Lithium battery composite diaphragm for new energy automobile, preparation process and slurry mixing device

Abstract

The invention discloses a lithium battery composite membrane for a new energy automobile, a preparation process and a slurry mixing device, the lithium battery composite membrane comprises a PE base membrane and a coating membrane, the coating membrane is arranged on the surface of the base membrane, and the coating membrane is prepared from ceramic slurry with the concentration of 20%-50% by weight, PAA slurry with the concentration of 6%-30% by weight and the balance of acidic deionized water; the ceramic slurry comprises inorganic powder, a dispersing agent, a wetting agent, a binding agent, a thickening agent and the balance of acidic deionized water. The PAA slurry comprises PAA, a dispersing agent, a wetting agent, a thickening agent, a binder and the balance of acidic deionized water. According to the preparation method, the ceramic slurry and the PAA slurry are mixed according to a certain proportion under an acidic condition, so that the cohesiveness and the heat resistance of the diaphragm are improved while one-time coating is realized.

Description

Technical Field

[0001] The present invention relates to the technical field of lithium batteries, and in particular to a lithium battery composite diaphragm for new energy vehicles, a preparation process and a slurry mixing device. Background Art

[0002] With the proposal of the dual carbon goals, my country's new energy vehicle industry will replace the traditional automobile industry. China is actively developing and supporting the electric vehicle industry, and lithium-ion batteries are the main power source for electric vehicles. Lithium-ion batteries have the characteristics of high energy density, light weight, long cycle life, green environmental protection and no memory effect. They are generally composed of positive electrode, negative electrode, electrolyte and diaphragm. As one of the important components of lithium-ion batteries, the diaphragm separates the positive and negative electrodes of the battery to prevent the two electrodes from contacting and short-circuiting, and plays an important role in ensuring the safety of the battery.

[0003] In the process of manufacturing battery cells, the battery material is often too soft and the battery hardness cannot meet the requirements, so the positive and negative electrodes need to be bonded together to improve the battery hardness. The existing diaphragm bonding effect is poor. Therefore, this application provides a lithium battery composite diaphragm for new energy vehicles, a preparation process and a slurry mixing device to meet the needs. Summary of the invention

[0004] The purpose of this application is to provide a lithium battery composite diaphragm for new energy vehicles, a preparation process and a slurry mixing device, aiming to improve the adhesion of the lithium-ion battery diaphragm, while improving the thermal stability of the diaphragm and achieving one-time coating.

[0005] To achieve the above-mentioned purpose, the present application provides the following technical solution: A composite lithium battery diaphragm for new energy vehicles, comprising a PE base film and a coating film, wherein the surface of the base film is provided with a coating film, wherein the coating film comprises a ceramic slurry with a concentration of 20% to 50wt%, a PAA slurry with a concentration of 6% to 30wt%, and the rest is acidic deionized water, with a pH of 5 to 5.5;

[0006] The ceramic slurry is prepared from the following raw materials in weight percentage: 25% to 45wt% inorganic powder, 0.1% to 0.5wt% dispersant, 0.05% to 0.1wt% wetting agent, 2% to 10wt% binder, 0.1% to 0.8wt% thickener, and the rest is acidic deionized water, pH = 5 to 5.5;

[0007] Excessive acidity or alkalinity will affect the performance of the binder, resulting in a decrease in bonding strength. Deionized water with a pH of 5 to 5.5 can provide a stable dispersion environment and help maintain the stability of the slurry. This range can not only ensure the stability of the slurry, but also reduce the negative impact on the performance of the binder. At the same time, it helps the inorganic powder in the ceramic slurry to maintain a stable structure and performance during the coating process. These inorganic powders usually have high thermal stability and can maintain the stability of their shape and size at high temperatures, thereby enhancing the heat resistance of the coating film;

[0008] The PAA slurry is prepared from the following raw materials in weight percentage: PAA with a concentration of 3% to 11wt%, a dispersant with a concentration of 0.07% to 0.35wt%, a wetting agent with a concentration of 0.05% to 0.30wt%, a thickener with a concentration of 4% to 13wt%, a binder with a concentration of 2.0% to 5.0wt%, and the rest is acidic deionized water, pH = 5 to 5.5;

[0009] Excessively strong acidity may destroy the structure of PAA and reduce its performance. At the same time, a slightly acidic environment with a pH of 5 to 5.5 helps PAA interact with certain components in the ceramic slurry to enhance adhesion. In a slightly acidic environment, PAA can maintain the stability and integrity of its molecular chain. This stability helps PAA maintain its adhesion and mechanical properties at high temperatures, thereby enhancing the heat resistance of the coating film. At the same time, a slightly acidic environment can also reduce the thermal decomposition or degradation reaction of PAA at high temperatures, avoiding the production of by-products that are not conducive to heat resistance.

[0010] As a preferred implementation in this example, the inorganic powder includes one or more of aluminum oxide, boehmite, silicon oxide, zirconium oxide, magnesium oxide, titanium oxide and barium sulfate powder.

[0011] As a preferred implementation in this example, the dispersant includes one or more of a nonionic surfactant or a polycarboxylate ammonium salt.

[0012] As a preferred implementation in this example, the wetting agent includes one or more of polyoxyethylene, silicone-modified silicone oil, fatty alcohol, nonionic surfactant, and siloxane.

[0013] As a preferred implementation in this example, the binder includes one or more of acrylate polymer emulsion, sodium carboxymethyl cellulose, hydroxyethyl cellulose, hydroxypropyl methyl cellulose, polyethylene oxide, polyvinyl alcohol and styrene-butadiene rubber.

[0014] As a preferred implementation in this example, the thickener includes one or more of methyl cellulose, ethyl cellulose, hydroxyethyl cellulose, nonionic polyurethane, polyanionic cellulose, anionic acrylate copolymer emulsion and sodium carboxymethyl cellulose.

[0015] The preparation process of the composite diaphragm of lithium battery for new energy vehicles includes the following steps:

[0016] S1. preparing ceramic slurry: adding a thickener to a slurry mixing device loaded with acidic deionized water, adding inorganic powder after the first mixing, adding a binder after the second mixing and grinding, adding a wetting agent after the third mixing, adding a dispersant after the fourth mixing, and obtaining a ceramic slurry after the fifth mixing;

[0017] S2. preparing PAA slurry: adding a binder to a slurry mixing device loaded with acidic deionized water, adding a dispersant after the first mixing, adding a wetting agent after the second mixing, adding PAA after the third mixing, adding a thickener after the fourth mixing and grinding, and obtaining PAA slurry after the fifth mixing;

[0018] S3, preparation of ceramic and PAA mixed coating slurry: adding the prepared ceramic slurry and PAA slurry into a slurry mixing device loaded with acidic deionized water to mix and disperse to obtain ceramic and PAA mixed coating slurry;

[0019] S4. Preparation of ceramic and PAA mixed coating diaphragm: The prepared diaphragm slurry is coated on a PE diaphragm, and the coated diaphragm is obtained by baking and rolling.

[0020] As a preferred implementation in this embodiment, a slurry mixing device is used in the preparation process of lithium battery composite diaphragms for new energy vehicles, including a large mixing tank and two small mixing tanks located in the large mixing tank, the large mixing tank and the two small mixing tanks are respectively equipped with a second stirring shaft and a first stirring shaft, the upper ends of the two first stirring shafts are fixedly sleeved with a first gear, the bottoms of the large mixing tank and the two small mixing tanks are both provided with a discharge pipe, and the discharge pipes are both provided with an electric valve, the upper ends of the two first stirring shafts are connected by a connecting rod, the lower end of the connecting rod is fixed with a toothed plate, and the toothed plate is gear-engaged with a connecting gear rotatably arranged in the inner cavity of the large mixing tank;

[0021] The large mixing tank is provided with three groups of liquid inlet pipes and two groups of feeding funnels, the liquid outlet ends of the three groups of liquid inlet pipes are respectively located in the inner cavities corresponding to the large mixing tank and the two small mixing tanks, and the discharge ends of the two groups of feeding funnels are respectively located in the inner cavities corresponding to the small mixing tanks;

[0022] A servo motor is installed at the upper end of the mixing tank, and the output end of the servo motor is connected to a driving shaft arranged in the inner cavity of the mixing tank, a first spline shaft is arranged below the driving shaft, and the upper end of the first spline shaft is slidably arranged in the inner cavity of the driving shaft, and a second gear is fixedly installed at the lower end of the first spline shaft;

[0023] A gear ring is fixed to the upper end of the second stirring shaft, and the second stirring shaft is rotatably connected to the inner wall of the mixing tank through a mounting plate;

[0024] A rotating drum is rotatably arranged on the outer wall of the first spline shaft, and the rotating drum is gear-engaged with the connecting gear;

[0025] A driving gear is fixed on the driving shaft, and transmission gears are rotatably arranged on both sides of the driving gear, and the driving gear is gear-engaged with the two transmission gears;

[0026] Mounting blocks are provided on both sides of the small mixing tank, and the mounting blocks are fixedly connected to the inner cavity wall of the large mixing tank. A mounting hole is provided at the upper end of the mounting block, and a lifting spring is fixed in the mounting hole. The upper end of the lifting spring is located above the mounting block and is fixedly connected to the side plate corresponding to the outer wall of the small mixing tank. A limit rod is slidably provided in the inner cavity of the mounting block, and the upper end of the limit rod is fixedly connected to the outer wall of the small mixing tank.

[0027] Initially, the first gear is located above the two transmission gears, and the second gear is located in the inner cavity of the gear ring and is gear-engaged with the gear ring.

[0028] As a preferred implementation in this embodiment, a gravity gear unit is further provided, which is used to make the second gear and the gear ring gear engage in advance to mix the slurry;

[0029] The gravity gear connection unit comprises a second spline shaft, a gravity spring and two groups of tapered material receiving barrels which are wide at the top and narrow at the bottom. The upper end of the second spline shaft is slidably arranged in the inner cavity of the first spline shaft, the second gear is fixed to the lower end of the second spline shaft, a gravity spring is fixed on the second gear, and the upper end of the gravity spring is rotatably connected with the rotating drum, a swivel is rotatably arranged on the second gear, and two groups of mounting frames are relatively arranged on the swivel, the two groups of tapered material receiving barrels are respectively mounted on the corresponding mounting frames, the two groups of tapered material receiving barrels are respectively located directly below the discharge pipes of the corresponding mixing tanks, a tapered cavity is arranged inside the tapered material receiving barrel, and the tapered material receiving barrel is opened at the top and bottom;

[0030] Two groups of columns are fixed on the mounting plate, and the upper ends of the two columns slide through the corresponding mounting frames respectively.

[0031] As a preferred implementation in this embodiment, an automatic opening and closing unit is also provided to control the automatic opening and closing of the discharge opening at the bottom of the conical receiving barrel;

[0032] The automatic opening and closing unit comprises a cross bar which is slidably disposed on the mounting frame, a sealing plate is fixed to the right end of the cross bar, the cross bar is connected to the mounting frame via an opening and closing spring, a baffle is fixed to the left end of the cross bar, and a block is fixed to the left end of the baffle, and a guide inclined surface is provided on the block protrusion;

[0033] Both side ends of the mounting plate are fixed with a resistance rod, and two groups of the resistance rods are respectively matched with the corresponding stop blocks.

[0034] In summary, the technical effects and advantages of the present invention are as follows:

[0035] 1. The structure of the present invention is reasonable. The present invention mixes the ceramic slurry and the PAA slurry in a certain proportion under acidic conditions, thereby achieving one-time coating and improving the adhesion and heat resistance of the diaphragm;

[0036] 2. In the present invention, a group of servo motors are used to automatically switch and drive the stirring shaft that needs to work to rotate and stir without stopping the machine, thereby reducing the number of motors used and reducing costs, while also avoiding frequent starting and stopping of the motors to affect the service life of the motors and increase energy consumption, and also avoiding unnecessary troubles caused by manual switching;

[0037] 3. In the present invention, a gravity gear unit is provided to drive the second stirring shaft to rotate in advance, thereby improving the slurry mixing efficiency and reducing the mixing time;

[0038] 4. In the present invention, an automatic opening and closing unit is provided, which can further realize the rotation of the second stirring shaft in advance, thereby further improving the slurry mixing efficiency and further reducing the mixing time. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For those skilled in the art, other drawings can be obtained based on these drawings without paying any creative work.

[0040] Figure 1 This is a scanning electron microscope image of the ceramic and PAA mixed coating membrane prepared in Example 1;

[0041] Figure 2 It is a schematic diagram of the overall structure of the slurry mixing device;

[0042] Figure 3 for Figure 2 Schematic diagram of the cross-section structure of the medium mixing tank;

[0043] Figure 4 for Figure 3 Schematic diagram of the small mixing tank;

[0044] Figure 5 for Figure 4 The middle partial rear view enlarged structure schematic diagram;

[0045] Figure 6 for Figure 4 A schematic diagram of the partially enlarged structure;

[0046] Figure 7 for Figure 6 Enlarged structural diagram at A in the middle.

[0047] In the figure: 1. large mixing tank; 2. servo motor; 3. small mixing tank; 4. first stirring shaft; 5. liquid inlet pipe; 6. feeding funnel; 7. first gear; 8. transmission gear; 9. driving shaft; 10. driving gear; 11. connecting rod; 12. tooth plate; 13. rotating drum; 14. connecting gear; 15. mounting block; 16. lifting spring; 17. limiting rod; 18. second gear; 19. gear ring; 20. second stirring shaft; 21. first spline shaft; 22. second spline shaft; 23. gravity spring; 24. swivel; 25. mounting frame; 26. column; 27. conical receiving barrel; 28. cross bar; 29. ​​sealing plate; 30. baffle; 31. block; 32. resistance rod; 33. opening and closing spring; 34. guide ramp; 35. mounting plate. DETAILED DESCRIPTION

[0048] The following will be combined with the drawings in 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.

[0049] Example 1

[0050] S1: Preparation of ceramic slurry

[0051] 0.6wt% thickener is added to 60wt% deionized water (acidic, PH=5-5.5), 35wt% inorganic powder is added after the first mixing, 4wt% binder is added after the second mixing and grinding, 0.1wt% wetting agent is added after the third mixing, 0.3wt% dispersant is added after the fourth mixing, and ceramic slurry is obtained after the fifth mixing.

[0052] S2: Preparation of PAA (polyacrylic acid) slurry

[0053] 3.5wt% binder was added to 83wt% deionized water (acidic, PH=5-5.5), 0.3wt% dispersant was added after the first mixing, 0.2wt% wetting agent was added after the second mixing, 6wt% PAA was added after the third mixing, 7wt% thickener was added after the fourth mixing and grinding, and PAA slurry was obtained after the fifth mixing.

[0054] S3: Preparation of ceramic and PAA mixed coating slurry

[0055] 40 wt% of the prepared ceramic slurry, 10 wt% of PAA slurry and 50 wt% of deionized water (acidic, pH=5-5.5) are mixed and dispersed to obtain ceramic and PAA mixed coating slurry.

[0056] S4: Preparation of ceramic and PAA mixed coating membrane

[0057] The prepared mixed slurry was coated on a 9um PE base film, and a 9+3um coated diaphragm was obtained after baking and rolling.

[0058] Example 2

[0059] S1: Preparation of ceramic slurry

[0060] 0.6wt% thickener is added to 60wt% deionized water (acidic, PH=5-5.5), 35wt% inorganic powder is added after the first mixing, 4wt% binder is added after the second mixing and grinding, 0.1wt% wetting agent is added after the third mixing, 0.3wt% dispersant is added after the fourth mixing, and ceramic slurry is obtained after the fifth mixing.

[0061] S2: Preparation of PAA slurry

[0062] 3.5wt% binder was added to 83wt% deionized water (acidic, PH=5-5.5), 0.3wt% dispersant was added after the first mixing, 0.2wt% wetting agent was added after the second mixing, 6wt% PAA was added after the third mixing, 7wt% thickener was added after the fourth mixing and grinding, and PAA slurry was obtained after the fifth mixing.

[0063] S3: Preparation of ceramic and PAA mixed coating slurry

[0064] 30 wt% of the prepared ceramic slurry, 20 wt% of PAA slurry and 50 wt% of deionized water (acidic, pH=5-5.5) are mixed and dispersed to obtain ceramic and PAA mixed coating slurry.

[0065] S4: Preparation of ceramic and PAA mixed coating membrane

[0066] The prepared mixed slurry was coated on a 9um PE base film, and a 9+3um coated diaphragm was obtained after baking and rolling.

[0067] Example 3

[0068] S1: Preparation of ceramic slurry

[0069] 0.6wt% thickener is added to 60wt% deionized water (acidic, PH=5-5.5), 35wt% inorganic powder is added after the first mixing, 4wt% binder is added after the second mixing and grinding, 0.1wt% wetting agent is added after the third mixing, 0.3wt% dispersant is added after the fourth mixing, and ceramic slurry is obtained after the fifth mixing.

[0070] S2: Preparation of PAA slurry

[0071] 3.5wt% binder was added to 83wt% deionized water (acidic, PH=5-5.5), 0.3wt% dispersant was added after the first mixing, 0.2wt% wetting agent was added after the second mixing, 6wt% PAA was added after the third mixing, 7wt% thickener was added after the fourth mixing and grinding, and PAA slurry was obtained after the fifth mixing.

[0072] S3: Preparation of ceramic and PAA mixed coating slurry

[0073] 25 wt% of the prepared ceramic slurry, 25 wt% of the PAA slurry and 50 wt% of deionized water (acidic, pH=5-5.5) are mixed and dispersed to obtain a ceramic and PAA mixed coating slurry.

[0074] S4: Preparation of ceramic and PAA mixed coating membrane

[0075] The prepared mixed slurry was coated on a 9um PE base film, and a 9+3um coated diaphragm was obtained after baking and rolling.

[0076] Example 4

[0077] S1: Preparation of ceramic slurry

[0078] 0.6wt% thickener is added to 60wt% deionized water (acidic, PH=5-5.5), 35wt% inorganic powder is added after the first mixing, 4wt% binder is added after the second mixing and grinding, 0.1wt% wetting agent is added after the third mixing, 0.3wt% dispersant is added after the fourth mixing, and ceramic slurry is obtained after the fifth mixing.

[0079] S2: Preparation of PAA slurry

[0080] 3.5wt% binder was added to 83wt% deionized water (acidic, PH=5-5.5), 0.3wt% dispersant was added after the first mixing, 0.2wt% wetting agent was added after the second mixing, 6wt% PAA was added after the third mixing, 7wt% thickener was added after the fourth mixing and grinding, and PAA slurry was obtained after the fifth mixing.

[0081] S3: Preparation of ceramic and PAA mixed coating slurry

[0082] 20 wt% of the prepared ceramic slurry, 30 wt% of PAA slurry and 50 wt% of deionized water (acidic, pH=5-5.5) are mixed and dispersed to obtain ceramic and PAA mixed coating slurry.

[0083] S4: Preparation of ceramic and PAA mixed coating membrane

[0084] The prepared mixed slurry was coated on a 9um PE base film, and a 9+3um coated diaphragm was obtained after baking and rolling.

[0085] Example 5

[0086] A lithium-ion battery separator was prepared according to the method of Example 1, except that the inorganic powder was replaced with boehmite powder.

[0087] Comparative Example 1

[0088] 0.6wt% thickener was added to 60wt% deionized water, 35wt% inorganic powder was added after the first mixing, 4wt% binder was added after the second mixing and grinding, 0.1wt% wetting agent was added after the third mixing, 0.3wt% dispersant was added after the fourth mixing, and ceramic slurry was obtained after the fifth mixing. The obtained ceramic slurry was coated on a 9um PE base film, and a 9+3um coated diaphragm was obtained after baking and rolling.

[0089] The performance of the lithium ion battery separators obtained in Examples 1-5 of the present invention and Comparative Example 1 was tested, and the test results are shown in Table 1.

[0090] Among them, the test methods / test standards are as follows:

[0091] Thickness: Mahr Millimar C1216 thickness gauge, tested in accordance with GB / T 6672-2001 standard.

[0092] Heat shrinkage: Electric constant temperature blast oven, image measuring instrument, ESPEC GPH-H20, XTY5040, tested in accordance with GB / T363632018 standard.

[0093] Peel strength: Intelligent electronic tensile testing machine, C610M, tested in accordance with GB / T 27911995 standard.

[0094] Table 1 Test results of Examples 1 to 5 and Comparative Example 1

[0095]

[0096] It can be seen from Table 1 that:

[0097] (1) The peel strength of the coated diaphragms prepared by using the ceramic and PAA mixed slurries in Examples 1-5 is higher than the peel strength of the coated diaphragm prepared by using the ceramic slurry in Comparative Example 1, that is, a certain degree of mixing of the ceramic slurry and the PAA slurry helps to improve the peel strength of the coated film;

[0098] (2) The thermal shrinkage (TD and MD) of the coated diaphragms prepared by using the ceramic and PAA mixed slurries in Examples 1-5 are higher than that (TD and MD) of the coated diaphragm prepared by using the ceramic slurry in Comparative Example 1. That is, a certain degree of mixing of the ceramic slurry and the PAA slurry is helpful to improve the heat resistance of the coating film.

[0099] In summary, compared with the existing twice-coated diaphragms and ceramic-coated diaphragms, the ceramic and PAA mixed coating slurry prepared in the present application not only has higher adhesion and heat resistance, but also can reduce the coating process, achieve one-time coating, and reduce costs, and has good application prospects in the field of lithium-ion batteries.

[0100] like Figure 1-5 As shown, a slurry mixing device is used in the preparation process of lithium battery composite diaphragm for new energy vehicles, including a large mixing tank 1 and two small mixing tanks 3 located in the large mixing tank 1, the large mixing tank 1 and the two small mixing tanks 3 are respectively installed with a second stirring shaft 20 and a first stirring shaft 4, the upper ends of the two first stirring shafts 4 are fixedly sleeved with a first gear 7, the bottoms of the large mixing tank 1 and the two small mixing tanks 3 are both provided with a discharge pipe, and the discharge pipe is provided with an electric valve, the upper ends of the two first stirring shafts 4 are connected by a connecting rod 11, the lower end of the connecting rod 11 is fixed with a tooth plate 12, and the tooth plate 12 is gear-connected with a connecting gear 14 rotatably arranged in the inner cavity of the large mixing tank 1;

[0101] The large mixing tank 1 is provided with three groups of liquid inlet pipes 5 and two groups of feeding funnels 6. The liquid outlet ends of the three groups of liquid inlet pipes 5 are respectively located in the inner cavities corresponding to the large mixing tank 1 and the two small mixing tanks 3. The outlet ends of the two groups of feeding funnels 6 are respectively located in the inner cavities corresponding to the small mixing tanks 3.

[0102] A servo motor 2 is installed at the upper end of the mixing tank 1, and the output end of the servo motor 2 is connected to a drive shaft 9 arranged in the inner cavity of the mixing tank 1. A first spline shaft 21 is arranged below the drive shaft 9, and the upper end of the first spline shaft 21 is slidably arranged in the inner cavity of the drive shaft 9, and a second gear 18 is fixedly installed at the lower end of the first spline shaft 21;

[0103] A gear ring 19 is fixed to the upper end of the second stirring shaft 20, and the second stirring shaft 20 is rotatably connected to the inner wall of the mixing tank 1 through a mounting plate 35;

[0104] A rotating drum 13 is rotatably disposed on the outer wall of the first spline shaft 21, and the rotating drum 13 is gear-engaged with the connecting gear 14;

[0105] A driving gear 10 is fixed on the driving shaft 9, and transmission gears 8 are rotatably arranged on both sides of the driving gear 10, and the driving gear 10 is gear-engaged with the two transmission gears 8;

[0106] Mounting blocks 15 are provided on both sides of the small mixing tank 3, and the mounting blocks 15 are fixedly connected to the inner cavity wall of the large mixing tank 1. A mounting hole is provided at the upper end of the mounting block 15, and a jacking spring 16 is fixed in the mounting hole. The upper end of the jacking spring 16 is located above the mounting block 15 and is fixedly connected to the side plate of the outer wall of the small mixing tank 3. A limit rod 17 is slidably provided in the inner cavity of the mounting block 15, and the upper end of the limit rod 17 is fixedly connected to the outer wall of the small mixing tank 3.

[0107] Initially, the first gear 7 is located above the two transmission gears 8 , and the second gear 18 is located in the inner cavity of the gear ring 19 and is geared with the gear ring 19 .

[0108] When in use, an appropriate amount of acidic deionized water is added to the two small mixing tanks 3 and the large mixing tank 1 through the liquid inlet pipe 5. During the adding process, due to the continuous increase in the overall weight of the small mixing tanks 3, the two small mixing tanks 3 will move downward, and eventually the side plates on the outer wall will contact the upper end of the mounting block 15, and the small mixing tanks 3 will stop moving. At the same time, the first gear 7 moves downward and eventually engages with the transmission gear 8 (and when the small mixing tank 3 moves downward, it can drive the tooth plate 12 to move downward, and the downward moving tooth plate 12 cooperates with the connecting tooth plate 14 so that the first spline shaft 21 drives the second gear 18 to move upward, and finally completes the plug-in and separation of the second tooth plate 18 and the gear ring 19). At this time, the servo motor 2 can be controlled to drive the drive shaft 9 to rotate. The drive shaft 9 drives the two first stirring shafts 4 to rotate through the cooperation between the drive gear 10, the transmission gear 8 and the first gear 7, and the remaining materials are respectively placed in the corresponding small mixing tanks 3, and the ceramic slurry and PAA slurry are prepared simultaneously (at this time, the second stirring The mixing shaft 20 does not rotate). When the preparation of the porcelain slurry and the PAA slurry is completed, the two slurries can be discharged from the discharge pipe of the mixing tank 3 at the same time, and the discharged slurry accumulates at the bottom of the mixing tank 1. As the slurry in the mixing tank 3 is discharged, the overall weight of the mixing tank 3 decreases. Under the action of the elastic force of the connecting spring 16, the first gear 7 moves upward. On the contrary, the rotating first spline shaft 21 will drive the second gear 18 to move downward. Finally, the first gear ring 7 is separated from the transmission gear 8 and restored to its original position, and the second gear 18 will be plugged into the gear ring 19 and drive the second stirring shaft 20 to mix and stir the two slurries. When the two slurries are mixed and stirred, the two groups of first stirring shafts 4 above do not rotate. A group of servo motors 2 are used to automatically switch and drive the stirring shaft that needs to work to rotate and stir without stopping the machine, thereby reducing the number of motors used and reducing costs. At the same time, it also avoids frequent starting and stopping of the motor to affect the service life of the motor and increase energy consumption, and also avoids unnecessary trouble caused by manual switching.

[0109] It should be noted that, first, the drive gear plug-in ends on the transmission gear 8, the first gear 7, the second gear 8 and the gear ring 19 are all triangular structures, which is conducive to the guided plug-in between the gears; second, the rotating drum 13 is rotatably connected to the first spline shaft 21 through a bearing.

[0110] As a preferred implementation in this embodiment, Figure 5 and Figure 6 As shown, a gravity gear unit is also provided to enable the second gear 18 to be geared with the gear ring 19 in advance to mix the slurry;

[0111] The gravity gear connection unit includes a second spline shaft 22, a gravity spring 23, and two groups of tapered material receiving barrels 27 that are wide at the top and narrow at the bottom. The upper end of the second spline shaft 22 is slidably arranged in the inner cavity of the first spline shaft 21. The second gear 18 is fixed to the lower end of the second spline shaft 22. The gravity spring 23 is fixed to the second gear 18, and the upper end of the gravity spring 23 is rotatably connected to the rotating drum 13. A swivel 24 is rotatably arranged on the second gear 18, and two groups of mounting frames 25 are relatively arranged on the swivel 24. The two groups of tapered material receiving barrels 27 are respectively installed on the corresponding mounting frames 25. The two groups of tapered material receiving barrels 27 are respectively located directly below the discharge pipes of the corresponding mixing tanks 3. A tapered cavity is arranged inside the tapered material receiving barrel 27, and the tapered material receiving barrel 27 is opened at the top and bottom.

[0112] Two groups of columns 26 are fixed on the mounting plate 35, and the upper ends of the two columns 26 slide through the corresponding mounting frames 25. When discharging the mixing tank 3, it takes a certain amount of time for the second gear 18 to be plugged into the gear ring 19, which makes it impossible to mix the two slurries in advance during this period of time, thereby prolonging the mixing time of the subsequent slurries. Therefore, a gravity plug-in unit is set;

[0113] When the mixing tank 3 is discharging (at this time the second gear 18 is disengaged from the gear ring 19), the slurry discharged from its discharge pipe will fall into the conical receiving barrel 27, and the discharge volume per unit time of the opening at the lower end of the conical receiving barrel 27 is smaller than the discharge volume per unit time of the discharge pipe, thereby causing the slurry to accumulate in the conical receiving barrel 27. The weight of the conical receiving barrel 27 becomes heavier and heavier. Under the action of the gravity of the slurry, the rotating second gear 18 will move downward in advance and finally engage with the gear ring 19, driving the second stirring shaft 20 to rotate in advance, thereby improving the slurry mixing efficiency and reducing the mixing time.

[0114] As a preferred implementation in this embodiment, Figure 6 and Figure 7 As shown, an automatic opening and closing unit is also provided to control the automatic opening and closing of the discharge opening at the bottom of the conical receiving barrel 27;

[0115] The automatic opening and closing unit includes a cross bar 28 that slides transversely and penetrates the mounting frame 25. A sealing plate 29 is fixed to the right end of the cross bar 28. The cross bar 28 is connected to the mounting frame 25 through an opening and closing spring 33. A baffle 30 is fixed to the left end of the cross bar 28, and a stopper 31 is fixed to the left end of the baffle 30. A guide slope 34 is protruded on the stopper 31.

[0116] Resistance rods 32 are fixed to both side ends of the mounting plate 35 , and two groups of resistance rods 32 are respectively matched with corresponding stoppers 31 .

[0117] At the beginning, the sealing plate 29 does not block the bottom opening of the conical receiving barrel 27, and the second gear 18 is not engaged with the gear ring 19. When acidic deionized water is added to the mixing tank 3, the second gear 18 moves upward, and finally the sealing plate 29 blocks the bottom opening of the conical receiving barrel 27. At this time, when the mixing tank 3 is discharged, the slurry enters the conical receiving barrel 27. Since the bottom opening of the conical receiving barrel 27 is sealed, the slurry in the conical receiving barrel 27 is quickly accumulated, and the second gear 18 can be quickly plugged with the gear ring 19. When the second gear 18 moves downward, The resistance rod 32 will resist the guide inclined surface 34 and make the cross bar 28 overcome the elastic force of the opening and closing spring 33 to move closer to the mounting plate 34, and finally release the sealing plate 29 from blocking the bottom opening of the conical receiving barrel 27, so that all the internal slurry can flow out. When the mixing tank 3 returns to its original position, the tooth plate 12 cooperates with the connecting gear 14 to make the first spline shaft 21 move downward, so that the stretched gravity spring 23 returns to its original position. The automatic opening and closing unit is provided to further realize the rotation of the second stirring shaft 20 in advance, thereby further improving the slurry mixing efficiency and further reducing the mixing time.

[0118] It should be noted that the capacity of the conical receiving barrel 27 should not be too large, that is, the weight of the second gear 18 moving downward 1 to complete the gear connection by relying on the conical receiving barrel 27 and the internal slurry should not be too large.

[0119] Finally, it should be noted that the above is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, it is still possible for those skilled in the art to modify the technical solutions described in the aforementioned embodiments or to make equivalent substitutions for some of the technical features therein. 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 composite lithium battery diaphragm for new energy vehicles, comprising a PE base film and a coating film, wherein the surface of the base film is provided with a coating film, characterized in that: The coating film is made of ceramic slurry with a concentration of 20% to 50wt%, PAA slurry with a concentration of 6% to 30wt%, and the rest is acidic deionized water with a pH of 5 to 5.5; The ceramic slurry is prepared from the following raw materials in weight percentage: 25% to 45wt% inorganic powder, 0.1% to 0.5wt% dispersant, 0.05% to 0.1wt% wetting agent, 2% to 10wt% binder, 0.1% to 0.8wt% thickener, and the rest is acidic deionized water, pH = 5 to 5.5; The PAA slurry is prepared from the following raw materials in weight percentage: PAA with a concentration of 3% to 11wt%, a dispersant with a concentration of 0.07% to 0.35wt%, a wetting agent with a concentration of 0.05% to 0.30wt%, a thickener with a concentration of 4% to 13wt%, a binder with a concentration of 2.0% to 5.0wt%, and the rest is acidic deionized water, with a pH of 5 to 5.

5.

2. The composite separator for lithium battery for new energy vehicles according to claim 1, characterized in that: The inorganic powder includes one or more of aluminum oxide, boehmite, silicon oxide, zirconium oxide, magnesium oxide, titanium oxide and barium sulfate powder.

3. The composite separator for lithium battery for new energy vehicles according to claim 1, characterized in that: The dispersant includes one or more of a nonionic surfactant or a polycarboxylate ammonium salt.

4. The composite separator for lithium battery for new energy vehicles according to claim 1, characterized in that: The wetting agent includes one or more of polyoxyethylene, silicone-modified silicone oil, fatty alcohol, nonionic surfactant, and siloxane.

5. The composite separator for lithium battery for new energy vehicles according to claim 1, characterized in that: The binder includes one or more of acrylate polymer emulsion, sodium carboxymethyl cellulose, hydroxyethyl cellulose, hydroxypropyl methyl cellulose, polyethylene oxide, polyvinyl alcohol and styrene-butadiene rubber.

6. The composite separator for lithium battery for new energy vehicles according to claim 1, characterized in that: The thickener includes one or more of methyl cellulose, ethyl cellulose, hydroxyethyl cellulose, nonionic polyurethane, polyanionic cellulose, anionic acrylate copolymer emulsion and sodium carboxymethyl cellulose.

7. The process for preparing the composite separator of lithium battery for new energy vehicles as described in claims 1-6, characterized in that: The steps include: S1. preparing ceramic slurry: adding a thickener to a slurry mixing device loaded with acidic deionized water, adding inorganic powder after the first mixing, adding a binder after the second mixing and grinding, adding a wetting agent after the third mixing, adding a dispersant after the fourth mixing, and obtaining a ceramic slurry after the fifth mixing; S2. preparing PAA slurry: adding a binder to a slurry mixing device loaded with acidic deionized water, adding a dispersant after the first mixing, adding a wetting agent after the second mixing, adding PAA after the third mixing, adding a thickener after the fourth mixing and grinding, and obtaining PAA slurry after the fifth mixing; S3, preparation of ceramic and PAA mixed coating slurry: adding the prepared ceramic slurry and PAA slurry into a slurry mixing device loaded with acidic deionized water to mix and disperse to obtain ceramic and PAA mixed coating slurry; S4. Preparation of ceramic and PAA mixed coating diaphragm: The prepared diaphragm slurry is coated on a PE diaphragm, and the coated diaphragm is obtained by baking and rolling.

8. A slurry mixing device, used in the preparation process of lithium battery composite diaphragm for new energy vehicles, characterized in that: It comprises a large mixing tank (1) and two small mixing tanks (3) located in the large mixing tank (1), wherein the large mixing tank (1) and the two small mixing tanks (3) are respectively provided with a second stirring shaft (20) and a first stirring shaft (4), the upper ends of the two first stirring shafts (4) are fixedly sleeved with a first gear (7), the bottoms of the large mixing tank (1) and the two small mixing tanks (3) are both provided with a discharge pipe, and the discharge pipes are both provided with an electric valve, the upper ends of the two first stirring shafts (4) are connected by a connecting rod (11), the lower end of the connecting rod (11) is fixed with a tooth plate (12), and the tooth plate (12) is gear-connected with a connecting gear (14) rotatably arranged in the inner cavity of the large mixing tank (1); The large mixing tank (1) is provided with three groups of liquid inlet pipes (5) and two groups of feeding funnels (6), the liquid outlet ends of the three groups of liquid inlet pipes (5) are respectively located in the inner cavities corresponding to the large mixing tank (1) and the two small mixing tanks (3), and the discharge ends of the two groups of feeding funnels (6) are respectively located in the inner cavities corresponding to the small mixing tanks (3); A servo motor (2) is installed at the upper end of the mixing tank (1), and the output end of the servo motor (2) is connected to a drive shaft (9) arranged in the inner cavity of the mixing tank (1), a first spline shaft (21) is arranged below the drive shaft (9), and the upper end of the first spline shaft (21) is slidably arranged in the inner cavity of the drive shaft (9), and a second gear (18) is fixedly installed at the lower end of the first spline shaft (21); A gear ring (19) is fixed to the upper end of the second stirring shaft (20), and the second stirring shaft (20) is rotatably connected to the inner wall of the mixing tank (1) via a mounting plate (35); A rotating drum (13) is rotatably arranged on the outer wall of the first spline shaft (21), and the rotating drum (13) is gear-engaged with the connecting gear (14); A driving gear (10) is fixed on the driving shaft (9), and transmission gears (8) are rotatably arranged on both sides of the driving gear (10), and the driving gear (10) is gear-engaged with the two transmission gears (8); Mounting blocks (15) are provided on both sides of the small mixing tank (3), and the mounting blocks (15) are fixedly connected to the inner cavity wall of the large mixing tank (1); a mounting hole is provided at the upper end of the mounting block (15), and a lifting spring (16) is fixed in the mounting hole; the upper end of the lifting spring (16) is located above the mounting block (15) and is fixedly connected to the side plate on the outer wall of the small mixing tank (3); a limiting rod (17) is slidably provided in the inner cavity of the mounting block (15), and the upper end of the limiting rod (17) is fixedly connected to the outer wall of the small mixing tank (3); Initially, the first gear (7) is located above the two transmission gears (8), and the second gear (18) is located in the inner cavity of the gear ring (19) and is gear-engaged with the gear ring (19).

9. A slurry mixing device according to claim 8, characterized in that: A gravity gear coupling unit is also provided, which is used to enable the second gear (18) to engage with the gear ring (19) in advance to mix the slurry; The gravity gear connection unit comprises a second spline shaft (22), a gravity spring (23) and two groups of tapered material receiving barrels (27) which are wider at the top and narrower at the bottom. The upper end of the second spline shaft (22) is slidably arranged in the inner cavity of the first spline shaft (21). The second gear (18) is fixed to the lower end of the second spline shaft (22). The gravity spring (23) is fixed to the second gear (18), and the upper end of the gravity spring (23) is rotatably connected to the rotating drum (13). Then, a rotating ring (24) is rotatably provided on the second gear (18), and two groups of mounting frames (25) are arranged on the rotating ring (24) in a relative manner, and the two groups of the conical material receiving barrels (27) are respectively mounted on the corresponding mounting frames (25), and the two groups of the conical material receiving barrels (27) are respectively located directly below the discharge pipes of the corresponding mixing tanks (3), and a conical cavity is arranged inside the conical material receiving barrels (27), and the conical material receiving barrels (27) are both opened at the top and the bottom; Two groups of columns (26) are fixed on the mounting plate (35), and the upper ends of the two columns (26) slide through the corresponding mounting frames (25) respectively.

10. A slurry mixing device according to claim 9, characterized in that: An automatic opening and closing unit is also provided to control the automatic opening and closing of the discharge opening at the bottom of the conical receiving barrel (27); The automatic opening and closing unit comprises a cross bar (28) which is arranged on the mounting frame (25) and is slidable in a transverse direction. A sealing plate (29) is fixed to the right end of the cross bar (28). The cross bar (28) is connected to the mounting frame (25) via an opening and closing spring (33). A baffle (30) is fixed to the left end of the cross bar (28). A baffle (31) is fixed to the left end of the baffle (30). A guide inclined surface (34) is provided on a protrusion of the baffle (31). Both side ends of the mounting plate (35) are fixed with a resisting rod (32), and two groups of the resisting rods (32) are respectively matched with the corresponding stoppers (31).

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