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

Abstract

The present invention discloses a composite lithium battery separator for new energy vehicles, a preparation process, and a slurry mixing device. The separator comprises a PE base film and a coating film. The base film is provided with a coating film on its surface. The coating film comprises a ceramic slurry at a concentration of 20% to 50% by weight, a PAA slurry at a concentration of 6% to 30% by weight, and the remainder being acidic deionized water. The ceramic slurry comprises an inorganic powder, a dispersant, a wetting agent, a binder, and a thickener, with the remainder being acidic deionized water. The PAA slurry comprises PAA, a dispersant, a wetting agent, a thickener, a binder, and the remainder being acidic deionized water. This application mixes the ceramic slurry and PAA slurry in a certain proportion under acidic conditions, achieving a single coating while simultaneously improving the separator's adhesion and heat resistance.

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] my country's new energy vehicle industry is poised to replace the traditional auto industry, with the country actively developing and supporting the electric vehicle industry. Lithium-ion batteries are the primary power source for electric vehicles. Lithium-ion batteries boast high energy density, lightweight, long cycle life, environmental friendliness, and no memory effect. They are generally composed of a positive electrode, a negative electrode, an electrolyte, and a separator. As a crucial component of lithium-ion batteries, the separator separates the positive and negative electrodes, preventing contact and short circuits, and plays a crucial role in ensuring battery safety.

[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 objectives, the present application provides the following technical solution: a composite separator for lithium batteries 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, and the coating film is made of a ceramic slurry with a concentration of 20% to 50wt%, a PAA slurry with a concentration of 6% to 30wt%, and the rest being 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: inorganic powder with a concentration of 25% to 45wt%, dispersant with a concentration of 0.1% to 0.5wt%, wetting agent with a concentration of 0.05% to 0.1wt%, binder with a concentration of 2% to 10wt%, thickener with a concentration of 0.1% to 0.8wt%, and the rest is acidic deionized water with a pH of 5 to 5.5;

[0007] Excessive acidity or alkalinity will affect the performance of the binder and lead to 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 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 with a pH of 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, enhancing adhesion. In a slightly acidic environment, PAA can maintain the stability and integrity of its molecular chain. This stability helps PAA maintain its bonding and mechanical properties at high temperatures, thereby enhancing the heat resistance of the coating film. At the same time, the slightly acidic environment can also reduce the thermal decomposition or degradation reaction of PAA at high temperatures, avoiding the production of byproducts that are not conducive to heat resistance.

[0010] As a preferred implementation in this embodiment, 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 embodiment, the dispersant includes one or more of a nonionic surfactant or a polycarboxylate ammonium salt.

[0012] As a preferred implementation in this embodiment, 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 embodiment, 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 embodiment, 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 batteries for new energy vehicles includes the following steps:

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

[0017] S2. Preparing PAA slurry: adding a binder to a slurry mixing device loaded with acidic deionized water, adding a dispersant after a first mixing, adding a wetting agent after a second mixing, adding PAA after a third mixing, adding a thickener after a fourth mixing and grinding, and obtaining a PAA slurry after a 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, mixing and dispersing 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 a lithium battery composite diaphragm for new energy vehicles, comprising 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 tooth plate, and the tooth 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. 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 drive shaft arranged in the inner cavity of the mixing tank. A first spline shaft is arranged below the drive shaft, and the upper end of the first spline shaft is slidably arranged in the inner cavity of the drive 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 provided 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 provided 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 limiting rod is slidably provided in the inner cavity of the mounting block, and the upper end of the limiting 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 coupling unit is further provided for enabling the second gear to engage with the gear ring in advance for slurry mixing;

[0029] The gravity gear connection unit includes a second spline shaft, a gravity spring and two groups of tapered material receiving barrels that are wider at the top and narrower at the bottom. The upper end of the second spline shaft is slidably arranged in the inner cavity of the first spline shaft, and the second gear is fixed to the lower end of the second spline shaft. The gravity spring is fixed on the second gear, and the upper end of the gravity spring is rotatably connected to the rotating drum. A swivel is rotatably provided on the second gear, and two groups of mounting brackets are relatively provided on the swivel. The two groups of tapered material receiving barrels are respectively installed on the corresponding mounting brackets. 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 provided inside the tapered material receiving barrel, and the tapered material receiving barrels are both 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 further provided for controlling the automatic opening and closing of the discharge opening at the bottom of the tapered receiving barrel;

[0032] The automatic opening and closing unit includes a crossbar that slides transversely and passes through the mounting frame, a sealing plate is fixed to the right end of the crossbar, the crossbar is connected to the mounting frame via an opening and closing spring, a baffle is fixed to the left end of the crossbar, and a stopper is fixed to the left end of the baffle, and a guide slope is provided on the stopper;

[0033] Both side ends of the mounting plate are fixed with interference rods, and two groups of the interference rods are respectively adapted to be arranged with the corresponding stop blocks.

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

[0035] 1. The present invention has a reasonable structure. The ceramic slurry and PAA slurry are mixed in a certain proportion under acidic conditions to achieve one-time coating while improving the adhesion and heat resistance of the diaphragm.

[0036] 2. In the present invention, a set of servo motors is used to automatically switch and drive the stirring shaft that needs to be worked 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 motors, which shortens the motor's service life and increases energy consumption, and also avoids unnecessary trouble 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 following briefly introduces the drawings required for use in the embodiments or the description of the prior art. 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 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 A schematic diagram of the partially enlarged rear view structure;

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

[0046] Figure 7 for Figure 6 Enlarged structural diagram at point 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 clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts 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] 3.5 wt% binder was added to 83 wt% deionized water (acidic, pH = 5-5.5), 0.3 wt% dispersant was added after the first mixing, 0.2 wt% wetting agent was added after the second mixing, 6 wt% PAA was added after the third mixing, 7 wt% 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 9 μm PE base film, and then baked and rolled to obtain a 9+3 μm coated diaphragm.

[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] 3.5 wt% binder was added to 83 wt% deionized water (acidic, pH = 5-5.5), 0.3 wt% dispersant was added after the first mixing, 0.2 wt% wetting agent was added after the second mixing, 6 wt% PAA was added after the third mixing, 7 wt% 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 9 μm PE base film, and then baked and rolled to obtain a 9+3 μm coated diaphragm.

[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] 3.5 wt% binder was added to 83 wt% deionized water (acidic, pH = 5-5.5), 0.3 wt% dispersant was added after the first mixing, 0.2 wt% wetting agent was added after the second mixing, 6 wt% PAA was added after the third mixing, 7 wt% 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 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.

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

[0075] The prepared mixed slurry was coated on a 9 μm PE base film, and then baked and rolled to obtain a 9+3 μm coated diaphragm.

[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] 3.5 wt% binder was added to 83 wt% deionized water (acidic, pH = 5-5.5), 0.3 wt% dispersant was added after the first mixing, 0.2 wt% wetting agent was added after the second mixing, 6 wt% PAA was added after the third mixing, 7 wt% 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 9 μm PE base film, and then baked and rolled to obtain a 9+3 μm coated diaphragm.

[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. After the first mixing, 35wt% inorganic powder was added. After the second mixing and grinding, 4wt% binder was added. After the third mixing, 0.1wt% wetting agent was added. After the fourth mixing, 0.3wt% dispersant was added. After the fifth mixing, ceramic slurry was obtained. The obtained ceramic slurry was coated on a 9μm PE base film, baked and rolled to produce a 9+3μm coated separator.

[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.

[0092] Thermal 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 with reference to GB / T 27911995 standard.

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

[0095]

[0096] As can be seen from Table 1:

[0097] (1) The peel strengths of the coated membranes prepared using the ceramic and PAA mixed slurries in Examples 1-5 were all higher than the peel strength of the coated membrane prepared using the ceramic slurry in Comparative Example 1, indicating that a certain degree of mixing of the ceramic slurry and the PAA slurry helps to improve the peel strength of the coated membrane.

[0098] (2) The thermal shrinkage (TD and MD) of the coated membranes prepared using the ceramic and PAA mixed slurries in Examples 1-5 were all higher than that (TD and MD) of the coated membrane prepared using the ceramic slurry in Comparative Example 1. This indicates that a certain degree of mixing of the ceramic slurry and the PAA slurry helps improve the heat resistance of the coated membrane.

[0099] In summary, compared with the existing twice-coated diaphragms and ceramic-coated diaphragms, the ceramic and PAA mixed coating slurry prepared in this application not only has higher adhesion and heat resistance, but also can reduce the coating process, achieve one-time coating, and reduce costs. It 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 diaphragms 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 equipped 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 discharge pipes, and the discharge pipes are both provided with electric valves. The upper ends of the two first stirring shafts 4 are connected by a connecting rod 11, and a tooth plate 12 is fixed to the lower end of the connecting rod 11. The tooth plate 12 is gear-engaged 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 of the corresponding large mixing tank 1 and the two small mixing tanks 3. The discharge ends of the two groups of feeding funnels 6 are respectively located in the inner cavities of the corresponding 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 provided in the inner cavity of the mixing tank 1. A first spline shaft 21 is provided below the drive shaft 9, and the upper end of the first spline shaft 21 is slidably provided in the inner cavity of the drive shaft 9. The lower end of the first spline shaft 21 is fixedly installed with a second gear 18;

[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 the mounting plate 35;

[0104] A rotating drum 13 is rotatably mounted 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 provided 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 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 of the outer wall of the corresponding small mixing tank 3. A limiting rod 17 is slidingly 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;

[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 mixing tanks 3 and the mixing tank 1 through the liquid inlet pipe 5. During the adding process, due to the continuous increase in the overall weight of the mixing tank 3, the two 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 mixing tank 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 mixing tank 3 moves downward, it can drive the tooth plate 12 to move downward. The downward moving tooth plate 12 cooperates with the connecting tooth plate 14 to make the first spline shaft 21 drive the second gear 18 to move upward, and finally complete the plugging 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 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. 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 returns 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 is used to automatically switch and drive the stirring shaft that needs to work to rotate and stir without stopping the machine, reducing the number of motors used and reducing costs. It also avoids frequent starting and stopping of the motor to affect the motor's service life 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 coupling unit is also provided for enabling the second gear 18 to engage with the gear ring 19 in advance for slurry mixing;

[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, and the second gear 18 is fixed to the lower end of the second spline shaft 22. A 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 provided on the second gear 18, and two groups of mounting brackets 25 are relatively provided on the swivel 24. The two groups of tapered material receiving barrels 27 are respectively installed on the corresponding mounting brackets 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 provided inside the tapered material receiving barrel 27, and the tapered material receiving barrel 27 is opened at the top and bottom.

[0112] Two sets of columns 26 are fixed to the mounting plate 35, and the upper ends of the two columns 26 slide through the corresponding mounting brackets 25. When discharging the mixing tank 3, it takes a certain amount of time for the second gear 18 to plug into the gear ring 19. As a result, the two slurries cannot be mixed in advance during this period, which in turn prolongs the mixing time of the subsequent slurries. Therefore, a gravity plug-in unit is provided;

[0113] When the mixing tank 3 is discharging (at this time the second gear 18 is separated from the gear ring 19), the slurry discharged from its discharge pipe will fall into the conical receiving barrel 27, and the discharge volume of the opening unit time at the lower end of the conical receiving barrel 27 is less than the discharge volume of the discharge pipe unit time, thereby causing the slurry to accumulate in the conical receiving barrel 27, and 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 eventually 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 for controlling 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 crossbar 28 that slides transversely through the mounting frame 25. A sealing plate 29 is fixed to the right end of the crossbar 28. The crossbar 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 crossbar 28, and a stopper 31 is fixed to the left end of the baffle 30. A guide slope 34 is provided 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 stop blocks 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, which allows the second gear 18 to be quickly plugged into the gear ring 19. When the second gear 18 moves downward, The interference rod 32 will interfere with 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; setting an automatic opening and closing unit can 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 tapered receiving barrel 27 should not be too large, that is, the weight of the second gear 18 moving downward 1 to complete the gear engagement by relying on the tapered 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, those skilled in the art can still modify the technical solutions described in the aforementioned embodiments or 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 scope of protection of the present invention.

Claims

1. A slurry mixing device, used in the preparation process of lithium battery composite diaphragm for new energy vehicles, characterized by: The invention 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 provided 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 provided on both sides of the driving gear (10), and the driving gear (10) is gear-engaged with the two transmission gears (8); Both sides of the small mixing tank (3) are provided with mounting blocks (15), and the mounting blocks (15) are fixedly connected to the inner cavity wall of the large mixing tank (1); the upper end of the mounting block (15) is provided with a mounting hole, 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); the inner cavity of the mounting block (15) is slidably provided with a limiting rod (17), and the upper end of the limiting rod (17) is fixedly connected to the outer wall of the small mixing tank (3); At the beginning, 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).

2. A slurry mixing device according to claim 1, characterized in that: A gravity gear coupling unit is also provided for enabling the second gear (18) to engage with the gear ring (19) in advance to perform slurry mixing; The gravity tooth 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 on the second gear (18), and the upper end of the gravity spring (23) is rotatably connected to the rotating drum (13). A rotating ring (24) is rotatably provided on the second gear (18), and two groups of mounting brackets (25) are relatively arranged on the rotating ring (24). The two groups of tapered material receiving barrels (27) are respectively installed on the corresponding mounting brackets (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 provided inside the tapered material receiving barrel (27), and the tapered material receiving barrel (27) is opened at the top and 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).

3. A slurry mixing device according to claim 2, characterized in that: An automatic opening and closing unit is also provided for controlling 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) that slides transversely and passes through 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) via 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 provided on a protrusion of the stopper (31); Both side ends of the mounting plate (35) are fixed with a resistance rod (32), and two groups of the resistance rods (32) are respectively adapted to be arranged with the corresponding stop blocks (31).

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