Drying system for manufacturing secondary battery separator

Abstract

The present invention relates to a drying system for preparing a separator of a secondary battery, which can maintain a dry state of a surface of a separator film well in a drying process of the separator film. To this end, the drying system for preparing a separator of a secondary battery includes an anti-icing part which, after an extraction process, warms up a plurality of preheating rollers arranged inside a preheating chamber to prevent icing of a surface of a separator film; a pretreatment part which, using pinch rollers, pinches both end portions of the separator film drawn from the anti-icing part to unroll the separator film before entering a drying chamber; a primary drying part which, again dries the separator film warmed up in the anti-icing part as it passes through a plurality of heating rollers; and a secondary drying part which, again dries the separator film dried in the primary drying part.

Description

Technical Field

[0001] This invention relates to a drying system for preparing separation membranes for secondary batteries. Background Technology

[0002] Generally, rechargeable batteries have many advantages, including high energy density, high starting voltage, and excellent shelf life characteristics, and are widely used in various portable electronic devices such as personal computers, portable video cameras, portable telephones, portable CD players, and handheld computers (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 with high energy density and long lifespan, and are used in a variety of fields.

[0004] The aforementioned lithium secondary battery has a case filled with electrolyte and an electrode assembly housed inside the case. The electrode assembly is composed of an anode, a separator, and a cathode stacked together, and has a jelly-roll-like or stacked structure.

[0005] The preparation process of the separation membrane film of the above-mentioned lithium secondary battery includes: an extrusion process for preparing a separation membrane sheet; a casting process for pressing the separation membrane sheet; a first stretching process for the separation membrane sheet; an extraction process for removing oil from the pores formed in the separation membrane film; and a second stretching process for maintaining the shape of the separation membrane film.

[0006] In the production process of the lithium secondary battery separator membrane, wrinkles may occur on the separator membrane due to the generation of undried parts in the extraction process, incomplete removal of oil, low drying performance, etc., which may prevent the complete removal of oil or the MC solvent used for oil removal.

[0007] In order to ensure the airtightness of the harmful gas MC (methyl-chloride) solvent gas generated in the extraction process, the existing lithium secondary battery separator membrane drying device adopts a water shower system. During the drying process, hot air and heated rollers are used simultaneously to dry the MC solvent and water.

[0008] However, existing lithium secondary battery separator film drying equipment has difficulty controlling the temperature of hot air and heating rollers when drying the separator film. As a result, the surface of the separator film melts and shrinks locally, causing wrinkles in the separator film and resulting in a defective separator film.

[0009] Existing technical documents

[0010] Patent documents

[0011] Patent Document 1: Korean Patent Publication No. 10-1858566 (Invention Title: Method and Apparatus for Preparing Separation Membrane for Secondary Batteries, published on January 4, 2018)

[0012] Patent Document 2: Korean Patent Publication No. 10-1561971 (Invention Title: Preparation System for Separation Membrane Thin Film for Secondary Batteries, Published April 14, 2015) Summary of the Invention

[0013] The present invention is proposed to solve the above-mentioned problems. The purpose of the present invention is to provide a drying system for preparing a secondary battery separator membrane, that is, to more effectively remove the MC solvent remaining on the surface of the separator membrane during the drying process of the separator membrane, while maintaining the dry state of the separator membrane surface.

[0014] According to a preferred embodiment for achieving the above-described object of the present invention, the drying system for preparing a secondary battery separator membrane of the present invention may include: an anti-icing section, which, after the extraction process, heats a plurality of preheating rollers disposed inside a preheating chamber to prevent icing on the surface of the separator membrane; a pretreatment section, which uses clamping rollers to hold both ends of the separator membrane drawn out from the anti-icing section and unfolds the separator membrane before it enters the drying chamber; a primary drying section, which maintains the temperature of a plurality of heating rollers disposed inside the drying chamber in the range of 40°C to 60°C, so that the separator membrane heated in the anti-icing section is dried again when passing through the heating rollers; and a secondary drying section, which maintains the temperature of the heating rollers in the range of 50°C to 80°C, so that the separator membrane dried in the primary drying section is dried again.

[0015] The aforementioned anti-icing section can supply hot air to the surface of the separation membrane and humidify it through an air knife arranged adjacent to the aforementioned preheating roller.

[0016] The present invention may further include a stabilization process unit, which includes: a primary stabilization unit, which uses a clamping roller disposed between the primary drying unit and the secondary drying unit to stabilize the transferred separation membrane film; and a secondary stabilization unit, disposed at a subsequent process position of the secondary drying unit, to stabilize the transferred separation membrane film.

[0017] The heating roller has multiple spiral heat medium circulation pipes formed on its inner side along the circumferential surface. Along the heat medium circulation pipes, heat medium can be supplied or discharged from one side to the other or from the other side to one side in the axial direction of the heating roller.

[0018] The present invention may further include a tension control unit disposed outside the secondary stabilization section to adjust the tension of the separation membrane film transferred to the next process.

[0019] The aforementioned tension control unit may include a pair of tension rollers that contact the separation membrane film and adjust the tension of the separation membrane film by adjusting their positions.

[0020] The drying system for preparing a secondary battery separator according to the present invention can more effectively recover the MC solvent remaining on the surface of the separator membrane during the drying process, and can ensure a good drying state of the separator membrane surface by maintaining a stable environment in the drying chamber.

[0021] Furthermore, the temperature control of the heating roller can be made easier by using a heat medium that circulates more effectively. In this way, the appropriate temperature is provided to the separation membrane film, thereby preventing wrinkles from forming on the surface of the separation membrane film due to melting shrinkage caused by localized high-temperature hot air. Attached Figure Description

[0022] Figure 1 A diagram illustrating a drying system for preparing a secondary battery separation membrane according to an embodiment of the present invention.

[0023] Figure 2 The diagram illustrates the anti-icing section and the primary drying section of a drying system according to an embodiment of the present invention.

[0024] Figure 3 The diagram illustrates the secondary drying section and the stabilization process section of a drying system according to an embodiment of the present invention.

[0025] Figure 4 A diagram illustrating the heating roller of a drying system according to an embodiment of the present invention.

[0026] Figure 5 A diagram illustrating the internal structure of a heating roller according to an embodiment of the present invention.

[0027] Figure 6 A diagram illustrating the heat medium circulation state of a heating roller according to an embodiment of the present invention.

[0028] Figure 7 A diagram illustrating the tension control unit of a drying system according to an embodiment of the present invention.

[0029] Figure 8 This diagram illustrates the operating state of the tension control unit according to an embodiment of the present invention.

[0030] Explanation of reference numerals in the attached figures

[0031] 1: Drying system 2: Heating roller

[0032] 2a: Heat medium circulation pipe; 2b: Inlet.

[0033] 2c: Outlet 10: Anti-icing section

[0034] 11: Preheating chamber; 12: Preheating roller

[0035] 13: Air knife; 20: Pretreatment section

[0036] 21: Pinch rollers; 30: Primary drying section

[0037] 31: Drying chamber; 40: Secondary drying section

[0038] 41: Drying chamber; 50: Stabilization process section

[0039] 51: Primary stabilization section; 51a: Pinch roller.

[0040] 52: Secondary stabilization section; 52a: Roller

[0041] 60: Tension control unit; 61: Tension roller

[0042] 61a: Rotating shaft; 62: Connecting component

[0043] 63: Servo motor

[0044] F: Separation membrane thin film Detailed Implementation

[0045] Hereinafter, an embodiment of the drying system for preparing a secondary battery separator according to the present invention will be described with reference to the accompanying drawings. However, the present invention is not limited to or confined to this embodiment. Furthermore, in order to clarify the essence of the invention, descriptions of well-known functions or structures will be omitted.

[0046] Figure 1 A diagram illustrating a drying system for preparing a secondary battery separation membrane according to an embodiment of the present invention is provided. Figure 2 The diagram illustrates the anti-icing section and the primary drying section of a drying system according to an embodiment of the present invention. Figure 3 The diagram illustrates the secondary drying section and the stabilization process section of a drying system according to an embodiment of the present invention.

[0047] Reference Figures 1 to 3 The drying system 1 for preparing a secondary battery separator membrane of the present invention includes an anti-icing section 10, a pretreatment section 20, a primary drying section 30 and a secondary drying section 40, which can remove the MC solvent of the separator membrane F while passing the separator membrane F through the anti-icing section 10, the pretreatment section 20, the primary drying section 30 and the secondary drying section 40 in sequence.

[0048] In this embodiment, the anti-icing section 10 of the drying system 1 prevents icing on the surface of the separation membrane film F by heating the plurality of preheating rollers 12 disposed inside the preheating chamber 11 after the extraction process. If the separation membrane film F is exposed with MC solvent adhering to its surface, the probability of breakage of the separation membrane film F will increase due to icing. Therefore, the anti-icing section 10 is provided to prevent this phenomenon. The anti-icing section 10 prevents the preheating rollers 12 from freezing.

[0049] The aforementioned anti-icing section 10 supplies hot air to the surface of the separation membrane film F through an air knife 13 arranged adjacent to the preheating roller 12 and humidifies it, using the hot air from the air knife 13 to shake the separation membrane film F.

[0050] The pretreatment section 20 uses clamping rollers 21 to hold both ends of the separation membrane film F drawn out from the anti-icing section 10, and unfolds the separation membrane film F before it enters the drying chamber 31. This is a pretreatment process to dry the separation membrane film F more effectively by fully unfolding it before placing it into the primary drying section 30.

[0051] The aforementioned primary drying section 30 maintains the temperature of the heating rollers 2 in the range of 40°C to 60°C, so that the separation membrane film F, which is heated in the anti-icing section 10, is dried again when it passes through the multiple heating rollers 2 arranged inside the drying chamber 31. This removes the MC solvent remaining on the surface of the separation membrane film F when it passes through the drying chamber 31.

[0052] The secondary drying section 40 maintains the temperature of the heating roller 2 in the range of 50°C to 80°C inside the drying chamber 41, so that the separation membrane film F dried in the primary drying section 30 is dried again, and the surface of the separation membrane film F in contact with it is dried again by the heating roller 2.

[0053] Furthermore, the aforementioned drying system 1 includes a stabilization process unit 50 for stabilizing the drying state of the separation membrane film F. The stabilization process unit 50 includes: a primary stabilization unit 51, which uses a clamping roller 51a disposed between the primary drying unit 30 and the secondary drying unit 40 to stabilize the transferred separation membrane film F; and a secondary stabilization unit 52, which is disposed at a subsequent process position after the secondary drying unit 40 to stabilize the transferred separation membrane film F.

[0054] The clamping roller 51a of the primary stabilization section 51 is arranged in the vertical direction to expand the transfer range of the transferred separation membrane film F, and the dry state of the surface of the separation membrane film F can be stabilized in this way.

[0055] That is, the stabilization process section 50 increases the distance between rollers 52a by vertically arranging rollers 52a, thereby widening the exposed area of ​​the separation membrane film F and thus stably maintaining the dryness of the separation membrane film F.

[0056] Thus, the drying system 1 supplies hot air and humidifies the separation membrane film F when it passes through the anti-icing section 10, unfolds the separation membrane film F when it passes through the pretreatment section 20, dries the separation membrane film F once when it passes through the primary drying section 30, stabilizes the separation membrane film F once when it passes through the primary stabilization section 51, dries the separation membrane film F a second time when it passes through the secondary drying section 40, and stabilizes the separation membrane film F a second time when it passes through the secondary stabilization section 52.

[0057] Figure 4 A diagram illustrating the heating roller of a drying system according to an embodiment of the present invention is provided. Figure 5 A diagram illustrating the internal structure of a heating roller according to an embodiment of the present invention is provided. Figure 6 A diagram illustrating the heat medium circulation state of a heating roller according to an embodiment of the present invention.

[0058] Reference Figures 4 to 6 The heating roller 2 configured in the primary drying section 30 and the secondary drying section 40 can form multiple spiral heat medium circulation pipes 2a on the inner side along the circumferential surface. The heat medium is supplied or discharged from one side to the other side or from the other side to one side along the heat medium circulation pipes 2a in the axial direction of the heating roller 2.

[0059] The heating rollers 2 mentioned above can be arranged in two to six units in the primary drying section 30, and maintain a temperature of 40°C to 60°C while in contact with the separation membrane film F to supply an appropriate drying heat source to the separation membrane film F.

[0060] The heating rollers 2 mentioned above can be arranged in 4 to 8 units in the secondary drying section 40, and maintain a temperature of 50°C to 80°C while in contact with the separation membrane film F to supply an appropriate drying heat source to the separation membrane film F.

[0061] That is, the heating roller 2 has an inlet 2b for the inflow of heating medium and an outlet 2c for the discharge of heating medium at both ends, respectively. This is a structure in which the heating roller 2 is maintained at a certain temperature by the heating medium flowing in through the inlet 2b and circulating along the heating medium circulation pipe 2a, and then the heating medium is discharged through the outlet 2c.

[0062] The aforementioned inlet 2b and outlet 2c are respectively formed at both ends of the heating roller 2, forming a structure that allows the heat medium to circulate in both directions of the heating roller 2.

[0063] Since the aforementioned heat medium circulates in a spiral shape along the axial direction of the heating roller 2, the entire surface of the heating roller 2 can be kept at a specified temperature.

[0064] Figure 7 A diagram illustrating the tension control unit of a drying system according to an embodiment of the present invention is provided. Figure 8 This diagram illustrates the operating state of the tension control unit according to an embodiment of the present invention.

[0065] Reference Figure 7 and Figure 8 The aforementioned drying system 1 includes a tension control unit 60, which is disposed outside the secondary stabilization section 52 to adjust the tension of the separation membrane film F being transferred to the next process. The tension control unit 60 includes a pair of tension rollers 61 that are in contact with the separation membrane film F and the tension of the separation membrane film F is adjusted by adjusting their positions.

[0066] Each of the rotating shafts 61a of the tension roller 61 is connected by a connecting component 62. The center of the connecting component 62 is connected to a servo motor 63, and the rotational force of the tension roller 61 can be controlled by the operation of the servo motor 63.

[0067] That is, in order to adjust the tension of the separation membrane film F, the tension control unit 60 tilts the connecting component 62 connected to it as the servo motor 63 operates, and adjusts the rotation force of the tension roller 61 by controlling the rotation shaft 61a of the tension roller 61 connected to the connecting component 62, thereby adjusting the tension of the separation membrane film F.

[0068] Thus, the tension control unit 60 of the drying system 1 is respectively configured at the inlet and outlet of the separation membrane preparation process to control the tension of the separation membrane film F. Only when the separation membrane film F maintains uniform tension when passing through multiple rollers can the MC solvent and moisture on the surface of the separation membrane film F be removed more effectively.

[0069] Therefore, the MC solvent remaining on the surface of the separation membrane film F can be more effectively recovered in the drying process of the separation membrane film F by the above-mentioned drying system 1, and the drying state of the surface of the separation membrane film F can be kept good by stabilizing the environment inside the above-mentioned drying chambers 31 and 41.

[0070] Furthermore, the temperature control of the heating roller 2 can be made easier by using a heat medium that circulates more effectively. In this way, the appropriate temperature is provided to the separation membrane film F, thereby preventing wrinkles from forming on the surface of the separation membrane film F due to melting shrinkage caused by localized high-temperature hot air.

[0071] The present invention has been described above with reference to preferred embodiments illustrated to demonstrate the principles of the invention; however, the structure and function of the invention are not limited to the content of the illustrations and description. Those skilled in the art should understand that various changes and modifications related to the present invention can be made without departing from the spirit and scope of the appended claims.

Claims

1. A drying system for preparing a separation membrane for secondary batteries, characterized in that, include: The anti-icing section, after the extraction process, heats up multiple preheating rollers located inside the preheating chamber to prevent icing on the surface of the separation membrane. In the pretreatment section, clamping rollers are used to hold both ends of the separation membrane film drawn out from the anti-icing section, and the separation membrane film is unfolded before entering the drying chamber; In the primary drying section, the temperature of multiple heating rollers arranged inside the drying chamber is maintained within the range of 40°C to 60°C, so that the separation membrane film, which has been heated in the anti-icing section, is dried again when passing through the heating rollers; and In the secondary drying section, the temperature of the heating roller is maintained in the range of 50°C to 80°C, so that the separation membrane film dried in the primary drying section is dried again. The aforementioned anti-icing section supplies hot air to the surface of the separation membrane and humidifies it through an air knife arranged adjacent to the aforementioned preheating roller; It also includes the stabilization process department, The aforementioned stabilization process includes: The primary stabilization section utilizes clamping rollers disposed between the primary drying section and the secondary drying section. These clamping rollers are arranged in a vertical direction to expand the transfer range of the transferred separation membrane film F, thereby stabilizing the transferred separation membrane film. as well as The secondary stabilization unit is located after the secondary drying unit. The secondary stabilization unit stabilizes the transferred separation membrane film by vertically arranging multiple rollers. It also includes a tension control unit, which is disposed outside the secondary stabilization section to adjust the tension of the separation membrane film being transferred to the next process; The aforementioned tension control unit includes a pair of tension rollers that contact the separation membrane film, and the tension of the separation membrane film is adjusted by adjusting their positions; Each of the rotation shafts of the tension rollers is connected by a connecting component. The center of the connecting component is connected to a servo motor. The rotation force of the tension rollers is controlled by the operation of the servo motor. That is, in order to adjust the tension of the separation membrane film F, the tension control unit tilts the connecting component connected to it as the servo motor operates. The rotation force of the tension rollers is adjusted by controlling the rotation shaft of the tension rollers connected to the connecting component, thereby adjusting the tension of the separation membrane film F.

2. The drying system for preparing a secondary battery separation membrane according to claim 1, characterized in that, The heating roller has multiple spiral heat medium circulation pipes formed on its inner side along the circumferential surface. Heat medium is supplied or discharged from one side to the other or from the other side to one side along the axial direction of the heating roller through the heat medium circulation pipes.

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