Sealing device and method for pouch-type secondary battery

Abstract

The present invention provides a sealing device for a pouch-type secondary battery and a sealing method for a pouch-type secondary battery.

Description

[Technical Field]

[0001] This application claims the benefit of the filing date of Korean Patent Application No. 10-2022-0183248, filed with the Korean Intellectual Property Office on December 23, 2022, the entire contents of which are incorporated herein by reference.

[0002] The present invention relates to a sealing device and a sealing method for a pouch-type secondary battery. [Background technology]

[0003] Demand for secondary batteries in electric vehicles, mobile devices, etc. is rapidly expanding, and the need for state diagnosis and quality stability of secondary batteries is increasing. Secondary batteries can be divided into nickel-cadmium batteries, nickel-metal hydride batteries, nickel-metal hydride batteries, lithium secondary batteries, etc.

[0004] Such lithium secondary batteries are widely used in advanced electronic devices such as phones, laptops, PCs, and camcorders. The secondary batteries can be classified into can-type secondary batteries, in which the electrode assembly is housed in a metal can, and pouch-type secondary batteries, in which the electrode assembly is housed in a pouch.

[0005] The pouch-type secondary battery includes an electrode assembly, electrode leads connected to the electrode assembly, and a pouch that houses the electrode assembly with the ends of the electrode leads extended to the outside. The electrode assembly has a structure in which electrodes and separators are alternately stacked, and the pouch includes a housing that houses the electrode assembly and a sealing part that seals the housing.

[0006] In this case, since the electrode lead is relatively thick, an additional pre-sealing process is required to seal the electrode lead and pouch section. Furthermore, due to the difference in thickness between the electrode lead and pouch section and the pouch and pouch section, an unsealed area is generated at the end of the electrode lead and pouch section, which causes a problem of electrolyte leakage outside the pouch.

[0007] Therefore, there is a need for a technology that is efficient in terms of process and prevents the occurrence of unsealed areas between the electrode lead and the pouch. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] Korean Patent Application Publication No. 10-2018-0023185 Summary of the Invention [Problem to be solved by the invention]

[0009] SUMMARY OF THE INVENTION An object of the present invention is to provide a sealing device for a pouch-type secondary battery and a sealing method for a pouch-type secondary battery for efficiently sealing an electrode lead and a pouch section. [Means for solving the problem]

[0010] One embodiment of the present invention provides a sealing device for a pouch-type secondary battery including a sealing unit, the sealing device including: a moving unit that moves the pouch-type secondary battery in one direction; a pressure unit that includes an elastic body that applies pressure to at least one surface of the sealing unit; and a heating unit that heats the sealing unit.

[0011] Another embodiment of the present invention provides a sealing method for a pouch-type secondary battery including a sealing part, the method including the steps of: moving the pouch-type secondary battery in one direction; heating at least one surface of the sealing part of the pouch-type secondary battery moving in the one direction; and pressing at least one surface of the sealing part of the pouch-type secondary battery moving in the one direction against an elastic body. [Effects of the Invention]

[0012] The sealing device and sealing method for a pouch-type secondary battery according to embodiments of the present invention can prevent the occurrence of unsealed areas and reduce the possibility of defects due to the problem of electrolyte leaking out of the pouch.

[0013] The pouch-type secondary battery sealing device and pouch-type secondary battery sealing method according to the embodiments of the present invention enable efficient process management.

[0014] The pouch-type secondary battery sealing device and pouch-type secondary battery sealing method according to the embodiments of the present invention can continuously seal pouch-type secondary batteries, thereby reducing the time required for sealing.

[0015] The pouch-type secondary battery manufactured using the sealing device for a secondary battery and the sealing method for a pouch-type secondary battery according to the embodiments of the present invention has excellent performance. [Brief explanation of the drawings]

[0016] [Figure 1] 1A and 1B are diagrams showing an embodiment of a sealing device and a sealing method for a pouch-type secondary battery according to the present invention. [Figure 2] 1A and 1B are diagrams showing a conventional sealing device and method for a pouch-type secondary battery. [Figure 3]3 is a more enlarged view of an electrode lead and a pouch section being sealed by a sealing device and a sealing method for a pouch-type secondary battery according to the present invention; FIG. [Explanation of symbols]

[0017] 1. Elastic body 1a, 1b: Traveling rollers 2, 2a, 2b Heater 3, 3a, 3b...Pressure roller 4. Pouch-type secondary battery DETAILED DESCRIPTION OF THE INVENTION

[0018] Although the present invention may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein, the present invention will be described in detail below so that those skilled in the art can easily practice the present invention.

[0019] In this specification, when a part is said to "comprise" a certain component, this does not mean that it may further include other components, unless specifically stated to the contrary, but rather that it does not exclude other components.

[0020] In this specification, "p to q" means "not less than p and not more than q."

[0021] In this specification, the term "sealing portion" refers to a region of a pouch that is sealed to seal the pouch containing the electrode assembly. The sealing portion may include an electrode lead and pouch section and a pouch and pouch section, as described below.

[0022] In this specification, the term "electrode lead and pouch section" refers to the sealed area where the electrode lead and pouch are sealed, and refers to the area corresponding to the distance from one end of the electrode lead to the other end based on the movement direction of the pouch-type battery.

[0023] In addition, in this specification, the term "pouch and pouch section" refers to the pouch and the area where the pouch is sealed in the sealed area, and refers to the area where the electrode lead and pouch section are excluded.

[0024] In describing the present invention, detailed descriptions of related known technologies that may unnecessarily obscure the gist of the present invention will be omitted.

[0025] <Sealing device for pouch-type secondary batteries> One embodiment of the present invention is a sealing device for a pouch-type secondary battery, which includes a sealing unit, and is characterized in that the sealing unit is pressed by a pressing unit including an elastic body. When the sealing unit is pressed by the elastic body, the sealing unit and the pressing unit are closely attached to each other. This prevents the occurrence of unsealed areas, such as areas where steps occur, such as the boundary between the electrode lead and the pouch.

[0026] In one embodiment of the present invention, the moving unit may be a conveyor belt, which may make it easier to continuously move the pouch-type secondary batteries.

[0027] In one embodiment of the present invention, the pressure unit may be installed along the one direction.

[0028] In an embodiment of the present invention, the pressing unit may further include a pressing roller. The pressing roller may apply additional pressure to the sealing unit while the elastic body presses the sealing unit. That is, the pressing roller may also press at least one side of the sealing unit.

[0029] In one embodiment of the present invention, the elastic body may be a flexible band. In this specification, "flexible" means that the elastic body has the property of being stretchable and deformed when a predetermined pressure or load is applied, but returning to its original shape when the predetermined pressure or load is removed. When a material has such properties, it may be referred to as an elastic body.

[0030] In one embodiment of the present invention, the pressure applying portion may include a pair of elastic bodies.

[0031] In one embodiment of the present invention, the pressure unit may further include a pair of pressure rollers.

[0032] That is, the sealing device for a pouch-type secondary battery according to an embodiment of the present invention may pressurize both sides of the sealing portion.

[0033] In one embodiment of the present invention, the heating unit may include a heater.

[0034] The heater may heat at least one side of the sealing portion. In addition, in order to improve sealing efficiency, the heating portion may include a pair of heaters. That is, both sides of the sealing portion may be heated.

[0035] That is, one embodiment of the present invention provides a sealing device for a pouch-type secondary battery, comprising: a conveyor belt that moves the pouch-type secondary battery in one direction; an elastic body that is installed along the one direction in which the pouch-type secondary battery moves and that contacts at least one surface of a sealing part; a heater that heats at least one surface of the sealing part; and a pressure roller that pressurizes at least one surface of the sealing part heated by the heater.

[0036] One embodiment of the present invention provides a sealing device for pouch-type secondary batteries, comprising: a conveyor belt that moves the pouch-type secondary batteries in one direction; a pair of elastic bodies that are installed along the one direction in which the pouch-type secondary batteries move and that come into contact with a sealing part; a pair of heaters that heat the sealing part; and a pair of pressure rollers that pressurize the sealing part heated by the pair of heaters.

[0037] The sealing device for pouch-type secondary batteries according to an embodiment of the present invention seals pouch-type secondary batteries while moving them in one direction using a conveyor belt, preventing the occurrence of unsealed areas and reducing the possibility of defects due to electrolyte leakage outside the pouch. Furthermore, since the sealing is performed in a continuous process, efficient process management is possible and the sealing time can be reduced.

[0038] As a result, the pouch-type secondary battery manufactured using the sealing apparatus for a secondary battery according to an embodiment of the present invention has excellent performance.

[0039] In an embodiment of the present invention, a pair of heaters for heating the sealing portion and a pair of pressure rollers for pressing the sealing portion heated by the pair of heaters may be disposed inside the elastic body. Disposing inside the elastic body means that the heat generated by the heaters and the pressure generated by the pressure rollers are transmitted to the sealing portion through the elastic body.

[0040] The sealing device for a pouch-type secondary battery according to an embodiment of the present invention may include a traveling roller for moving the elastic body along a predetermined path.

[0041] That is, in an embodiment of the present invention, the elastic body may include a traveling roller. The traveling roller allows the elastic body to continuously move along a predetermined path. That is, the traveling roller allows the elastic body to circulate within the predetermined path. The traveling roller may be a pair of rollers.

[0042] In this specification, the predetermined path may be referred to as a circulation path of the elastic body. As the elastic body moves along the circulation path, the heat generated by the heater and the pressure generated by the pressure roller can be continuously transferred to the sealing portion passing through the elastic body.

[0043] That is, in an embodiment of the present invention, the pressure unit may include an elastic body, and the elastic body may include a running roller, a heater, and a pressure roller therein. In this case, the running roller, the heater, and the pressure roller may each be formed in a pair.

[0044] In an embodiment of the present invention, the length of the elastic body may be 0.5 m to 1.5 m or less, but is not limited thereto, and the length may be determined depending on the size of the sealing device, the size of the pouch-type secondary battery, etc.

[0045] In one embodiment of the present invention, the sealing unit may include an electrode lead and a pouch section. That is, in the sealing device for a secondary battery according to an embodiment of the present invention, the section where the electrode lead and the pouch are located together among the areas requiring sealing may be a primary sealing target, but is not limited thereto, and the pouch and the pouch section may also be the sealing unit.

[0046] In an embodiment of the present invention, the Young's modulus of the elastic body may be 0.01 GPa to 1.0 GPa, preferably 0.01 GPa to 0.8 GPa, and more preferably 0.01 GPa to 0.6 GPa. The closer the elastic body is to rubber properties, the more effectively it can contact the sealing part. The fact that the elastic body satisfies the Young's modulus range means that the elastic body is close to rubber properties, i.e., when the elastic body satisfies the Young's modulus range, sealing can be performed more efficiently.

[0047] In an embodiment of the present invention, the elastic body may be polytetrafluoroethylene (PTFE). Polytetrafluoroethylene (PTFE), also known as Teflon (registered trademark), is a crystalline material with high thermal stability and chemical resistance. That is, when the elastic body is PTFE, the heat transferred by the heater can be transferred to the sealing part without causing damage to the elastic body itself. That is, it has the advantage of being able to improve sealing efficiency and be used for a long period of time.

[0048] In addition, since it has high thermal stability and chemical resistance, it is advantageously applied to sealing of electrode leads and pouch sections that must be heated and pressurized at relatively high temperatures.

[0049] In an embodiment of the present invention, the temperature condition of the heating unit may be 200° C. to 250° C., preferably 200° C. to 240° C., and more preferably 210° C. to 230° C. The temperature condition refers to the temperature condition at which the heating unit heats the sealing unit, and by satisfying the condition, the electrode lead and pouch section can be effectively sealed.

[0050] In an embodiment of the present invention, the pressure condition of the pressure applying unit may be 0.1 MPa to 1.5 MPa, preferably 0.2 MPa to 1.3 MPa, more preferably 0.3 MPa to 1.0 MPa. By satisfying the pressure condition, the electrode lead and pouch section can be effectively sealed. In this case, the pressure condition may be the pressure applied to the sealing portion by the pressure roller, and the elastic body can effectively transmit the pressure from the pressure roller to the sealing portion, i.e., the elastic body can adhere closely to the sealing portion, thereby preventing the occurrence of an area where pressure is not applied.

[0051] In addition, the sealing portion may be heated and then pressurized. Since the sealing portion is formed by melting a portion of the pouch and then applying pressure to the melted portion, it may be preferable to heat the sealing portion and then pressurize the heated sealing portion, but as long as sealing can be performed, pressurization of the sealing portion may be performed simultaneously with heating.

[0052] In this specification, the pouch-type secondary battery contains an electrode assembly inside the pouch. The electrode assembly refers to a chargeable / dischargeable power generating element having a laminated structure of electrodes and a separator, and can be roughly classified into a jelly-roll type in which a separator is interposed between sheet-like positive and negative electrodes coated with an active material and wound up, a stack type in which multiple positive and negative electrodes are stacked in sequence with a separator interposed therebetween, and a stack-and-fold type in which stack-type unit cells are wound up around a long separator film.

[0053] <Sealing method for pouch-type secondary batteries> One embodiment of the present invention is a method for sealing a pouch-type secondary battery including a sealing part, which comprises heating the sealing part and applying pressure with an elastic body while the secondary battery is moving in one direction. By applying pressure to the sealing part with the elastic body, it is possible to prevent the occurrence of unsealed areas (non-sealed areas) at areas where steps occur, such as the boundary between an electrode lead and a pouch.

[0054] As described above, the elastic body may be a flexible band, the sealing portion may be pressed by the pressure roller, and the sealing portion may be heated by the heater. The secondary battery may be moved by a conveyor belt. The elastic body, pressure roller, and heater may be configured as a pair, but are not limited thereto.

[0055] Furthermore, as long as sealing can be achieved, pressure may be applied to the sealed portion simultaneously with heating, but preferably pressure may be applied after heating.

[0056] In this case, one embodiment of the present invention provides a sealing method for a pouch-type secondary battery, which seals a pouch containing an electrode assembly, comprising: moving the pouch-type secondary battery in one direction using a conveyor belt; and passing a sealing unit of the pouch-type secondary battery, which is moving using the conveyor belt, between a pair of elastic bodies; wherein the step of passing the sealing unit of the pouch-type secondary battery, which is moving using the conveyor belt, between the pair of elastic bodies includes: heating the sealing unit while the sealing unit passes between the pair of elastic bodies; and pressurizing the sealing unit heated by the pair of heaters while the sealing unit passes between the pair of elastic bodies.

[0057] In one embodiment of the present invention, the moving speed of the pouch-type secondary battery in the step of moving the pouch-type secondary battery in one direction may be 5 m / min to 20 m / min, preferably 8 m / min to 15 m / min, and more preferably 10 m / min to 15 m / min. More specifically, the step of moving the pouch-type secondary battery in one direction may use a conveyor belt, and the moving speed may refer to the moving speed of the conveyor belt. Meeting the moving speed may enable effective sealing of the electrode lead and pouch section. That is, if the moving speed of the conveyor belt is faster than the above speed, an unsealed section may occur. That is, if the moving speed of the conveyor belt is slower than the above speed, the heating and pressurizing time may be prolonged, which may cause unnecessary damage.

[0058] In one embodiment of the present invention, the step of applying pressure to at least one surface of the sealing portion of the pouch-type secondary battery moving in one direction with an elastic body may be performed for 1 to 15 seconds, preferably 1 to 12 seconds, and more preferably 1 to 6 seconds, based on a length of 1 m of the elastic body, so that one sealing portion passes through, but is not limited thereto, and the conditions may be determined depending on the size of the sealing device, the size of the pouch-type secondary battery, etc.

[0059] In this specification, the description of the sealing device for a pouch-type secondary battery described above may be applied to the sealing method for a pouch-type secondary battery, and vice versa.

[0060] The present invention will be described in more detail below with reference to Fig. 1. Fig. 1 is a diagram showing an embodiment of a pouch-type secondary battery sealing device and a pouch-type secondary battery sealing method according to the present invention. Specifically, the diagram shows a case where an elastic body, a heater, a pressure roller, and a traveling roller are provided in pairs as an example, but the present invention is not limited to this.

[0061] As shown in FIG. 1, a pouch-type secondary battery 4 is moved in one direction (corresponding to the traveling direction in FIG. 1) using a conveyor belt (not shown), and sealing begins. FIG. 1 illustrates a case where the sealing position (sealing portion) of the pouch-type secondary battery is located between the electrode lead and pouch. As the pouch-type secondary battery 4 moves along the conveyor belt, the sealing portion passes between a pair of elastic bodies 1 (flexible bands). The elastic body 1 may include a pair of traveling rollers 1a and 1b; a heater 2; and a pressure roller 3. That is, the sealing portion can be heated and pressurized by the heater 2 and pressure roller 3 as it passes between the elastic bodies 1. More specifically, the heater 2 and pressure roller 3 are disposed inside the elastic body 1, so that the heat generated by the heater 2 and the pressure generated by the pressure roller 3 can be transferred to the sealing portion via the elastic body 1. In this case, the elastic body 1 can uniformly transfer heat and pressure to the sealing portion, preventing the occurrence of unsealed areas. At this time, the pair of traveling rollers 1a and 1b are located inside the end of the elastic body 1, allowing the elastic body 1 to continuously move along a predetermined path (circulation path). As the elastic body 1 moves along the circulation path, the heat generated by the heater 2 and the pressure generated by the pressure roller 3 can be transferred to the sealing portion that continuously passes through the elastic body 1.

[0062] FIG. 2 illustrates a sealing device and sealing method for a conventional pouch-type secondary battery. FIG. 2 also illustrates an example of the electrode lead and pouch section, and it was found that in the conventional method, an unsealed area occurs at the boundary between the electrode lead and the pouch (shown by the dotted circle, A'). That is, a sealing device for a conventional pouch-type secondary battery may have a structure in which, while maintaining a 45° angle between section B in height, the area where the sealing device contacts the sealing portion of the pouch changes from E to D, and while maintaining a 45° angle between section A in height, the area where the sealing device contacts the sealing portion changes from D to C. However, even when the sealing portion is heated and pressurized using this conventional sealing device for a pouch-type secondary battery, an unsealed area may occur at the boundary between the electrode lead and the pouch (shown by the dotted circle, A'). The 45° angle in FIG. 2 corresponds to an example and may be changed depending on the shape of the pouch.

[0063] 1 and 2, it can be seen that the sealing device and method for a pouch-type secondary battery according to the present invention are capable of efficient sealing, and that the efficiency is particularly high when the electrode lead and pouch section are the sealing portion. High sealing efficiency means that there is a lower possibility of an unsealed area occurring.

[0064] FIG. 3 is a more enlarged view of the electrode lead and pouch section being sealed in the pouch-type secondary battery sealing device and pouch-type secondary battery sealing method according to the present invention. Again, this example illustrates a pair of each configuration. In other words, FIG. 3 is a more enlarged view of the electrode lead and pouch section being sealed in FIG. 1. As shown in FIG. 3, sealing is performed using heaters 2a, 2b and pressure rollers 3a, 3b, respectively, disposed inside a pair of elastic bodies (not shown). Because the elastic bodies can effectively transfer heat and pressure to the boundary A' between the electrode lead and pouch, both the boundary A' between the electrode lead and pouch and the section B that is not the boundary between the electrode lead and pouch can be effectively sealed.

[0065] In one embodiment of the present invention, the pouch may contain polypropylene. That is, the sealing is performed by applying pressure to the polypropylene contained in the pouch in a melted state due to heat, and then solidifying the polypropylene as the temperature drops. Therefore, as described above, although heating and pressure may be applied to the sealing portion simultaneously, it is preferable to apply pressure to the sealing portion after heating.

[0066] In this specification, except for using the above-described pouch-type secondary battery sealing device and pouch-type secondary battery sealing method, methods, materials, devices, etc. commonly used in the relevant field may be used.

Claims

1. A sealing device for a pouch-type secondary battery including a sealing part, a moving unit that moves the pouch-type secondary battery in one direction; a pressure applying unit including an elastic body that applies pressure to at least one surface of the sealing unit; a heating unit that heats the sealing unit; and a travel roller for moving the elastic body along a predetermined path; A sealing device for a pouch-type secondary battery, comprising:

2. The sealing device for a pouch-type secondary battery according to claim 1 , wherein the sealing part includes an electrode lead and a pouch section.

3. 2. The sealing device for a pouch-type secondary battery according to claim 1, wherein the Young's modulus of the elastic body is 0.01 GPa to 1 GPa.

4. The sealing device for a pouch-type secondary battery according to claim 1 , wherein the elastic body is polytetrafluoroethylene (PTFE).

5. A sealing method for a pouch-type secondary battery including a sealing portion, comprising: moving the pouch-type secondary battery in one direction; heating at least one surface of the sealing portion of the pouch-type secondary battery moving in one direction; and pressing at least one surface of the sealing portion of the pouch-type secondary battery moving in one direction with an elastic body moved along a predetermined path by a traveling roller; A method for sealing a pouch-type secondary battery, comprising:

6. 6. The method of claim 5, wherein the moving speed of the pouch-type secondary battery in the step of moving the pouch-type secondary battery in one direction is 5 m / min to 20 m / min.

7. 6. The method of claim 5, wherein the step of pressing at least one surface of the sealing portion of the pouch-type secondary battery moving in one direction with an elastic body is performed so that one sealing portion passes through the elastic body for 1 to 15 seconds based on a length of 1 meter.

8. A sealing method for a pouch-type secondary battery as described in Claim 5, wherein the temperature condition of the heating step is 200°C to 250°C.

9. A sealing method for a pouch-type secondary battery as described in Claim 5, wherein the pressure conditions in the pressurizing step are 0.1 MPa to 1.5 MPa.

10. A method for manufacturing a pouch-type secondary battery, comprising the method for sealing a pouch-type secondary battery according to any one of claims 5 to 9.

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