Sealing device for pouch-type secondary battery and sealing 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 for a pouch-type secondary battery and a sealing method for a pouch-type secondary battery. [Background technology]

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

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

[0005] The pouch-type secondary battery includes an electrode assembly, an electrode lead connected to the electrode assembly, and a pouch accommodating the electrode assembly with the ends of the electrode leads extended to the outside, the electrode assembly having a structure in which electrodes and separators are alternately stacked, and the pouch includes a receiving portion that accommodates the electrode assembly and a sealing portion that seals the receiving portion to hermetically close the receiving portion.

[0006] At this time, since the electrode lead is relatively thick, a pre-sealing process is additionally required for sealing the electrode lead and pouch section, and since there is a difference in thickness between the electrode lead and pouch section and the pouch and pouch section, an area that is not sealed (non-sealed area) occurs at the end portion of the electrode lead and pouch section, which causes a problem that the electrolyte leaks out of the pouch.

[0007] Therefore, there is a need for a technology that is process-efficient 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 PRESENT EMBODIMENT 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 side of the sealing unit; and a heating unit that heats the sealing unit.

[0011] Also, one embodiment of the present invention provides a sealing method for a pouch-type secondary battery including a sealing part, comprising 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. Effect of the Invention

[0012] The sealing device and sealing method for a pouch-type secondary battery according to the 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 apparatus and the 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 apparatus and method according to the embodiments of the present invention can continuously seal the pouch-type secondary batteries, thereby reducing the time required for sealing.

[0015] The pouch-type secondary battery manufactured using the sealing apparatus 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 description of the drawings]

[0016] [Figure 1] 1A to 1C are diagrams showing an embodiment of a sealing device and a sealing method for a pouch-type secondary battery according to the present invention; [Diagram 2] 1A to 1C are diagrams showing a conventional sealing device and method for a pouch-type secondary battery. [Diagram 3]4 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 PREFERRED EMBODIMENTS

[0018] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will now be described in detail so that those skilled in the art can easily practice the present invention. However, the present invention may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein.

[0019] In this specification, when a part is said to "comprise" a certain component, this means that it may further include other components, rather than excluding other components, unless specifically stated to the contrary.

[0020] In this specification, "p to q" means "greater than or equal to p and less than or equal to q."

[0021] In the present specification, the term "sealing portion" refers to a region of a pouch that is sealed to seal the pouch housing an 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 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, "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 in the sealed area.

[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 including a sealing part, characterized in that the sealing part is pressurized by a pressurizing part including an elastic body. When the sealing part is pressurized by the elastic body, the sealing part and the pressurizing part are in close contact with each other. This makes it possible to prevent the occurrence of an unsealed area (non-sealed area) in a part where a step occurs, such as the boundary between an electrode lead and a pouch.

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

[0027] In one embodiment of the present invention, the pressure applying portion may be disposed 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 when 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, the term "flexible" means that the elastic body has a property of being stretchable and deformed when a certain pressure or load is applied, but returning to its original shape when the certain pressure or load is removed. When a material having such a property is used, it may be expressed as an elastic body.

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

[0031] In an 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 apply pressure to 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 surface of the sealing portion. In addition, in order to improve sealing efficiency, the heating portion may include a pair of heaters. That is, both surfaces 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 for moving the pouch-type secondary battery in one direction; an elastic body installed along the one direction in which the pouch-type secondary battery moves and in contact with at least one surface of a sealing part; a heater for heating at least one surface of the sealing part; and a pressure roller for applying pressure to at least one surface of the sealing part heated by the heater.

[0036] One embodiment of the present invention provides a sealing device for a pouch-type secondary battery, comprising: a conveyor belt for moving the pouch-type secondary battery in one direction; a pair of elastic bodies installed along the one direction in which the pouch-type secondary battery moves and in contact with a sealing part; a pair of heaters for heating the sealing part; and a pair of pressure rollers for applying pressure to the sealing part heated by the pair of heaters.

[0037] The pouch-type secondary battery sealing device according to an embodiment of the present invention seals the pouch-type secondary battery while moving it in one direction using a conveyor belt, thereby preventing the occurrence of unsealed areas and reducing the possibility of defects due to the problem of electrolyte leaking out of the pouch. In addition, since the sealing is performed in a continuous process, efficient process management is possible and the time required for sealing 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 part and a pair of pressure rollers for pressing the sealing part heated by the pair of heaters may be disposed inside the elastic body. Disposed inside the elastic body means a structure in which the heat generated by the heaters and the pressure generated by the pressure rollers are transferred to the sealing part 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 elastic body 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. The elastic body moves along the circulation path, so that the heat generated by the heater and the pressure generated by the pressure roller can be continuously transferred to the sealing part 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 part 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, a section where the electrode lead and the pouch are located together among areas requiring sealing may be a main sealing target, but is not limited thereto, and the pouch and the pouch section may also be a sealing part.

[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, and the elastic body satisfying the Young's modulus range means that the elastic body is close to rubber properties, that is, 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) is also called Teflon (registered trademark) and is a crystalline material having high thermal stability and chemical resistance. That is, when the elastic body is PTFE, the heat transferred by the heater may be transferred to the sealing part without causing damage to the elastic body itself. That is, there is an advantage that the sealing efficiency is improved and the elastic body can 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 part may be 200° C. to 250° C., preferably 200° C. to 240° C., and more preferably 210° C. to 230° C. The temperature condition means a temperature condition under which the heating part heats the sealing part, and by satisfying the condition, sealing of the electrode lead and pouch section can be effectively performed.

[0050] In an embodiment of the present invention, the pressure condition of the pressure unit may be 0.1 MPa to 1.5 MPa, preferably 0.2 MPa to 1.3 MPa, and more preferably 0.3 MPa to 1.0 MPa. By satisfying the pressure condition, sealing of the electrode lead and the pouch section can be effectively performed. In this case, the pressure condition may be a pressure applied to the sealing part by the pressure roller, and the elastic body can effectively transmit the pressure from the pressure roller to the sealing part, i.e., the elastic body can be in close contact with the sealing part to prevent the occurrence of an area where pressure is not applied.

[0051] Also, the sealing part may be heated and pressurized to the heated sealing part. The sealing part is formed by melting a part of the pouch and then applying pressure to the melted part, so it may be preferable to heat the sealing part and apply pressure to the heated sealing part, but as long as sealing can be performed, pressure may be applied to the sealing part simultaneously with heating.

[0052] In this specification, the pouch-type secondary battery accommodates an electrode assembly inside the pouch. The electrode assembly means 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 a sheet-like positive electrode and a sheet-like negative electrode coated with an active material and wound up, a stack type in which a number of positive electrodes and anodes are stacked in sequence with a separator interposed therebetween, and a stack-and-fold type in which a stack-type unit cell is wound up on 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 is characterized in that the sealing part is heated and pressurized with an elastic body while the secondary battery is moving in one direction. By pressing the sealing part with the elastic body, it is possible to prevent the occurrence of unsealed areas (non-sealed areas) in areas where steps occur, such as the boundary between the electrode lead and the 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, the pressure roller, and the heater may be formed as a pair, but are not limited thereto.

[0055] In addition, as long as sealing can be performed, 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 portion of the pouch-type secondary battery moving using the conveyor belt between a pair of elastic bodies; wherein the step of passing the sealing portion of the pouch-type secondary battery moving using the conveyor belt between a pair of elastic bodies includes: heating the sealing portion while the sealing portion passes between the pair of elastic bodies; and pressurizing the sealing portion heated by the pair of heaters while the sealing portion 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. By satisfying the moving speed, sealing of the electrode lead and the pouch section can be effectively performed. That is, if the moving speed of the conveyor belt is faster than the speed, a non-sealed section may occur, and if the moving speed of the conveyor belt is slower than the speed, the heating and pressurizing time may be longer, and unnecessary damage may occur.

[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 apparatus 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 sealing device and a sealing method for a pouch-type secondary battery according to the present invention. Specifically, the figure shows a case where an elastic body, a heater, a pressure roller, and a running roller are in a pair as an example, but is not limited thereto.

[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) to start sealing. FIG. 1 is a diagram illustrating a case where a sealing position (sealing part) of the pouch-type secondary battery is an electrode lead and pouch section. In this manner, the sealing part of the pouch-type secondary battery 4 moving through the conveyor belt passes between a pair of elastic bodies 1 (flexible bands). The elastic body 1 may include a pair of traveling rollers 1a, 1b; a heater 2; and a pressure roller 3. That is, the sealing part may be heated and pressurized by the heater 2; and the pressure roller 3 while passing between the elastic bodies 1. More specifically, the heater 2; and the 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 may be transferred to the sealing part through 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 passes continuously through the elastic body 1.

[0062] FIG. 2 is a diagram showing a sealing device for a pouch-type secondary battery and a sealing method for the pouch-type secondary battery. FIG. 2 also illustrates an example of an electrode lead and pouch section, and it was confirmed that in the case of the conventional method, an unsealed area occurs at the boundary between the electrode lead and the pouch (shown by a dotted circle, A'). That is, the sealing device for a pouch-type secondary battery in the related art may have a structure in which, while maintaining a 45° angle between section B on a height basis, the area where the sealing device abuts against the sealing part of the pouch changes from E to D, and, while maintaining a 45° angle between section A on a height basis, the area where the sealing device abuts against the sealing part changes from D to C. However, even if the sealing part is heated and pressurized in such a 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 a dotted circle, A'). The 45° angle in FIG. 2 corresponds to an example, and may be changed according to the shape of the pouch.

[0063] That is, by comparing Figures 1 and 2, it was confirmed that the sealing device and sealing method for a pouch-type secondary battery according to the present invention are capable of efficient sealing, and in particular, when the electrode lead and pouch section are the sealing portion, the efficiency is higher. High sealing efficiency means that there is a lower possibility of non-sealed areas occurring.

[0064] FIG. 3 is a more enlarged view of the electrode lead and pouch section sealed in the pouch-type secondary battery sealing device and pouch-type secondary battery sealing method according to the present invention. In this case, the case where each configuration is a pair is also illustrated as an example. In other words, FIG. 3 is a more enlarged view of the electrode lead and pouch section sealed in FIG. 1. As shown in FIG. 3, the electrode lead and pouch section are sealed by heaters 2a, 2b and pressure rollers 3a, 3b respectively arranged inside a pair of elastic bodies (not shown), and the elastic bodies can effectively transfer heat and pressure to the boundary A' between the electrode lead and the pouch, so that both the boundary A' between the electrode lead and the pouch and the section B that is not the boundary between the electrode lead and the pouch can be effectively sealed.

[0065] In one embodiment of the present invention, the pouch may include polypropylene. That is, the sealing is performed by applying pressure to the polypropylene contained in the pouch in a melted state by heat, and then solidifying the polypropylene again as the temperature drops. Therefore, as described above, the sealing portion may be heated and pressurized at the same time, but it is preferable to apply pressure after heating the sealing portion.

[0066] In this specification, except for using the above-mentioned 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 pressurizing part including an elastic body that presses at least one surface of the sealing part; and a heating unit for heating the sealing unit; 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 elastic body has a Young's Modulus of 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. 2. The pouch-type secondary battery sealing device according to claim 1, wherein the temperature condition of the heating unit is 200°C to 250°C.

6. 2. The sealing device for a pouch-type secondary battery according to claim 1, wherein a pressure condition of the pressurizing unit is 0.1 MPa to 1.5 MPa.

7. A method for sealing 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; A method for sealing a pouch-type secondary battery, comprising:

8. 8. The method of claim 7, wherein a 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.

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

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