some areas, thereby improving the air permeability of the separator and extending the service life of the lithium-ion battery.

[0031] 4. Enhanced electrolyte retention: The coating of this invention is a non-fluorinated organic coating with high hydrophilicity, which gives the separator good wettability and electrolyte retention capacity for the electrolyte in the lithium-ion battery. This makes it less likely for the electrolyte to leak out during the charging and discharging process.

[0032] 5. Environmental friendliness: Non-fluorinated coatings are more environmentally friendly than fluorinated coatings.

[0033] 6. This invention employs matrix dot coating, making the coating process more precise and controllable, thereby improving production efficiency and product quality. Detailed Implementation

[0034] The technical solution of the present invention will be further described below with reference to specific embodiments.

[0035] Polyvinylpyrrolidone: a light yellow powder with a density of approximately 1.144 g / cm³. 3 Boiling point: 217.6℃; Melting point: 130℃; Flash point: 93.9℃; Number average molecular weight (Mn): 8971 g / mol. (Shanghai Dibai Chemicals Technology Co., Ltd.)

[0036] Sodium dodecyl diphenyl ether disulfonate: Chemical formula is C 24 H 32 O7S2Na2, molecular weight 542.6, purity 99.0%, density approximately 1.161 g / ml (at 25℃), viscosity 145 MPa·s at 25℃ and concentration 0.1%, Tianjin Xiens Biochemical Technology Co., Ltd.

[0037] Sodium carboxymethyl cellulose: a light yellow powder with a viscosity of 400-800 cP (2% solubility in water at 25℃ test), manufactured by Shanghai Pudong New Area Bide Pharmaceutical Co., Ltd.

[0038] Polyacrylonitrile: White, opaque powder. Density: 1.184 g / mL at 25℃ (lit.). Melting point: 317℃. Glass transition temperature: 85℃. Number-average molecular weight (Mn): 34369 g / mol. (Source: THICA Chemical Industry Development Co., Ltd.)

[0039] Polyvinyl alcohol: The relative density (25℃) of polyvinyl alcohol is 1.29 (solid), and the number average molecular weight (Mn) is 100967 g / mol. Changzhou Qidi Chemical Co., Ltd.

[0040] The test standards for liquid absorption rate and liquid retention rate are QB / T 2303.11—2008, the test standard for wettability is QB / T2303.11—2008, the test standard for contact angle is GB / T 30693-2014, and the test standard for ionic conductivity is GB / T36363-2018.

[0041] In the following examples, the temperature for testing ionic conductivity was 40°C and the relative humidity was 45-50%.

[0042] Increased air permeability: Air permeability of diaphragm - Air permeability of base membrane.

[0043] In the following examples, the base film is a wet-process polyethylene film with a thickness of 7.1 μm and an air permeability of 71 Sec / 100 ml. In this invention, the thickness and air permeability are tested in accordance with GB / T 36363-2018.

[0044] In the following examples, wettability characterizes the affinity between the separator and the electrolyte. A higher wettability value indicates better wettability and stronger liquid absorption and retention, resulting in lower battery internal resistance. The wettability v is calculated using the formula: v = h / t, where h is the wetting height (the height to which the electrolyte penetrates the separator in the vertical direction), in mm, and t is the wetting time, in min.

[0045] The electrolyte used for the contact angle test and wettability test is a mixture of electrolyte and solvent. The electrolyte is lithium hexafluorophosphate, and the solvent is a mixture of ethylene carbonate (EC) and diethyl carbonate (DEC) (the volume ratio of EC to DEC is 1:1). The concentration of the electrolyte in the electrolyte is 1 mol / L.

[0046] Peel strength test: Cut the diaphragm into test samples measuring 3cm*15cm. Apply 3M release tape (2.6cm*15cm) to the center of the diaphragm's coated surface. Roll the test sample with a 2kg roller (rolling forward 4 times to ensure the entire sample is covered, rolling in the same direction only, avoiding back-and-forth rolling). Tear off 5cm of one end of the 3M release tape. Clamp the 3M release tape and diaphragm straight between the upper and lower clamps of the Shimadzu Intelligent Electronic Tensile Testing Machine. The peel strength is then measured. The formula for calculating peel strength is: Average force (N) / Release tape width (cm) * 100%. Testing equipment name and model: Shimadzu Intelligent Electronic Tensile Testing Machine AGS-100N; 3M tape: 3M Scotch 600 (26mm wide). Shimadzu Intelligent Electronic Tensile Testing Machine AGS-100N: Maximum load: 100N, Test speed: 100mm / min. In the following examples, the water used is deionized water.

[0047] Examples 1-2, Example 4 and Comparative Example 1

[0048] A method for preparing a slurry includes the following steps:

[0049] Step 1: Mix water and polyvinylpyrrolidone in a centrifugal vacuum emulsifying tank (Wenzhou Tianwo Machinery Technology Co., Ltd.) and emulsify to obtain the first substance. The emulsification conditions are: stirring at 60℃ and vacuum environment with a rotation speed of 2000 r / min and a revolution speed of 40 r / min for 15 min. The vacuum degree of the vacuum environment is -0.08 MPa.

[0050] Step 2: Add sodium dodecyl diphenyl ether disulfonate to the first substance and emulsify to obtain the second substance. The emulsification conditions are: stirring at 60°C and vacuum environment with a rotation speed of 2000 r / min and a revolution speed of 40 r / min for 15 min. The vacuum degree of the vacuum environment is -0.08 MPa.

[0051] Step 3: Add sodium carboxymethyl cellulose to the second substance and emulsify to obtain the third substance. The emulsification conditions are: stirring at 60°C and vacuum environment with a rotation speed of 2000 r / min and a revolution speed of 40 r / min for 15 min. The vacuum degree of the vacuum environment is -0.08 MPa.

[0052] Step 4: Add polyacrylonitrile to the third substance and emulsify to obtain the fourth substance. The emulsification conditions are: stirring at 60℃ and vacuum environment with a rotation speed of 2800 r / min and a revolution speed of 52 r / min for 30 min. The vacuum degree of the vacuum environment is -0.09 MPa.

[0053] Step 5: Add polyvinyl alcohol to the fourth substance and emulsify to obtain a slurry. The emulsification conditions are: stirring at 60°C and vacuum environment with a rotation speed of 2800 r / min and a revolution speed of 52 r / min for 30 min. The vacuum degree of the vacuum environment is -0.09 MPa.

[0054] The ratio of water, polyvinylpyrrolidone, sodium dodecyl diphenyl ether disulfonate, sodium carboxymethyl cellulose, polyacrylonitrile, and polyvinyl alcohol by mass is X.

[0055] The X values ​​are shown in Table 1.

[0056] Table 1

[0057] slurry X Example 1 2400：5：5：180：200：200 Example 2 1600：1：1：160：180：180 Example 4 2400：1：1：160：180：180 Comparative Example 1 2400：10：5：180：200：200

[0058] Example 3

[0059] A method for preparing a slurry includes the following steps:

[0060] Step 1: Mix water and polyvinylpyrrolidone in a centrifugal vacuum emulsifying tank (Wenzhou Tianwo Machinery Technology Co., Ltd.) and emulsify to obtain the first substance. The emulsification conditions are: stirring at 50℃ and vacuum environment with a rotation speed of 1800 r / min and a revolution speed of 50 r / min for 30 min. The vacuum degree of the vacuum environment is -0.095 MPa.

[0061] Step 2: Add sodium dodecyl diphenyl ether disulfonate to the first substance and emulsify to obtain the second substance. The emulsification conditions are: stirring at 50°C and vacuum environment with a rotation speed of 1800 r / min and a revolution speed of 50 r / min for 30 min. The vacuum degree of the vacuum environment is -0.095 MPa.

[0062] Step 3: Add sodium carboxymethyl cellulose to the second substance and emulsify to obtain the third substance. The emulsification conditions are: stirring at 50°C and vacuum environment with a rotation speed of 1800 r / min and a revolution speed of 50 r / min for 30 min. The vacuum degree of the vacuum environment is -0.095 MPa.

[0063] Step 4: Add polyacrylonitrile to the third substance and emulsify to obtain the fourth substance. The emulsification conditions are: stirring at 50°C and vacuum environment with a rotation speed of 2500 r / min and a revolution speed of 42 r / min for 20 min. The vacuum degree of the vacuum environment is -0.08 MPa.

[0064] Step 5: Add polyvinyl alcohol to the fourth substance and emulsify to obtain a slurry. The emulsification conditions are: stirring at 50°C and vacuum environment with a rotation speed of 2500 r / min and a revolution speed of 42 r / min for 20 min. The vacuum degree of the vacuum environment is -0.08 MPa.

[0065] The ratio of water, polyvinylpyrrolidone, sodium dodecyl diphenyl ether disulfonate, sodium carboxymethyl cellulose, polyacrylonitrile, and polyvinyl alcohol by mass is 2200:3:3:170:190:190.

[0066] Comparative Example 2 (without polyvinylpyrrolidone and sodium dodecyl diphenyl ether disulfonate)

[0067] A method for preparing a slurry includes the following steps:

[0068] Step 1: Mix water and sodium carboxymethyl cellulose in a centrifugal vacuum emulsifying tank (Wenzhou Tianwo Machinery Technology Co., Ltd.) and emulsify to obtain substance A1. The emulsification conditions are: stirring at 60℃ and vacuum environment with a rotation speed of 2000 r / min and a revolution speed of 40 r / min for 15 min. The vacuum degree of the vacuum environment is -0.08 MPa.

[0069] Step 2: Add polyacrylonitrile to substance A1 and emulsify to obtain substance A2. The emulsification conditions are: stirring at 60℃ and vacuum environment with a rotation speed of 2800 r / min and a revolution speed of 52 r / min for 30 min. The vacuum degree of the vacuum environment is -0.09 MPa.

[0070] Step 3: Add polyvinyl alcohol to substance A2 and emulsify to obtain a slurry. The emulsification conditions are: stirring at 60°C and vacuum environment with a rotation speed of 2800 r / min and a revolution speed of 52 r / min for 30 min. The vacuum degree of the vacuum environment is -0.09 MPa.

[0071] The ratio of water, sodium carboxymethyl cellulose, polyacrylonitrile, and polyvinyl alcohol by mass is 2400:180:200:200.

[0072] The slurry prepared in Comparative Example 2 has poor stability and cannot be coated.

[0073] Comparative Example 3 (without sodium carboxymethyl cellulose)

[0074] A method for preparing a slurry includes the following steps:

[0075] Step 1: Mix water and polyvinylpyrrolidone in a centrifugal vacuum emulsifying tank (Wenzhou Tianwo Machinery Technology Co., Ltd.) and emulsify to obtain the first substance. The emulsification conditions are: stirring at 60℃ and vacuum environment with a rotation speed of 2000 r / min and a revolution speed of 40 r / min for 15 min. The vacuum degree of the vacuum environment is -0.08 MPa.

[0076] Step 2: Add sodium dodecyl diphenyl ether disulfonate to the first substance and emulsify to obtain the second substance. The emulsification conditions are: stirring at 60°C and vacuum environment with a rotation speed of 2000 r / min and a revolution speed of 40 r / min for 15 min. The vacuum degree of the vacuum environment is -0.08 MPa.

[0077] Step 3: Add polyacrylonitrile to the second substance and emulsify to obtain substance Y. The emulsification conditions are: stirring at 60℃ and vacuum environment with a rotation speed of 2800 r / min and a revolution speed of 52 r / min for 30 min. The vacuum degree of the vacuum environment is -0.09 MPa.

[0078] Step 4: Add polyvinyl alcohol to substance Y and emulsify to obtain a slurry. The emulsification conditions are: stirring at 60℃ and vacuum environment with a rotation speed of 2800 r / min and a revolution speed of 52 r / min for 30 min. The vacuum degree of the vacuum environment is -0.09 MPa.

[0079] The ratio of water, polyvinylpyrrolidone, sodium dodecyl diphenyl ether disulfonate, polyacrylonitrile, and polyvinyl alcohol by mass is 2400:5:5:200:200.

[0080] The slurry prepared in Comparative Example 3 had poor stability and could not be coated.

[0081] Comparative Example 4 (without polyvinylpyrrolidone)

[0082] A method for preparing a slurry includes the following steps:

[0083] Step 1: Mix water and sodium dodecyl diphenyl ether disulfonate in a centrifugal vacuum emulsifying tank (Wenzhou Tianwo Machinery Technology Co., Ltd.) and emulsify to obtain substance B1. The emulsification conditions are: stirring at 60℃ and vacuum environment with a rotation speed of 2000 r / min and a revolution speed of 40 r / min for 15 min. The vacuum degree of the vacuum environment is -0.08 MPa.

[0084] Step 2: Add sodium carboxymethyl cellulose to substance B1 and emulsify to obtain substance B2. The emulsification conditions are: stirring at 60°C and vacuum environment with a rotation speed of 2000 r / min and a revolution speed of 40 r / min for 15 min. The vacuum degree of the vacuum environment is -0.08 MPa.

[0085] Step 3: Add polyacrylonitrile to substance B2 and emulsify to obtain substance B3. The emulsification conditions are: stirring at 60℃ and vacuum environment with a rotation speed of 2800 r / min and a revolution speed of 52 r / min for 30 min. The vacuum degree of the vacuum environment is -0.09 MPa.

[0086] Step 4: Add polyvinyl alcohol to substance B3 and emulsify to obtain a slurry. The emulsification conditions are: stirring at 60°C and vacuum environment with a rotation speed of 2800 r / min and a revolution speed of 52 r / min for 30 min. The vacuum degree of the vacuum environment is -0.09 MPa.

[0087] The ratio of water, sodium dodecyl diphenyl ether disulfonate, sodium carboxymethyl cellulose, polyacrylonitrile, and polyvinyl alcohol by mass is 2400:5:180:200:200.

[0088] Comparative Example 5 (without sodium dodecyl diphenyl ether disulfonate)

[0089] A method for preparing a slurry includes the following steps:

[0090] Step 1: Mix water and polyvinylpyrrolidone in a centrifugal vacuum emulsifying tank (Wenzhou Tianwo Machinery Technology Co., Ltd.) and emulsify to obtain the first substance. The emulsification conditions are: stirring at 60℃ and vacuum environment with a rotation speed of 2000 r / min and a revolution speed of 40 r / min for 15 min. The vacuum degree of the vacuum environment is -0.08 MPa.

[0091] Step 2: Add sodium carboxymethyl cellulose to the first substance and emulsify to obtain substance C1. The emulsification conditions are: stirring at 60°C and vacuum environment with a rotation speed of 2000 r / min and a revolution speed of 40 r / min for 15 min. The vacuum degree of the vacuum environment is -0.08 MPa.

[0092] Step 3: Add polyacrylonitrile to substance C1 and emulsify to obtain substance C2. The emulsification conditions are: stirring at 60℃ and vacuum environment with a rotation speed of 2800 r / min and a revolution speed of 52 r / min for 30 min. The vacuum degree of the vacuum environment is -0.09 MPa.

[0093] Step 4: Add polyvinyl alcohol to substance C2 and emulsify to obtain a slurry. The emulsification conditions are: stirring at 60°C and vacuum environment with a rotation speed of 2800 r / min and a revolution speed of 52 r / min for 30 min. The vacuum degree of the vacuum environment is -0.09 MPa.

[0094] The ratio of water, polyvinylpyrrolidone, sodium carboxymethyl cellulose, polyacrylonitrile, and polyvinyl alcohol by mass is 2400:5:180:200:200.

[0095] Comparative Example 6 (without polyvinyl alcohol)

[0096] A slurry, which is the fourth substance prepared in Example 1.

[0097] Comparative Example 7 (without polyacrylonitrile)

[0098] A method for preparing a slurry includes: adding polyvinyl alcohol to the third substance of Example 1, emulsifying, and obtaining a slurry. The emulsification conditions are: stirring at 60°C and a vacuum environment with a rotation speed of 2800 r / min and a revolution speed of 52 r / min for 30 min, and the vacuum degree of the vacuum environment is -0.09 MPa. The ratio of water, polyvinylpyrrolidone, sodium dodecyl diphenyl ether disulfonate, sodium carboxymethyl cellulose, and polyvinyl alcohol by mass is 2400:5:5:180:200.

[0099] Comparative Example 8

[0100] A method for preparing a slurry includes the following steps:

[0101] Step 1: Mix water and sodium carboxymethyl cellulose in a centrifugal vacuum emulsifying tank (Wenzhou Tianwo Machinery Technology Co., Ltd.) and emulsify to obtain substance E1. The emulsification conditions are: stirring at 60℃ and vacuum environment with a rotation speed of 2000 r / min and a revolution speed of 40 r / min for 15 min. The vacuum degree of the vacuum environment is -0.08 MPa.

[0102] Step 2: Add sodium dodecyl diphenyl ether disulfonate to substance E1 and emulsify to obtain substance E2. The emulsification conditions are: stirring at 60°C and vacuum environment with a rotation speed of 2000 r / min and a revolution speed of 40 r / min for 15 min. The vacuum degree of the vacuum environment is -0.08 MPa.

[0103] Step 3: Add polyvinylpyrrolidone to substance E2 and emulsify to obtain substance E3. The emulsification conditions are: stirring at 60°C and vacuum environment with a rotation speed of 2000 r / min and a revolution speed of 40 r / min for 15 min. The vacuum degree of the vacuum environment is -0.08 MPa.

[0104] Step 4: Add polyacrylonitrile to substance E3 and emulsify to obtain substance E4. The emulsification conditions are: stirring at 60℃ and vacuum environment with a rotation speed of 2800 r / min and a revolution speed of 52 r / min for 30 min. The vacuum degree of the vacuum environment is -0.09 MPa.

[0105] Step 5: Add polyvinyl alcohol to E4 substance and emulsify to obtain slurry. The emulsification conditions are: stirring at 60℃ and vacuum environment with a rotation speed of 2800 r / min and a revolution speed of 52 r / min for 30 min. The vacuum degree of the vacuum environment is -0.09 MPa.

[0106] The ratio of water, polyvinylpyrrolidone, sodium dodecyl diphenyl ether disulfonate, sodium carboxymethyl cellulose, polyacrylonitrile, and polyvinyl alcohol by mass is 2400:5:5:180:200:200.

[0107] Examples 5-8 and Comparative Examples 9-14

[0108] A method for preparing a lithium-ion battery separator includes: pumping a slurry into a matrix-type dot-coating structure, applying the slurry to one side (any side of a base film) of the base film using a dot-coating method, drying at 80°C for 10 min, and obtaining a coating on the base film to obtain a lithium-ion battery separator. The slurry is one of Examples 1-4, Comparative Examples 1, and Comparative Examples 4-8. The diameter of the coating dots is 330 μm, and the coating dots are arranged in a square, with a side length of 490 μm. The coating amount is 0.5 g / m².

[0109] Table 2

[0110]

[0111]

[0112] Example 9

[0113] A method for preparing a lithium-ion battery separator includes: pumping the slurry prepared in Example 1 into a rotary spray coating structure, coating the slurry on one side (any side of a base film) of the base film by spraying, drying at 80°C for 10 min, and obtaining a coating on the base film to obtain a lithium-ion battery separator. The coating amount is 0.5 g / m².

[0114] The data for the membranes prepared in Examples 5-9 and Comparative Examples 9-14 are as follows (thickness increments are coating thickness):

[0115] Table 3 (The contact angles in Table 3 are the contact angles between the lithium-ion battery separator and the electrolyte)

[0116]

[0117]

[0118] The present invention has been described above by way of example. It should be noted that any simple modifications, alterations or other equivalent substitutions that can be made by those skilled in the art without creative effort without departing from the core of the present invention fall within the protection scope of the present invention.

Claims

1. A highly wettable lithium-ion battery separator, characterized in that, include: The base film and the coating on the base film, wherein the coating comprises: polyvinylpyrrolidone, sodium dodecyl diphenyl ether disulfonate, sodium carboxymethyl cellulose, polyacrylonitrile and polyvinyl alcohol, wherein the ratio of polyvinylpyrrolidone, sodium dodecyl diphenyl ether disulfonate, sodium carboxymethyl cellulose, polyacrylonitrile and polyvinyl alcohol by mass parts is (1-5):(1-5):(160-180):(180-200):(180-200).

2. The high wettability lithium-ion battery separator according to claim 1, characterized in that, The ratio of polyvinylpyrrolidone, sodium dodecyl diphenyl ether disulfonate, sodium carboxymethyl cellulose, polyacrylonitrile and polyvinyl alcohol by mass parts is (2-5):(2-5):(170-180):(190-200):(190-200).

3. The highly wettable lithium-ion battery separator according to claim 1, characterized in that, The coating has a thickness of 4 to 5 micrometers.

4. The method for preparing a highly wettable lithium-ion battery separator according to any one of claims 1 to 3, characterized in that, include: The slurry is coated onto the base film using a dot coating method, and then dried to obtain a coating layer on the base film, resulting in a highly wettable lithium-ion battery separator.

5. A slurry, characterized in that, include: The mixture comprises water, a dispersant, and a non-fluorinated binder, wherein the dispersant is a mixture of polyvinylpyrrolidone, sodium dodecyl diphenyl ether disulfonate, and sodium carboxymethyl cellulose, and the non-fluorinated binder is a mixture of polyacrylonitrile and polyvinyl alcohol. The ratio of water, polyvinylpyrrolidone, sodium dodecyl diphenyl ether disulfonate, sodium carboxymethyl cellulose, polyacrylonitrile, and polyvinyl alcohol by mass is (1600-2400):(1-5):(1-5):(160-180):(180-200):(180-200).

6. The slurry according to claim 5, characterized in that, The ratio of water, polyvinylpyrrolidone, sodium dodecyl diphenyl ether disulfonate, sodium carboxymethyl cellulose, polyacrylonitrile, and polyvinyl alcohol by mass parts is (2000-2400): (2-5): (2-5): (170-180): (190-200): (190-200).

7. A method for preparing the slurry according to any one of claims 5 to 6, characterized in that, Includes the following steps: Step 1: Mix water and polyvinylpyrrolidone, emulsify, and obtain the first substance; Step 2: Mix the first substance with sodium dodecyl diphenyl ether disulfonate and emulsify to obtain the second substance; Step 3: Mix the second substance with sodium carboxymethyl cellulose and emulsify to obtain the third substance; Step 4: Mix the third substance with polyacrylonitrile and emulsify to obtain the fourth substance; Step 5: Mix the fourth substance with polyvinyl alcohol and emulsify to obtain a slurry; The emulsification conditions in steps 1 to 3 are: stirring at 50 to 60°C under vacuum for 15 to 30 minutes. The emulsification conditions in steps 4 to 5 are: stirring at 50 to 60°C under vacuum for 20 to 30 minutes.

8. The method according to claim 7, characterized in that, The ratio of water, polyvinylpyrrolidone, sodium dodecyl diphenyl ether disulfonate, sodium carboxymethyl cellulose, polyacrylonitrile, and polyvinyl alcohol is (1600-2400):(1-5):(1-5):(160-180):(180-200):(180-200).

9. Application of polyvinylpyrrolidone, sodium dodecyl diphenyl ether disulfonate, sodium carboxymethyl cellulose, polyacrylonitrile, and polyvinyl alcohol in synergistic improvement of diaphragm wettability / liquid absorption / liquid retention.

10. Application of polyvinylpyrrolidone, sodium dodecyl diphenyl ether disulfonate, sodium carboxymethyl cellulose, polyacrylonitrile and polyvinyl alcohol in synergistic improvement of membrane ionic conductivity.

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