A lithium battery separator and method of making the same and a system for improving the morphology of a spray pattern

Abstract

This invention discloses a lithium battery separator, its preparation method, and a system for improving the morphology of sprayed dots. The method for improving the morphology of sprayed dots in a lithium battery separator includes the following steps: (1) returning excess sprayed slurry to an ultrasonic disperser via a return pipe, and using ultrasound to disperse the slurry; (2) sending the ultrasonically dispersed slurry to a filtration device for filtration, and storing the filtered slurry in a feeding tank; (3) sending the filtered slurry from the feeding tank into a feeding box, where a high-speed rotating rotor disk connected to the nozzle of the feeding box atomizes the sprayed slurry by high-speed shearing, and then spraying the atomized slurry onto the surface of the separator body. This invention solves the problem of slurry agglomeration by using ultrasonically dispersed and filtered slurry that has been sheared at high speed by a rotor disk, resulting in uniformly sized sprayed dots on the sprayed surface. This avoids the problem of low electrode adhesion caused by excessively small sprayed dots and reduces the proportion of large particles, thus preventing large particles from clogging the pores.

Description

Technical Field

[0001] This invention relates to a lithium battery separator, its preparation method, and a system for improving the morphology of sprayed points, belonging to the field of lithium battery separator coating technology. Background Technology

[0002] Slurry coating is a crucial step in the lithium-ion battery separator production process. The slurry in the cartridge is atomized by high-speed shearing in the spray head and then sprayed onto the surface of the lithium-ion battery separator. Excess slurry is recycled back into the cartridge via a return pipe. The aqueous PVDF return slurry, after high-shearing, is prone to agglomeration. When this agglomerated slurry is recycled, it easily forms spray dots of varying outer diameters on the membrane surface. Small spray dots do not provide adhesion to the separator and affect battery performance, while large spray dots can easily cause pore blockage.

[0003] Existing technologies improve the uniformity of spray dot morphology and size mainly by adjusting the parameters of the nozzle and the composition parameters of the slurry. However, these methods cannot fundamentally solve the technical problem of slurry agglomeration in the return flow. Summary of the Invention

[0004] The purpose of this invention is to provide a lithium battery separator. This invention also provides a method for preparing a lithium battery separator and an apparatus for improving the morphology of the spraying points of a sprayed separator for lithium batteries, in order to solve the shortcomings of existing lithium battery separators where the spraying slurry is prone to agglomeration and poor adhesion.

[0005] The lithium battery separator of the present invention adopts the following technical solution: a lithium battery separator, comprising a separator substrate and a PVDF coating coated on at least one side surface of the separator substrate, wherein the PVDF coating comprises spray dots, the spray dots are annular, the annular width of the spray dots is between 10-150 μm, the thickness of the spray dots is between 0.5-15 μm, and the number of spray dots with an outer diameter between 200-500 μm is more than 90% of the total number of spray dots.

[0006] The ring width of the sprayed dots is between 20-90 μm, and the thickness of the sprayed dots is between 0.8-6 μm.

[0007] The number of sprays with a single outer diameter between 100-200μm is less than 4% of the total number of spray points, and the number of sprays with a single outer diameter between 500-800μm is less than 6% of the total number of spray points.

[0008] The preparation method of the lithium battery separator of the present invention adopts the following technical solution: A preparation method of lithium battery separator, comprising the following steps: (1) mixing PVDF resin, thickener, binder, water and dispersant evenly to obtain PVDF slurry; (2) spraying the PVDF slurry onto the surface of at least one side of the separator substrate by spraying to obtain a PVDF coating containing annular spray dots, wherein the ring width of the spray dots is between 10-150 μm, the thickness of the spray dots is between 0.5-15 μm, and the number of spray dots with an outer diameter between 200-500 μm is... More than 90% of the total number of spray points; (3) Dry the membrane substrate with spray points to obtain a lithium battery separator; Step (2) also includes the following steps: A. Return the excess slurry sprayed through the return pipe to the ultrasonic disperser and use ultrasonic waves to disperse the slurry; B. Send the ultrasonically dispersed slurry to the filter device for filtration and store the filtered slurry in the feeding tank; C. Send the filtered slurry in the feeding tank to the material box. When the rotor disk connected to the nozzle of the material box rotates at high speed, it performs high-speed shearing on the slurry to atomize the slurry. After atomization, the slurry is sprayed onto the surface of the base membrane.

[0009] In step A, the flow rate of the slurry entering the ultrasonic disperser is 500-1500 ml / s, the ultrasonic dispersion temperature is 18-25℃, the power of the ultrasonic disperser is 1000W-3000W, and the frequency of the ultrasonic disperser is 18-50HZ.

[0010] The filtration in step B is a graded filtration with three filtration stages. The mesh size of each stage is between 40 and 150 mesh, and the mesh size gradually increases along the direction of slurry flow.

[0011] In step C, the flow rate of the slurry in the nozzle of the spray head is 400-1500 ml / s, and the rotation speed of the rotor disc is 5000-15000 rpm.

[0012] The system for improving the morphology of sprayed dots on a lithium battery separator according to the present invention adopts the following technical solution: A system for improving the morphology of sprayed dots on a lithium battery separator includes a material box, a spraying head connected to the material box, a feeding pipe and a return pipe connected to the material box, a rotor turntable provided on the spraying head, an ultrasonic disperser and a filter provided between the return pipe and the feeding pipe, an inlet pipe and an outlet pipe provided on the ultrasonic disperser, the inlet pipe connected to the return pipe, the outlet pipe connected to the filter inlet, a filter screen provided inside the filter, and a feeding tank for storing the filtered slurry connected to the filter outlet, the feeding tank being connected to the feeding pipe.

[0013] The slurry flow rate in the feed pipe of the ultrasonic disperser is 500-1500 ml / s, the working temperature inside the ultrasonic disperser is 18-25℃, the power of the ultrasonic disperser is 1000W-3000W, and the frequency of the ultrasonic disperser is 18-50HZ.

[0014] There are three filters connected in series. The mesh size of the filter screen in each stage is between 40 and 150 mesh, and the mesh size of the filter screen gradually increases along the direction of slurry flow.

[0015] The flow rate of the slurry in the spray nozzle of the spray head is 400-1500ml / s, and the rotation speed of the rotor disc is 5000-15000rpm.

[0016] The beneficial effects of this invention are as follows: This invention uses ultrasound to ultrasonically disperse the reflux slurry, refining the organic and inorganic particles in the slurry, improving the dispersion degree, and reducing slurry agglomeration. Then, the ultrasonically dispersed slurry is filtered to further remove large particles, ensuring no large particle agglomeration and better dispersion. After ultrasonic dispersion and filtration, the slurry undergoes high-speed shearing by a rotor disc, solving the problem of slurry agglomeration and resulting in uniform spray dots on the coating surface. This avoids the problem of low electrode adhesion due to excessively small spray dots, thus preventing the battery from being too soft to fit into the casing; simultaneously, it reduces the proportion of large particles, preventing large particles from clogging pores. The separator prepared by this invention has a better rate capability and can be applied to power batteries and high-rate consumer electronics batteries. Therefore, this invention improves the uniformity of spray dot size and enhances the adhesion strength of the sprayed separator.

[0017] Preferably, a three-stage filtration process is used to achieve better dispersion and refinement of the slurry after filtration. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the system for improving the morphology of sprayed coating points in a sprayed separator for lithium batteries according to the present invention; Figure 2 yes Figure 1 Schematic diagram of the structure of the central rotor turntable; Figure 3 This is a data table of spray points in the diaphragms prepared in Examples 1-5 and Comparative Example 1; Figure 4 This is a 5x magnified photograph of the diaphragm prepared in Example 2; Figure 5 This is a 1.5x magnified photograph of the diaphragm prepared in Example 2.

[0019] In the diagram: 1-Spraying head, 2-Return pipe, 3-Ultrasonic disperser, 4-Feed pipe, 5-Discharge pipe, 6-Filter, 7-Feeding tank, 8-Feeding pipe, 9-Rotor turntable, 91-Rotating shaft, 92-Upper dispersion disc, 93-Lower dispersion disc. Detailed Implementation

[0020] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments.

[0021] A specific embodiment of the lithium battery separator of the present invention: The lithium battery separator of this embodiment includes a separator substrate and a PVDF coating coated on at least one surface of the separator substrate. The PVDF coating includes spray dots, which are annular in shape. The annular width of the spray dots is between 10-150 μm, and the thickness of the spray dots is between 0.5-15 μm. The number of spray dots with an outer diameter of 200-500 μm is more than 90% of the total number of spray dots. Preferably, the annular width of the spray dots is between 20-90 μm, and the thickness of the spray dots is between 0.8-6 μm. Preferably, the number of spray dots with an outer diameter of 100-200 μm is less than 4% of the total number of spray dots, and the number of spray dots with an outer diameter of 500-800 μm is less than 6% of the total number of spray dots.

[0022] A specific embodiment of the method for preparing the lithium battery separator of the present invention: The method for preparing the lithium battery separator in this embodiment includes the following steps: (1) mixing PVDF resin, thickener, binder, water and dispersant evenly to obtain PVDF slurry.

[0023] (2) The PVDF slurry is sprayed onto the surface of at least one side of the diaphragm substrate by spraying to obtain a PVDF coating containing annular spray dots. The ring width of the spray dots is between 10-150 μm, the thickness of the spray dots is between 0.5-15 μm, and the number of spray dots with an outer diameter between 200-500 μm is more than 90% of the total number of spray dots.

[0024] This step also includes the following steps: A. Returning excess sprayed slurry to the ultrasonic disperser through a return pipe, and using ultrasound to disperse the slurry; in this step, the slurry flow rate entering the ultrasonic disperser is 500-1500 ml / s, the ultrasonic dispersion temperature is 18-25℃, the power of the ultrasonic disperser is 1000W-3000W, and the frequency of the ultrasonic disperser is 18-50HZ. B. The ultrasonically dispersed slurry is fed into a filtration device for filtration, and the filtered slurry is stored in a feeding tank. The filtration is a three-stage filtration, with each stage having a mesh size between 40 and 150 mesh. The mesh size gradually increases along the slurry flow direction. C. The filtered slurry in the feeding tank is fed into a material box. When the rotor disk connected to the nozzle of the material box rotates at high speed, it performs high-speed shearing on the slurry to atomize it. The atomized slurry is sprayed onto the surface of the base film. The flow rate of the slurry in the nozzle of the spray head is 400-1500 ml / s, and the rotation speed of the rotor disk is 5000-15000 rpm.

[0025] (3) The membrane substrate with spray dots is dried to obtain a lithium battery separator.

[0026] like Figure 1 As shown, this embodiment describes a system for improving the morphology of sprayed coating points on a lithium battery separator. The system includes a material box, a spray head 1 connected to the material box, a feeding pipe 8 and a return pipe 2 connected to the material box, a rotor 9 on the spray head 1, an ultrasonic disperser 3 and a filter 6 between the return pipe 2 and the feeding pipe 8, an inlet pipe 4 and an outlet pipe 5 on the ultrasonic disperser 3, the inlet pipe 4 connected to the return pipe 2, the outlet pipe 5 connected to the inlet of the filter 6, a filter screen inside the filter 6, and a feeding tank 7 connected to the outlet of the filter 6 for storing the filtered slurry. The feeding tank 7 is connected to the feeding pipe.

[0027] The structure of rotor disk 9 is as follows Figure 2 As shown, it includes a rotating shaft 91, an upper dispersing disk 92 and a lower dispersing disk 93 mounted on the rotating shaft 91, the upper dispersing disk 92 and the lower dispersing disk 93 are spaced apart, and the upper surface of the lower dispersing disk 93 has a texture.

[0028] The slurry flow rate in the feed pipe 4 of the ultrasonic disperser 3 is 500-1500 ml / s, the working temperature inside the ultrasonic disperser 3 is 18-25℃, the power of the ultrasonic disperser 3 is 1000W-3000W, and the frequency of the ultrasonic disperser 3 is 18-50HZ.

[0029] In this embodiment, there are three filters 6 connected in series. The mesh size of the filter screen in each stage is between 40 and 150 mesh, and the mesh size of the filter screen gradually increases along the direction of slurry flow.

[0030] The flow rate of the slurry in the nozzle of the spray head 1 is 400-1500ml / s, and the rotation speed of the rotor disc 9 is 5000-15000rpm.

[0031] The slurry used in this invention is prepared by the following steps: (1) Mix the binder with water and stir to form a homogeneous solution to obtain solution A; (2) Add small amounts of organic polymer to solution A in batches under stirring to obtain slurry B; (3) Grind slurry B through a grinding process to obtain slurry C; (4) Add binder to slurry C and mix evenly to obtain the finished slurry.

[0032] In this embodiment, the system for improving the morphology of sprayed dots on lithium battery separators is used by placing the finished slurry into a hopper and spraying it onto the separator substrate using a spray head. The slurry is atomized under the high-speed shearing action of the rotor disc, resulting in a uniform coating on the separator substrate. Excess slurry is collected in a trough below the spray head and then flows through a return pipe into an ultrasonic disperser. Under the oscillation of the ultrasonic waves, agglomerated organic and inorganic particles in the slurry are dispersed and refined, improving the dispersion degree. The ultrasonically dispersed slurry then enters a filter to remove large particles. This embodiment employs a three-stage filtration process, with each stage progressively increasing precision. After three stages of filtration, no large particles agglomerate in the slurry, resulting in better dispersion. The filtered slurry is stored in a feeding tank and then transported to the spray head through a feeding pipe. Under the high-speed shearing action of the rotor disc, the slurry is atomized and uniformly coated onto the separator substrate, ultimately forming a separator product with uniformly sized and shaped sprayed dots.

[0033] The present invention will be specifically described below with reference to specific examples: Example 1: (1) Ultrasonic dispersion of reflux material: The PVDF reflux material generated after spraying is fed into the ultrasonic disperser through the slurry reflux pipe 2. The ultrasonic disperser is set to a slurry flow rate of 600ml / s, a working power of 1500W, and a frequency of 20HZ for ultrasonic dispersion to improve the uniformity of slurry dispersion.

[0034] (2) Slurry filtration treatment after ultrasonic dispersion: The improved slurry is graded and filtered along the direction of slurry flow, with filtration mesh sizes of 40 mesh, 80 mesh and 100 mesh, respectively, to filter the agglomerated components in the slurry.

[0035] (3) Coating of PVDF slurry: The improved PVDF slurry was coated on both sides of the base film by high-speed rotary spraying. The coating speed was 50 m / min and the rotation speed of the rotary nozzle was 10,000 rpm / min. After drying, the sprayed membrane was obtained.

[0036] The morphology of the sprayed dots was measured using a high-definition CCD measuring microscope. The outer and inner diameters of the annular sprayed dots were measured using the scale on the microscope. The ring width was calculated based on the measured outer and inner diameter values. Half of the difference between the outer and inner diameter values ​​was the ring width of the sprayed dots. The average thickness of the sprayed dots was measured using a Maer thickness gauge. Before spraying, the average thickness of the diaphragm substrate was measured, and then the average thickness of the diaphragm with the sprayed dots was measured. The difference between the average thickness of the diaphragm and the average thickness of the diaphragm substrate was the average thickness of the sprayed dots.

[0037] Example 2: (1) Ultrasonic dispersion of reflux material: The PVDF reflux material generated after spraying is fed into the ultrasonic disperser through the slurry reflux pipe 2. The ultrasonic disperser is set to a slurry flow rate of 900ml / s, a working power of 2000W, and a frequency of 30HZ for ultrasonic dispersion to improve the uniformity of slurry dispersion.

[0038] (2) Slurry filtration treatment after ultrasonic dispersion: The improved slurry is graded and filtered along the direction of slurry flow, with filtration mesh sizes of 40 mesh, 80 mesh and 100 mesh, respectively, to filter the agglomerated components in the slurry.

[0039] (3) Coating of PVDF slurry: The improved PVDF slurry was coated on both sides of the base ceramic membrane by high-speed rotary spraying. The coating speed was 80 m / min, the rotation speed of the rotary nozzle was 7000 rpm / min, and the flow rate was 850 ml / s. After drying, the sprayed membrane was obtained.

[0040] The morphology of the sprayed points was measured using a high-definition CCD measuring microscope, and the average thickness of the sprayed points was measured using a Marl thickness gauge. The measurement method was the same as in Example 1. Figure 4 This is a 5x magnified photograph of the diaphragm prepared in this example, taken using a high-resolution CCD measuring microscope. Figure 5 This is a 1.5x magnified photograph of the diaphragm prepared in this example, taken using a high-definition CCD measuring microscope.

[0041] Example 3: (1) Ultrasonic dispersion of reflux material: The PVDF reflux material generated after spraying is fed into the ultrasonic disperser through the slurry reflux pipe 2. The ultrasonic disperser is set to a slurry flow rate of 1200ml / s, a working power of 2500W, and a frequency of 35HZ for ultrasonic dispersion to improve the uniformity of slurry dispersion.

[0042] (2) Slurry filtration treatment after ultrasonic dispersion: The improved slurry is graded and filtered along the direction of slurry flow, with filtration mesh sizes of 40 mesh, 80 mesh and 100 mesh, respectively, to filter the agglomerated components in the slurry.

[0043] (3) Coating of PVDF slurry: The improved PVDF slurry was coated on both sides of the base film by high-speed rotary spraying. The coating speed was 90 m / min, the rotation speed of the rotary nozzle was 8000 rpm / min, and the flow rate was 800 ml / s. After drying, the sprayed membrane was obtained.

[0044] The morphology of the sprayed points was measured using a high-definition CCD measuring microscope, and the average thickness of the sprayed points was measured using a Marl thickness gauge. The measurement method was the same as in Example 1.

[0045] Example 4: (1) Ultrasonic dispersion of reflux material: The PVDF reflux material generated after spraying is fed into the ultrasonic disperser through the slurry reflux pipe 2. The ultrasonic disperser is set to a slurry flow rate of 1500ml / s, a working power of 3000W, and a frequency of 40HZ for ultrasonic dispersion to improve the uniformity of slurry dispersion.

[0046] (2) Slurry filtration treatment after ultrasonic dispersion: The improved slurry is graded and filtered along the direction of slurry flow, with filtration mesh sizes of 40 mesh, 80 mesh and 100 mesh, respectively, to filter the agglomerated components in the slurry.

[0047] (3) Coating of PVDF slurry: The improved PVDF slurry was coated on both sides of the base film by high-speed rotary spraying. The coating speed was 100 m / min, the rotation speed of the rotary nozzle was 6000 rpm / min, and the flow rate was 700 ml / s. After drying, the sprayed membrane was obtained.

[0048] The morphology of the sprayed points was measured using a high-definition CCD measuring microscope, and the average thickness of the sprayed points was measured using a Marl thickness gauge. The measurement method was the same as in Example 1.

[0049] Example 5: (1) Ultrasonic dispersion of reflux material: The PVDF reflux material generated after spraying is fed into the ultrasonic disperser through the slurry reflux pipe 2. The ultrasonic disperser is set to a slurry flow rate of 1500ml / s, a working power of 3000W, and a frequency of 40HZ for ultrasonic dispersion to improve the uniformity of slurry dispersion.

[0050] (2) Slurry filtration treatment after ultrasonic dispersion: The improved slurry is graded and filtered along the direction of slurry flow, with filtration mesh sizes of 80 mesh, 100 mesh and 150 mesh, respectively, to filter the agglomerated components in the slurry.

[0051] (3) Coating of PVDF slurry: The improved PVDF slurry was coated on both sides of the ceramic membrane by high-speed rotary spraying. The coating speed was 50 m / min, the rotation speed of the rotary nozzle was 6000 rpm / min, and the flow rate was 700 ml / s. After drying, the sprayed membrane was obtained.

[0052] The morphology of the sprayed points was measured using a high-definition CCD measuring microscope, and the average thickness of the sprayed points was measured using a Marl thickness gauge. The measurement method was the same as in Example 1.

[0053] Comparative Example 1: The reflux material was directly fed into the feed tank, and then the PVDF slurry was coated on both sides of the ceramic by high-speed rotary spraying. The coating speed was 100m / min, the rotation speed of the rotary nozzle was 6000rpm / min, and the flow rate was 700ml / s. After drying, the sprayed diaphragm was obtained.

[0054] The morphology of the sprayed points was measured using a high-definition CCD measuring microscope, and the average thickness of the sprayed points was measured using a Marl thickness gauge. The measurement method was the same as in Example 1.

[0055] The parameters of the spraying points of the sprayed diaphragms prepared in Examples 1-5 and Comparative Example 1 are compared as follows: Figure 3 As shown in the table, the data in the table shows that in the diaphragm prepared according to the present invention, the number of spray points with an outer diameter between 200-500 μm is more than 90% of the total number of spray points, the number of spray points with an outer diameter between 100-200 μm is less than 4% of the total number of spray points, and the number of individual spray points with an outer diameter between 500-800 μm is less than 6% of the total number of spray points; while in Comparative Example 1, the number of spray points with an outer diameter between 200-500 μm is less than 90% of the total number of spray points. Compared with the products prepared in Comparative Examples 1-5, the PVDF coating product with untreated reflow slurry has an uneven morphology distribution of spray points.

[0056] The foregoing has shown and described the basic principles and main features of the present invention. Obviously, the present invention is not limited to the above embodiments, and many variations are possible. All variations that can be directly derived or conceived by those skilled in the art from the disclosure of the present invention should be considered within the scope of protection of the present invention.

Claims

1. A method for producing a lithium battery separator, characterized by, It includes the following steps: (1) Mix PVDF resin, thickener, binder, water and dispersant evenly to obtain PVDF slurry; (2) Spray the PVDF slurry onto the surface of at least one side of the diaphragm substrate by spraying to obtain a PVDF coating containing annular spray dots, wherein the ring width of the spray dots is between 10-150 μm, the thickness of the spray dots is between 0.5-15 μm, and the number of spray dots with an outer diameter between 200-500 μm is more than 90% of the total number of spray dots; (3) The PVDF slurry with spray dots is then applied to the diaphragm substrate. The membrane substrate is dried to obtain a lithium battery separator; step (2) further includes the following steps: A. The excess slurry sprayed is returned to the ultrasonic disperser through the return pipe, and the slurry is ultrasonically dispersed by ultrasonic waves; B. The ultrasonically dispersed slurry is sent to the filter device for filtration, and the filtered slurry is stored in the feeding tank; C. The filtered slurry in the feeding tank is sent to the material box, and the rotor disk connected to the nozzle of the material box rotates at high speed to perform high-speed shearing of the slurry and atomize the slurry. After atomization, the slurry is sprayed onto the surface of the base membrane.

2. The method of claim 1, wherein: In step A, the flow rate of the slurry entering the ultrasonic disperser is 500-1500 ml / s, the ultrasonic dispersion temperature is 18-25℃, the power of the ultrasonic disperser is 1000W-3000W, and the frequency of the ultrasonic disperser is 18-50HZ.

3. The method of claim 1, wherein: The filtration in step B is a graded filtration with three filtration stages. The mesh size of each stage is between 40 and 150 mesh, and the mesh size gradually increases along the direction of slurry flow.

4. The method of claim 1, wherein: In step C, the flow rate of the slurry in the nozzle of the spray head is 400-1500 ml / s, and the rotation speed of the rotor disc is 5000-15000 rpm.

5. The method of claim 1, wherein: The ring width of the sprayed dots is between 20-90 μm, and the thickness of the sprayed dots is between 0.8-6 μm.

6. The method of claim 1, wherein: The number of sprays with a single outer diameter between 100-200μm is less than 4% of the total number of spray points, and the number of sprays with a single outer diameter between 500-800μm is less than 6% of the total number of spray points.

7. A system for improving the spray dot morphology of a spray coated separator for a lithium battery, which is used to perform the method for preparing a lithium battery separator according to any one of claims 1-6, the system for improving the spray dot morphology of a spray coated separator for a lithium battery comprising a hopper, a spray head connected to the hopper, a feed conduit connected to the hopper, and a return conduit connected to the hopper, characterized in that: The spraying machine head is equipped with a rotor turntable. An ultrasonic disperser and a filter are provided between the return pipe and the feeding pipe. The ultrasonic disperser is equipped with a feed pipe and a discharge pipe. The feed pipe is connected to the return pipe, and the discharge pipe is connected to the filter inlet. The filter is equipped with a filter screen. The filter outlet is connected to a feeding tank for storing the filtered slurry. The feeding tank is connected to the feeding pipe.

8. The system for improving the spray spot morphology of a spray coated separator for lithium batteries of claim 7, wherein: The slurry flow rate in the feed pipe of the ultrasonic disperser is 500-1500 ml / s, the working temperature inside the ultrasonic disperser is 18-25℃, the power of the ultrasonic disperser is 1000W-3000W, and the frequency of the ultrasonic disperser is 18-50HZ.

9. The system for improving the spray spot morphology of a spray coated separator for lithium batteries of claim 7, wherein: There are three filters connected in series. The mesh size of the filter screen in each stage is between 40 and 150 mesh, and the mesh size of the filter screen gradually increases along the direction of slurry flow.

10. The system for improving the spray spot morphology of a spray coated separator for lithium batteries of claim 7, wherein: The flow rate of the slurry in the spray nozzle of the spray head is 400-1500ml / s, and the rotation speed of the rotor disc is 5000-15000rpm.

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