Oil pumping and solvent drying system for preparing wet diaphragm of secondary battery

Abstract

The invention relates to an oil pumping and solvent drying system for preparing a wet diaphragm of a secondary battery. To this end, the system comprises: an oil pumping step in which a plurality of extraction tanks filled with a dichloromethane (MC) solvent are provided so that the MC solvent removes oil contained in the diaphragm passing through a plurality of rollers, and a spraying device for spraying the pure MC solvent onto the diaphragm passing through the rollers from the upper part of the extraction tanks is provided, the last extraction tank adjacent to the solvent drying process among the plurality of extraction tanks comprises a separation plate for dividing an internal space; and a solvent drying step in which a humidification unit, a first drying unit, a second drying unit, and a stabilization unit are provided.

Description

Technical Field

[0001] The invention relates to an oil extraction and solvent drying system for preparing a secondary battery wet diaphragm. Background Art

[0002] Generally, secondary batteries have high energy density and high operating voltage, as well as excellent storage and life characteristics, and are therefore widely used in various portable electronic devices such as personal computers, camcorders, mobile phones, portable CD players, and personal data assistants (PDAs).

[0003] Examples of secondary batteries include nickel-cadmium batteries, nickel-metal hydride batteries, and lithium batteries. Compared with other types of secondary batteries, lithium secondary batteries can be manufactured to have high energy density and long life, and thus are used in many fields.

[0004] The lithium secondary battery has a case filled with electrolyte and an electrode assembly housed in the case. The electrode assembly is composed of a positive electrode, a separator and a negative electrode stacked together to have a jelly-roll-shaped winding structure or a stack structure.

[0005] The above-mentioned lithium secondary battery diaphragm preparation process includes an extrusion process for preparing a diaphragm sheet, a casting process for crimping the diaphragm sheet, a first stretching process for the diaphragm sheet, an extraction process for removing oil formed in the pores of the diaphragm, and a second stretching process for maintaining the shape of the diaphragm.

[0006] In the above-mentioned lithium secondary battery separator production process, wrinkles may be generated in the separator during the extraction process due to the occurrence of undried parts, incomplete removal of oil, reduced drying performance, etc., and the oil or the MC (Methylene Chloride, dichloromethane) solvent for oil removal may not be completely removed.

[0007] A conventional lithium secondary battery separator extraction apparatus uses hot air and a heating roller simultaneously in order to remove the MC solvent used for extraction in the extraction process.

[0008] However, the existing lithium secondary battery diaphragm drying device has the following problem. When drying the diaphragm, if the MC solvent contained in the diaphragm is exposed to the outside, it will dry rapidly. As a result, the diaphragm will dry rapidly and wrinkle. As the surface of the diaphragm partially melts and shrinks, traces of evaporation of the MC solvent will be produced, resulting in a defective diaphragm.

[0009] Furthermore, when the hot air deviates to the left and right, the quality of the diaphragm will be reduced and the pore structure on the surface of the diaphragm will become uneven.

[0010] Furthermore, in the above-mentioned lithium secondary battery diaphragm production process, a plurality of extraction tanks are used in the extraction process. When the above-mentioned extraction tanks are filled with MC solvent, the diaphragm is put into the MC solvent to extract oil. In order to improve productivity, the production speed needs to be increased, but it is difficult to extract oil with the existing number of tanks, so increasing the number of tanks requires more equipment.

[0011] Prior art literature

[0012] Patent Literature

[0013] Patent Document 1: Korean Patent Gazette No. 10-1858566 (Invention Title: Secondary Battery Separator Preparation Method and Preparation Device, published on January 4, 2018)

[0014] Patent Document 2: Korean Patent Gazette No. 10-1561971 (Invention Title: System for Preparing Separator for Secondary Battery, published on April 14, 2015) Summary of the invention

[0015] The present invention has been proposed in view of the above-mentioned problems, and its object is to provide an oil extraction and solvent drying system for preparing a secondary battery wet diaphragm, which minimizes the contaminants of MC solvent generated in the extraction process of removing the oil contained in the diaphragm, and when the diaphragm is dried, moisture is applied to the inside of the drying chamber to suppress the occurrence of streaks and wrinkles on the diaphragm surface caused by the rapid drying of the MC solvent, thereby improving the quality of the diaphragm.

[0016] According to a preferred embodiment for achieving the above-mentioned purpose of the present invention, the oil extraction and solvent drying system for preparing a secondary battery wet diaphragm of the present invention may include: an oil extraction process, which is provided with a plurality of extraction tanks filled with MC solvent inside, so that the MC solvent removes the oil contained in the diaphragm passing through a plurality of rollers, and has a spraying device at the upper part of the above-mentioned extraction tank for spraying pure MC solvent to the diaphragm passing through the above-mentioned rollers; and a solvent drying process, which is provided with a humidifying section, a first drying section, a second drying section, and a stabilizing section, the above-mentioned humidifying section applies moisture to the inside of the humidifying tank arranged adjacent to the last extraction tank in the above-mentioned extraction tanks, the above-mentioned first drying section makes the diaphragm in the above-mentioned humidifying section pass through a plurality of heating rollers arranged inside a drying chamber and be dried, the above-mentioned second drying section makes the diaphragm dried in the above-mentioned first drying section pass through the heating rollers and be dried again, and the above-mentioned stabilizing section stabilizes the diaphragm of the next process arranged and transferred to the above-mentioned second drying section.

[0017] In the above-mentioned oil extraction process, pure MC solvent may be sprayed toward the diaphragm before the above-mentioned extraction tank is moved from the upper part of the water level of the MC solvent previously filled to the next extraction tank.

[0018] The pure MC solvent sprayed inside the above extraction tank may be sprayed through a solvent spray nozzle.

[0019] In the oil extraction process, the last extraction tank among the plurality of extraction tanks adjacent to the solvent drying process may include a separation plate that divides the inner space.

[0020] One side of the space divided by the separation plate can be used to supply the MC solvent, and the other side is maintained as an empty space for preliminary drying of the separator.

[0021] In the solvent drying step, the humidifying unit may be connected to an external humidifying device to apply moisture to the interior of the humidifying tank to maintain the interior of the humidifying tank in an excessively humid state.

[0022] The humidifying unit may include at least one air knife, and the at least one air knife is provided at a position adjacent to the internal heating roller and sprays air to remove the MC solvent attached to the separator.

[0023] According to the oil extraction and solvent drying system for preparing a secondary battery wet diaphragm of the present invention, in the extraction process of removing the oil contained in the diaphragm, an injection device for injecting pure MC solvent is provided, thereby minimizing the contamination of the MC solvent and reducing the production equipment and installation space set up for the extraction process, thereby economically producing the diaphragm.

[0024] Furthermore, when drying the separator, moisture is applied to the inside of the tank to suppress the occurrence of spots and wrinkles on the separator surface caused by rapid drying of the MC solvent, thereby improving the quality of the separator. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 1 is a diagram showing an oil extraction and solvent drying system for preparing a secondary battery wet diaphragm according to an embodiment of the present invention.

[0026] Figure 2 This is a diagram showing an oil extraction process for preparing a secondary battery wet separator according to an embodiment of the present invention.

[0027] Figure 3 This is a diagram showing a solvent drying process for preparing a secondary battery wet separator according to an embodiment of the present invention.

[0028] Description of Reference Numerals

[0029] 10: Extraction tank

[0030] 10A: Final extraction tank

[0031] 10B: Initial extraction tank

[0032] 10a: One side space

[0033] 10b: Other side space

[0034] 11: Roller

[0035] 12: Solvent spray nozzle

[0036] 13: Separation board

[0037] 20: Humidification part

[0038] 21: Humidifier tank

[0039] 22: Air Knife

[0040] 30: First drying section

[0041] 31: Drying chamber

[0042] 32: Heating roller

[0043] 40: Second drying section

[0044] 50: Stabilization Department

[0045] 60: Humidifier

[0046] 100: Oil extraction process

[0047] 200: Solvent drying process

[0048] F: Diaphragm

[0049] L: MC dissolving water level DETAILED DESCRIPTION

[0050] Hereinafter, with reference to the accompanying drawings, an embodiment of the oil extraction and solvent drying system for preparing a secondary battery wet diaphragm of the present invention is described. In this case, the present invention is not limited or restricted to the embodiment. In addition, in the process of describing the present invention, the specific description of the known functions or structures may be omitted in order to clarify the main purpose of the present invention.

[0051] Figure 1 1 is a diagram showing an oil extraction and solvent drying system for preparing a secondary battery wet diaphragm according to an embodiment of the present invention.

[0052] Reference Figure 1 The secondary battery diaphragm preparation system of the present invention includes an oil extraction process 100 for removing the oil contained in the diaphragm F and a solvent drying process 200 for drying the solvent attached to the diaphragm F. The productivity and quality of the diaphragm preparation can be improved through the above-mentioned oil extraction process 100 and solvent drying process 200.

[0053] In this embodiment, the oil extraction process 100 is provided with a plurality of extraction tanks 10 filled with MC solvent so that the MC solvent removes the oil contained in the diaphragm F passing through the plurality of rollers 11, and has an injection device at the upper part of the extraction tank 10 for injecting pure MC solvent toward the diaphragm F passing through the rollers 11.

[0054] That is, in the above-mentioned oil extraction process 100, a plurality of extraction tanks 10 are sequentially arranged so that the membrane F passes through the plurality of extraction tanks 10 by the rollers 11 and the oil contained in the membrane F is removed.

[0055] The above-mentioned injection device is arranged on the upper part of the extraction tank 10, and pure MC solvent is injected to the diaphragm F before moving to the next extraction tank 10, thereby improving the oil extraction effect, preventing the contaminated MC solvent attached to the diaphragm F from moving to the next extraction tank 10, and diluting the MC solvent inside the extraction tank 10, so that the oil can be extracted more efficiently.

[0056] The pure MC solvent is directly sprayed onto the diaphragm F by the spraying device to improve the oil extraction effect, thereby reducing the number or length of the extraction tanks 10.

[0057] Furthermore, the solvent drying process 200 includes: a humidifying section 20, which applies moisture to the interior of a humidifying tank 21 disposed adjacent to the last extraction tank 10A in the extraction tank 10; a primary drying section 30, which allows the diaphragm F of the humidifying section 20 to pass through a plurality of heating rollers 32 disposed inside a drying chamber 31 and be dried; a secondary drying section 40, which allows the diaphragm F dried in the primary drying section 30 to be dried again by passing through the heating rollers 32; and a stabilizing section 50, which stabilizes the diaphragm disposed and transferred to the next process of the secondary drying section 40.

[0058] That is, in the solvent drying step 200, the humidifying unit 20 supplies moisture to humidify the space of the humidifying unit 20, thereby preventing the MC solvent attached to the surface of the diaphragm F from increasing sharply during drying, thereby preventing the surface of the diaphragm F from having streaks or wrinkles generated during the preparation of the diaphragm.

[0059] Furthermore, the stabilizing unit 50 in the solvent drying step 200 stabilizes the separator F transferred from the secondary drying unit 40 , and the dry state of the surface of the separator F can be stabilized by the stabilizing unit 50 .

[0060] Therefore, the solvent drying process 200 supplies hot air to the separator F to humidify it, passes through the primary drying unit 30 to perform primary drying on the separator F, passes through the secondary drying unit 40 to perform secondary drying on the separator F, and passes through the stabilizing unit 50 to stabilize the separator F.

[0061] Figure 2 This is a diagram showing an oil extraction process for preparing a secondary battery wet separator according to an embodiment of the present invention.

[0062] Reference Figure 2In the above-mentioned oil extraction process 100 , the above-mentioned extraction tank 10 sprays pure MC solvent toward the diaphragm F above the pre-filled MC solution level L, and the pure MC solvent is sprayed through the solvent spray nozzle 12 .

[0063] That is, as described above, when pure MC solvent is sprayed from each extraction tank 10 to the membrane F through the solvent spray nozzle 12, the contaminated MC solvent attached to the membrane F is prevented from moving to the adjacent extraction tank 10, thereby increasing the oil extraction effect.

[0064] By maintaining the extraction tank 10 in a state where the contamination degree of the MC solvent is low, the number of extraction tanks 10, rollers 11, and various components can be reduced in the oil extraction process 100, and the installation space of the device can be reduced, thereby improving product productivity.

[0065] Furthermore, in the above-mentioned oil extraction process 100, the last extraction tank 10A adjacent to the above-mentioned solvent drying process 200 among the multiple extraction tanks 10 includes a separation plate 13 that divides the internal space. In the space divided by the above-mentioned separation plate 13, one side space 10a is used to supply MC solvent, and the other side space 10b can be maintained as an empty space for preliminary drying.

[0066] The separation plate 13 is provided in the final extraction tank 10A, and the rollers 11 are arranged so that the MC solvent flows naturally, thereby effectively removing the MC solvent in the oil extraction process 100, thereby reducing the length of the solvent drying process 200.

[0067] Figure 3 This is a diagram showing a solvent drying process for preparing a secondary battery wet separator according to an embodiment of the present invention.

[0068] Reference Figure 3 In the solvent drying step 200 , the humidifying unit 20 is connected to the external humidifying device 60 to apply moisture to the inside of the humidifying tank 21 , thereby maintaining the inside of the humidifying tank 21 in an excessively humid state.

[0069] Furthermore, the humidifying unit 20 includes at least one air knife 22 . The at least one air knife 22 is disposed adjacent to the internal heating roller and sprays air to remove the MC solvent attached to the separator F.

[0070] That is, in the humidifying unit 20, the air knife 22 supplies hot air to the separator F in a wet state to remove part of the MC solvent, and the remaining MC solvent is evaporated by the heating roller 32. Therefore, the generation of spots and wrinkles on the surface of the separator F can be suppressed by preventing rapid evaporation.

[0071] Therefore, in the oil extraction and solvent drying system for preparing a secondary battery wet diaphragm, in the extraction process of removing the oil contained in the diaphragm, an injection device for injecting pure MC solvent is provided, thereby minimizing the contamination of the MC solvent and reducing the production equipment and installation space set up for the extraction process, thereby economically producing the diaphragm.

[0072] Furthermore, when drying the separator, moisture is applied to the inside of the tank to suppress the formation of spots or wrinkles on the separator surface caused by rapid drying of the MC solvent, thereby improving the quality of the separator.

[0073] The present invention has been shown and described above in relation to the preferred embodiments for illustrating the principles of the present invention, and the present invention is not limited to the structures and functions shown and described above. On the contrary, a person skilled in the art of the art to which the present invention belongs may make various changes and modifications to the present invention without exceeding the concept and scope of the attached invention claims.

Claims

1. An oil extraction and solvent drying system for preparing a secondary battery wet diaphragm, characterized in that: include: The oil extraction process is provided with a plurality of extraction tanks filled with a dichloromethane solvent so that the dichloromethane solvent removes the oil contained in the membrane passing through the plurality of rollers, and a spraying device is provided at the upper part of the extraction tank to spray the pure dichloromethane solvent to the membrane passing through the rollers; and The solvent drying process is provided with a humidifying section, a primary drying section, a secondary drying section, and a stabilizing section. The humidifying section applies moisture to the interior of the humidifying tank arranged adjacent to the last extraction tank in the extraction tank. The primary drying section allows the diaphragm of the humidifying section to pass through a plurality of heating rollers arranged inside a drying chamber and be dried. The secondary drying section allows the diaphragm dried in the primary drying section to pass through heating rollers and be dried again. The stabilizing section stabilizes the diaphragm of the next process arranged and transferred to the secondary drying section.

2. The oil extraction and solvent drying system for preparing a secondary battery wet diaphragm according to claim 1, characterized in that: In the above oil extraction process, pure dichloromethane solvent is sprayed toward the diaphragm before the above extraction tank is moved from the upper part of the water level of the pre-filled dichloromethane solvent to the next extraction tank.

3. The oil extraction and solvent drying system for preparing a secondary battery wet diaphragm according to claim 2, characterized in that: The pure dichloromethane solvent sprayed inside the above extraction tank is sprayed through a solvent spray nozzle.

4. The oil extraction and solvent drying system for preparing a secondary battery wet diaphragm according to claim 1, characterized in that: In the above-mentioned oil extraction process, the last extraction tank among the plurality of extraction tanks adjacent to the above-mentioned solvent drying process includes a separation plate that divides the inner space.

5. The oil extraction and solvent drying system for preparing a secondary battery wet diaphragm according to claim 4, characterized in that: One side of the space divided by the separation plate is used to supply the dichloromethane solvent, and the other side is maintained as an empty space for preliminary drying of the separator.

6. The oil extraction and solvent drying system for preparing a secondary battery wet diaphragm according to claim 1, characterized in that: In the solvent drying step, the humidifying unit is connected to an external humidifying device to apply moisture to the interior of the humidifying tank, thereby maintaining the interior of the humidifying tank in an excessively humid state.

7. The oil extraction and solvent drying system for preparing a secondary battery wet diaphragm according to claim 6, characterized in that: The humidifying unit includes at least one air knife, which is disposed adjacent to the internal heating roller and sprays air to remove the dichloromethane solvent attached to the separator.

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