Sealing device for pouch-type secondary batteries

Abstract

The present invention relates to a sealing device for a pouch-type secondary battery, which includes a light source unit that irradiates light and a pressurizing unit that heats and pressurizes the sealed portion of a pouch case using the light irradiated from the light source unit. The sealing unit of the pressurizing unit that is in contact with the sealed portion of the case uses a first light-transmitting material with high thermal conductivity and optical refractive index, which not only enables uniform sealing of the sealed portion of the case but also prevents damage to the sealing unit that is heated to a high temperature during sealing, thereby improving the quality of the secondary battery and at the same time improving processability and economy.

Description

[Technical Field]

[0001] The present invention relates to a sealing device used to seal a case during the manufacture of a pouch-type secondary battery.This application claims the benefit of priority based on Korean Patent Application No. 10-2022-0106088, filed on August 24, 2022, and all contents disclosed in the documents of this Korean patent application are incorporated herein by reference. [Background technology]

[0002] In recent years, as devices using batteries have become more diverse, the demand for high-capacity, high-density batteries has increased. Among these, lithium secondary batteries, which have high energy density and discharge voltage, have been commercially available and used in various forms.

[0003] Lithium secondary batteries are classified into cylindrical secondary batteries, prismatic secondary batteries, and pouch-type secondary batteries according to their external shape. Among them, pouch-type secondary batteries are being researched in various fields because they can be manufactured in various shapes and have high capacity and high density by adjusting the thickness of the aluminum laminate sheet.

[0004] Pouch-type secondary batteries are generally formed by forming a housing from an aluminum laminate sheet, housing an electrode assembly in the housing, and then sealing the periphery of the housing. To seal the periphery of the housing and form the sealed portion, conventional sealing devices for pouch-type secondary batteries apply pressure and heat using a single member.

[0005] In a conventional sealing device for a pouch-type secondary battery, the sealing portion of a pouch-type secondary battery case made of a laminate sheet including an outer resin layer, a metal layer, and an inner sealant layer is arranged so that the inner sealant layer faces the sealing portion, and then the sealed portion is placed between a pressure unit that can simultaneously apply heat and pressure to seal the battery case. However, this sealing device has a problem in that it takes a long time for heat to be transferred from the outer resin layer to the inner sealant layer, which can cause damage to the outer resin layer.

[0006] To solve these problems, a method for sealing a pouch-type secondary battery using a laser has been developed. Similar to conventional pouch-type secondary battery sealing devices, the pouch-type secondary battery sealing device arranges the sealing parts of a pouch-type secondary battery case, including an outer resin layer, a metal layer, and an inner sealant layer, with the inner sealant layer facing each other, and then places the battery between pressure units.

[0007] The pressurizing unit is made of an infrared-transmitting material and has an infrared irradiator on top. The infrared irradiator rapidly heats only the metal layer of the sealing part of the secondary battery case, melting the inner sealant layer with the heated metal layer, thereby improving sealing strength while reducing damage to the outer resin layer caused by heat.

[0008] However, the sealing device for the pouch-type secondary battery has a limitation in that it cannot heat the metal layer disposed between the outer resin layer and the inner sealant layer unless the laser output is high. Furthermore, uneven heating of the pressure applying part can lead to uneven sealing or quality imbalances such as wrinkles in the laminate sheet that constitutes the case. Increasing the laser output to address this issue can lead to problems such as damage to the pressure applying part when pressed in a heated state due to the low compressive strength of the pressure applying part.

[0009] Therefore, there is a need for the development of a pouch-type secondary battery sealing device and a pouch-type secondary battery manufacturing method that can uniformly and safely seal the sealed portion of the pouch-type secondary battery case. [Prior art documents] [Patent documents]

[0010] [Patent Document 1] Korean Patent Publication No. 10-2021-0156516 Summary of the Invention [Problem to be solved by the invention]

[0011] SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a sealing device for a pouch-type secondary battery that can uniformly and safely seal the sealed portion of a pouch-type secondary battery case, and a method for manufacturing a secondary battery using the same. [Means for solving the problem]

[0012] To solve the above-mentioned problems, In one embodiment, the present invention comprises: a pressure applying part located at least at one of the upper and lower parts of the sealed part of the pouch case and made of a material through which a light source can pass; a light source unit that irradiates the pressure applying unit with light, The pressure unit provides a sealing device for a pouch-type secondary battery, which includes a first light-transmitting material that satisfies the following formula 1:

[0013] [Formula 1] 15≦TC 1st / RI 1st ≦35

[0014] In Equation 1, TC 1st indicates the thermal conductivity of the first light-transmitting material (unit: W / m K), RI 1st indicates the refractive index of the first light-transmitting material for light having a wavelength of 980 nm.

[0015] In this case, the first light transmitting material may have a refractive index of 1.45 to 1.9 for light having a wavelength of 980 nm, and may exhibit a Mohs hardness of 8.0 or higher.

[0016] The pressurizing unit may include a sealing unit that contacts the sealed portion of the pouch case and heat-presses it, and a lens unit that is positioned between the light source unit and the sealing unit and focuses light irradiated from the light source unit onto the sealing unit, and the sealing unit may include the first light-transmitting material.

[0017] Furthermore, the lens unit may include one or more of the first light-transmitting material and the second light-transmitting material, and the second light-transmitting material may satisfy formula 2.

[0018] [Formula 2] 0.5≦TC 2nd / RI 2nd ≦2

[0019] In Equation 2, TC 2nd indicates the thermal conductivity of the second light-transmitting material (unit: W / m K), RI 2nd indicates the refractive index of the second light-transmitting material for light having a wavelength of 980 nm.

[0020] Here, the second light transmitting material may have a refractive index of 1.40 to 1.60 for light having a wavelength of 980 nm.

[0021] The lens unit may also be a cylinder lens.

[0022] In this case, the lens unit includes the first light-transmitting material and the second light-transmitting material, and the first light-transmitting material and the second light-transmitting material may have a symmetrical structure with respect to a center line including the cross-sectional center of the lens unit.

[0023] On the other hand, the light source unit can emit light having a wavelength of 750 nm to 1,000 nm.

[0024] In one embodiment, the present invention further comprises: housing the electrode assembly and the electrolyte in a pouch-type case made of a laminate sheet including a metal layer and an inner sealant layer, the pouch-type case including an electrode assembly housing portion and a sealing portion surrounding the electrode assembly housing portion; disposing a sealing device according to the present invention at one or more points of an upper portion and a lower portion of a sealed portion of the pouch-type case; and pressing the sealing portion of the pouch-type case while irradiating light from the light source unit of the sealing device to the pressing portion to seal the pouch-type case. [Effects of the Invention]

[0025] A sealing device for a pouch-type secondary battery according to the present invention includes a light source unit that irradiates light, and a pressurizing unit that heats and pressurizes a sealed portion of a pouch case using the light irradiated from the light source unit, and the sealing unit of the pressurizing unit that contacts the sealed portion of the case is configured to use a first light-transmitting material with high thermal conductivity and optical refractive index. As a result, the sealing device can uniformly heat and seal the sealed portion of the case and prevent damage to the sealing unit that is heated to a high temperature during sealing, thereby improving the quality of the secondary battery and simultaneously improving processability and economy. [Brief explanation of the drawings]

[0026] [Figure 1] 1 is a perspective view schematically illustrating a sealing process of a pouch-type secondary battery using a light source unit and a pressure unit of a sealing device according to the present invention; [Figure 2] 3 is a cross-sectional view showing the cross-sectional structure formed by a first light transmitting material and a second light transmitting material in a lens unit including the first light transmitting material and the second light transmitting material. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0027] Because the present invention is susceptible to various modifications and can have various embodiments, specific embodiments are described in detail in the detailed description.

[0028] However, this is not intended to limit the invention to any particular embodiment, but is understood to include all modifications, equivalents, or alternatives falling within the spirit and scope of the invention.

[0029] In the present invention, the terms "comprise" and "have" are intended to specify the presence of features, numbers, steps, operations, components, parts or combinations thereof described in the specification, and are understood as not precluding the presence or possible addition of one or more other features, numbers, steps, operations, components, parts or combinations thereof.

[0030] Furthermore, in the present invention, when a layer, film, region, plate, or other portion is described as being "on" another portion, this includes not only the case where it is "directly on" the other portion, but also the case where there is another portion therebetween. Conversely, when a layer, film, region, plate, or other portion is described as being "under" the other portion, this includes not only the case where it is "directly under" the other portion, but also the case where there is another portion therebetween. Furthermore, in this application, being "located on" can include not only the case where it is located at the top, but also the case where it is located at the bottom.

[0031] The present invention will now be described in more detail.

[0032] <Sealing device for pouch-type secondary batteries> In one embodiment, the present invention comprises: a pressure applying part located at least at one of the upper and lower parts of the sealed part of the pouch case and made of a material through which a light source can pass; a light source unit that irradiates the pressure applying unit with light, The pressure unit provides a sealing device for a pouch-type secondary battery, which includes a first light-transmitting material that satisfies the following formula 1:

[0033] [Formula 1] 15≦TC 1st / RI 1st ≦35

[0034] In Equation 1, TC 1st is the thermal conductivity of the first light-transmitting material (unit: W / m K), RI 1st indicates the refractive index of the first light-transmitting material for light having a wavelength of 980 nm.

[0035] A sealing device for a pouch-type secondary battery according to the present invention includes a light source unit that irradiates light, and a pressurizing unit that heats and pressurizes a sealed portion of a pouch case using the light irradiated from the light source unit, and is characterized in that a sealing unit of the pressurizing unit that contacts the sealed portion of the case is made of a first light-transmitting material having high thermal conductivity and optical refractive index. As a result, the sealing device can not only uniformly heat and seal the sealed portion of the case, but also prevent damage to the sealing unit that is heated to a high temperature during sealing, thereby improving the quality of secondary batteries and simultaneously improving processability and economy.

[0036] 1 is a perspective view showing the main structure of a sealing device according to the present invention, which will be described in more detail below with reference to FIG.

[0037] The pouch-type secondary battery sealing device 100 includes a pressurizing unit 120 positioned on the sealed portion 11a of the pouch case 11 to heat and pressurize the sealed portion, and a light source unit 110 that irradiates light onto the pressurizing unit to heat it.

[0038] At this time, the light source unit 110 serves to heat the pressure unit. To this end, the light source unit 110 may irradiate light onto the pressure unit 120, and the irradiated light may be emitted as a laser beam. For example, the light may be generated by a laser diode, and the emitted light may be an infrared laser, specifically, an infrared laser with a wavelength of 750 nm to 1,000 nm or an infrared laser with a wavelength of 800 nm to 980 nm.

[0039] In addition, the infrared laser emitted from the light source unit 110 can be irradiated to either one of the top and bottom of the sealing portion 11a to be sealed, or can be irradiated from both the top and bottom of the sealing portion 11a. The former case has the advantage of lower equipment costs than the latter case and preventing the possibility of damage to the laser diodes on the opposing sides. The latter case has the advantage of using two light sources 110 on both sides of the sealing portion 11a, so that the sealant layer can be melted more quickly and effectively.

[0040] In addition, the light source unit 110 may be provided in plural on the side other than the side where the pressing unit 120 presses the case sealing unit 11a, and the pressing unit 120 and the light source unit 110 may be arranged on the same line on the case sealing unit 11a. In this case, even if the light source unit 110 and the pressing unit 120 are spaced apart from each other, loss of the infrared laser emitted to the pressing unit 120 may be minimized.

[0041] In addition, the light emitted from the light source unit 110 is transmitted to the pressure unit 120, and the light transmitted to the pressure unit 120 is condensed to heat the sealing unit 11a of the case.

[0042] More specifically, the pressure unit 120 applies pressure to the sealing portion 11a of the case to maintain the mutual adhesion of the sealant layer inside the case in an increased state, and in this state, the light source unit 110 emits an infrared laser to heat the pressure unit 120.

[0043] In this method, infrared rays are irradiated while maintaining a pressurized state, so that the sealant layer inside the case can be irradiated with infrared rays with high precision, and the sealing part 11a can be effectively formed, and the bonding strength of the sealing part 11a can be further increased.

[0044] In this case, the pressurizing unit 120 may include a sealing unit 121 that contacts the sealed portion 11a of the pouch case and heat-presses it, and a lens unit 122 that is located between the light source unit 110 and the sealing unit 121 and focuses the light irradiated from the light source unit 110 onto the sealing unit 121.

[0045] The sealing unit 121 pressurizes the sealed portion 11a of the case, and heats the sealed portion 11a by transferring heat generated by an infrared laser focused through the lens unit 122 to the sealed portion 11a. To this end, the sealing unit 121 may have a flat plate shape provided along the sealed portion 11a of the case, but may also have a structure that prevents dispersion of a light source inside the sealing unit 121 to prevent energy loss due to dispersion of the infrared laser.

[0046] In addition, the lens unit 122 is attached to one surface of the sealing unit 121 and serves to widen the irradiation range of the infrared laser emitted from the light source unit 110 while focusing the light incident on the sealing unit 121.

[0047] For this purpose, the lens unit 122 may be integrally formed with the sealing unit 121 and may be located along the path of the infrared laser between the light source unit 110 and the sealing unit 121. The lens unit 122 may refract and / or reflect the infrared laser emitted from the light source unit 110 and guide it to the sealing unit 121.

[0048] In addition, the lens unit 122 may have a convex surface facing the sealing unit 121, and may preferably include a cylindrical lens with a side surface attached along the sealing unit 121.

[0049] Furthermore, the pressurizing unit 120 may include a first light-transmitting material satisfying the following formula 1 in order to focus the light incident from the light source unit 110 onto the sealing unit 11a of the case and to uniformly focus the light over the entire surface of the sealing unit 11a while minimizing energy loss.

[0050] [Formula 1] 15≦TC 1st / RI 1st ≦35

[0051] In Equation 1, TC1st is the thermal conductivity of the first light-transmitting material (unit: W / m K), RI 1st indicates the refractive index of the first light-transmitting material for light having a wavelength of 980 nm.

[0052] The above formula 1 represents the ratio of the thermal conductivity of the first light-transmitting material to the refractive index for light having a wavelength of 980 nm. The infrared laser focused by the pressing unit 120 is transmitted to the sealing part 11a of the case in the form of thermal energy, and at this time, the energy storage capacity of the first light-transmitting material can be inferred by reflecting the optical refractive index rather than the optical transmittance for the infrared laser. That is, the above formula 1 can indirectly represent the energy storage capacity of the first light-transmitting material for the infrared laser. The pressing unit according to the present invention adjusts the above formula 1 to 15 to 35 (i.e., 15≦TC 1st / RI 1st Specifically, the first light-transmitting material may satisfy the above formula 1 in the range of 15 to 35 (i.e., 15≦TC 1st / RI 1st ≦35), 15-30 (i.e., 15≦TC 1st / RI 1st ≦30), 20~35 (i.e., 20≦TC 1st / RI 1st ≦35), 20-30 (i.e., 20≦TC 1st / RI 1st ≦30), or 20-25 (i.e., 20≦TC 1st / RI 1st ≦25).

[0053] Furthermore, the first light-transmitting material may have a refractive index of 1.45 to 1.9 for light having a wavelength of 980 nm, and specifically may have a refractive index of 1.45 to 1.85, 1.55 to 1.85, 1.65 to 1.85, or 1.75 to 1.85 for light having a wavelength of 980 nm.

[0054] The first light-transmitting material satisfies the condition of Equation 1, thereby minimizing the energy loss of the infrared laser incident from the light source 110 and uniformly applying heat to the sealing portion 11a of the case. Furthermore, the first light-transmitting material can quickly dissipate the residual heat of the sealing portion, thereby forming a uniform sealing thickness of the sealing portion.

[0055] Furthermore, the first light-transmitting material may have a Mohs hardness within a specific range. Specifically, the first light-transmitting material may have a Mohs hardness of 8.0 or greater, more specifically, a Mohs hardness of 8.5 or greater, or 9.0 or greater. By satisfying this Mohs hardness, the first light-transmitting material according to the present invention can be prevented from breaking under heat and pressure conditions, thereby preventing damage to the sealing portion 11a due to breakage of the pressure portion 120 during sealing of the case sealing portion 11a.

[0056] Meanwhile, the pressure applying unit 120 may include a first light-transmitting material, and in some cases, the first light-transmitting material may be included in the sealing unit 121 of the pressure applying unit 120, which requires high thermal energy transfer efficiency and hardness, and the lens unit 122 attached to the sealing unit 121 may include one or more of the first light-transmitting material and the second light-transmitting material.

[0057] Specifically, the lens unit 122 may be made of a first light-transmitting material, and in some cases, since a relatively low thermal conductivity is required compared to the sealing unit 121, it may be made of a second light-transmitting material alone or in combination with it.

[0058] As described above, the lens unit 122 functions to focus light incident through the entire surface of the lens unit 122 onto the sealing unit 121, and therefore may require a relatively high light transmittance but a low thermal conductivity compared to the sealing unit 121. Therefore, the lens unit 122 may include a second light-transmitting material having a relatively low thermal conductivity and optical refractive index compared to the first light-transmitting material, and the second light-transmitting material may satisfy the following formula 2.

[0059] [Formula 2] 0.5≦TC 2nd / RI 2nd ≦2

[0060] In Equation 2, TC 2nd is the thermal conductivity of the second light-transmitting material (unit: W / m K), RI 2nd indicates the refractive index of the second light-transmitting material for light having a wavelength of 980 nm.

[0061] Equation 2 above represents the ratio of the thermal conductivity of the second light-transmitting material to the refractive index for light having a wavelength of 980 nm. The infrared laser focused by the pressure applying unit 120 is transmitted to the sealed portion 11a of the case in the form of thermal energy. The energy storage capacity of the second light-transmitting material can be inferred by reflecting the optical refractive index rather than the optical transmittance for the transmitted infrared laser. That is, Equation 2 above can indirectly represent the energy storage capacity of the second light-transmitting material for the infrared laser.

[0062] The pressure applying unit according to the present invention is configured to set the above formula 2 to 0.5 to 2 (i.e., 0.5≦TC 2nd / RI 2nd ≦2), specifically, the second light-transmitting material may contain a second light-transmitting material that satisfies the above formula 2 in the range of 0.5 to 1.9 (i.e., 0.5≦TC 2nd / RI 2nd ≦1.9), 0.5~1.75 (i.e., 0.5≦TC 2nd / RI 2nd ≦1.75), 0.5~1.5 (i.e., 0.5≦TC 2nd / RI 2nd ≦1.5), or 0.5 to 1.35 (i.e., 0.5≦TC 2nd / RI 2nd ≦1.35)。

[0063] Furthermore, the second light-transmitting material may have a refractive index of 1.40 to 1.60 for light having a wavelength of 980 nm, specifically, 1.45 to 1.60, 1.45 to 1.55, or 1.50 to 1.55 for light having a wavelength of 980 nm. By satisfying the condition of Equation 2, the second light-transmitting material can focus the infrared laser incident from the light source unit 110 onto the sealing unit 121 while minimizing energy loss.

[0064] Furthermore, when the lens unit 122 includes a first light-transmitting material and a second light-transmitting material, the lens unit 122 may include a first light-transmitting material 1st and a second light-transmitting material 2nd to be symmetrical with respect to a center line C including the center of the cross section. In this case, the center line C may be parallel to the pressing direction of the sealing unit 121 and may include the center of the sealing unit 121.

[0065] As one example, the lens unit 122 may be composed of only the second light-transmitting material 2nd as shown in (a) of Figure 2, and the first light-transmitting material 1st and the second light-transmitting material 2nd may be arranged symmetrically with respect to the center line C as shown in (b) to (d) of Figure 2.

[0066] In the present invention, the cross-sectional structures of the first light-transmitting material 1st and the second light-transmitting material 2nd that make up the lens unit 122 are configured symmetrically with respect to the center line C of the lens unit 122, thereby maximizing the thermal energy of the infrared laser focused on the sealing unit 121 and improving the processability and economy of the lens unit 122 compared to when the lens unit 122 is configured solely with the first light-transmitting material 1st, which has high hardness. In addition, since the amount of energy focused on the sealing unit 121 can be adjusted depending on the cross-sectional structures of the first light-transmitting material 1st and the second light-transmitting material 2nd, there is an advantage that it can be selectively applied depending on the type and size of the case used in manufacturing a secondary battery.

[0067] Meanwhile, the first light-transmitting material and the second light-transmitting material may be applied without any particular limitation as long as they respectively satisfy the conditions of the above-mentioned formulas 1 and 2. Specifically, germanium, silicone, zinc sulfide, magnesium fluoride, sapphire, glass, quartz, etc. may be applied as the first light-transmitting material and the second light-transmitting material.

[0068] As one example, the first light-transmitting material may include sapphire (TC / RI: 22.2 to 25.7, refractive index: 1.75 to 1.8, Mohs hardness: 9), and the second light-transmitting material may include quartz (TC / RI: 0.65 to 1.33, refractive index: 1.5 to 1.55, Mohs hardness: 6).

[0069] The sealing device for a pouch-type secondary battery according to the present invention has the above-described configuration, and therefore can uniformly heat and seal the sealing portion of the case, and can prevent damage to the sealing unit that is heated to a high temperature during sealing. This can improve the quality of the secondary battery, and at the same time, improve processability and economy.

[0070] <Manufacturing method of pouch-type secondary battery> In one embodiment, the present invention further comprises: A method for manufacturing a secondary battery using the above-described pouch-type secondary battery sealing device is provided.

[0071] The method for manufacturing a secondary battery according to the present invention has the advantage that the quality of the manufactured secondary battery is improved because the sealing device according to the present invention described above can be used during sealing to achieve uniform and tight sealing of the sealed portion.

[0072] In this case, the manufacturing method includes the steps of: accommodating an electrode assembly and an electrolyte in a pouch-shaped case made of a laminate sheet including a metal layer and an inner sealant layer, the pouch-shaped case including an electrode assembly accommodation portion and a sealing portion surrounding the electrode assembly accommodation portion; disposing the sealing device of the present invention at one or more positions above and below the sealing portion of the pouch-shaped case; and applying pressure to the sealing portion of the pouch-shaped case while irradiating light from a light source unit of the sealing device to a pressure unit, thereby sealing the pouch-shaped case.

[0073] First, the step of housing the electrode assembly and the electrolyte in the pouch-type case may be performed in a manner commonly used in the art.

[0074] In this case, the electrode assembly may be any one of a jelly roll type electrode assembly in which one or more negative electrodes, separators, and positive electrodes are sequentially stacked and wound up; a stack and folding type electrode assembly in which unit cells in which a negative electrode, separator, and positive electrode are sequentially stacked are disposed on a long film-like separator and then wound up in a single direction; and a stack and folding type electrode assembly in which unit cells in which a negative electrode, separator, and positive electrode are sequentially stacked are disposed on a long film-like separator and then wound up in a zigzag direction.

[0075] The pouch-shaped case may be made of a laminate sheet including a metal layer including an aluminum layer and an inner sealant layer.

[0076] The metal layer serves to prevent air, moisture, etc. from entering the battery. The material used for the metal layer is not particularly limited as long as it has excellent formability and ductility and can be heated by infrared rays. For example, the metal layer may be made of aluminum or an aluminum alloy.

[0077] The inner sealant layer is heat-sealed to the electrode assembly by heat and pressure applied to the inner sealant layer, and is typically made of a non-oriented polypropylene (CPP) film. An adhesive layer may be added between the outer resin layer and the metal layer and / or between the metal layer and the inner sealant layer to compensate for the weak adhesive strength between the layers on both sides of the adhesive layer.

[0078] In addition, the step of disposing the sealing device of the present invention on the sealed portion of the pouch-type case is performed by disposing the sealing device of the present invention on the upper and / or lower portions of the sealed portion of the pouch-type case after the electrode assembly and the electrolyte are housed in the pouch-type case.

[0079] As an example, the above step can be performed by disposing sealing devices at the top and bottom of the sealed portion of the pouch-type case.

[0080] In addition, the step of pressurizing and sealing the sealing portion of the pouch-type case is a step of sealing the sealing portion, in which light irradiation from a light source unit of a sealing device arranged on the sealing portion to the pressurizing portion and pressurizing the sealing portion of the pouch-type case can be performed simultaneously, and in some cases, light irradiation to the pressurizing portion can be performed after pressurizing the sealing portion of the pouch-type case.

[0081] In this case, the light source unit may emit an infrared laser to the pressure applying unit, and the infrared laser may have a wavelength of 750 nm to 1,000 nm or 800 nm to 980 nm. If the wavelength of the infrared laser is too long, it may not be sufficient to induce heat generation in the metal barrier layer or melting of the sealant layer, or it may take a long time. Conversely, if the wavelength is too short, it may be undesirable because the high energy may cause the battery case to burst or a fire may occur.

[0082] The temperature at which the sealant layer melts upon irradiation with the infrared laser may be 180 to 300° C. Temperatures outside this range are not preferred because they may result in insufficient or excessive melting, making it difficult to form a substantially uniform sealed portion.

[0083] The pressure applied to the sealed portion of the case by the pressure unit of the sealing device is preferably in the range of 0.1 to 5 MPa. The pressure applied to the sealed portion of the case can be adjusted so that it is uniform across the entire surface of the sealed portion using a pressure gauge (not shown) provided in the sealing device.

[0084] The present invention will be described in more detail below with reference to examples and experimental examples.

[0085] However, the following examples and experimental examples are merely illustrative of the present invention, and the content of the present invention is not limited to the following examples and experimental examples.

[0086] <Examples and Comparative Examples> The electrode assembly and electrolyte were inserted into the pouch-shaped case, and the unsealed pouch cell containing the electrode assembly and electrolyte was fixed to a sealing device. The sealing device used had the structure shown in Figure 1. Then, an infrared laser with a wavelength of 980 nm was irradiated onto the lens unit of the pressure applying section using an infrared diode in the light source section (output: 80-85 W / cm). 2 ) while the sealing unit of the pressure section was used to pressurize the sealed portion of the pouch case at 2 MPa to seal the sealed portion.

[0087] The sealing unit of the pressure applying part was made of a first light transmitting material, and the lens unit of the pressure applying part was made of at least one of the first light transmitting material and the second light transmitting material. The physical properties of the first light transmitting material and the second light transmitting material and the cross-sectional structure of the lens unit were adjusted as shown in Table 1 below.

[0088] [Table 1]

[0089] <Experimental Example> In order to confirm the performance of the sealing device according to the present invention, the sealing quality of the sealed portion of the pouch-type secondary batteries sealed in the examples and comparative examples was evaluated.

[0090] Specifically, to check whether the case seal was uniform and tight, the thickness was measured at 10 random points on the seal. The average value was calculated from the measured values, and the error rate of the point with the largest error was calculated based on the calculated average value. The results are shown in Table 2 below.

[0091] [Table 2]

[0092] As shown in Table 2 above, it can be seen that the sealing device for a pouch-type secondary battery according to the present invention can seal the sealed portion of the case uniformly and safely.

[0093] Specifically, it was confirmed that the secondary battery of the embodiment, which used a sealing device in which a light-transmitting material satisfying the conditions of Equation 1 was applied to the sealing unit of the pressure applying part, had a uniformly sealed sealing part and the maximum error rate based on the average thickness of the sealing part was less than 5%.

[0094] However, in the secondary battery of the comparative example, in which a sealing device using a light-transmitting material that does not satisfy Equation 1 was used, the sealing part was sealed unevenly, and the maximum error rate based on the average thickness of the sealing part was found to be 10% or more.

[0095] From these results, it can be seen that the sealing device according to the present invention and the method for manufacturing a secondary battery using the same can not only uniformly seal the sealed portion of the case, but also prevent damage to the sealing unit that is heated to a high temperature during sealing, thereby improving the quality of the secondary battery and at the same time improving processability and economy.

[0096] Although the present invention has been described above with reference to preferred embodiments, it will be understood that a person skilled in the art or having ordinary knowledge in the art can make various modifications and changes to the present invention without departing from the spirit and technical scope of the present invention as set forth in the claims below.

[0097] Therefore, the technical scope of the present invention is not limited to the content described in the Summary of the Invention of the specification, but is defined by the claims. [Explanation of symbols]

[0098] 10: Pouch-type secondary battery 11: Pouch-type case 11a: Case sealing part 12: Electrode lead 100: Sealing device 110: Light source section 120: Pressure section 121: Ceiling unit 122: Lens unit

Claims

1. a pressure applying part located at least at one of the upper and lower parts of the sealed part of the pouch case and made of a material that transmits light; a light source unit that irradiates the pressure applying unit with light, The pressure applying unit includes a first light transmitting material that satisfies the following formula 1: [Formula 1] 15≦TC １ｓｔ / RI １ｓｔ ≦35 In Formula 1, T.C. １ｓｔ represents the thermal conductivity (unit: W / m K) of the first light transmitting material, RI １ｓｔ represents the refractive index of the first light-transmitting material for light having a wavelength of 980 nm, the pressurizing unit includes a sealing unit that contacts a sealed portion of the pouch case to apply heat and pressure, and a lens unit that is positioned between the light source unit and the sealing unit and focuses light irradiated from the light source unit onto the sealing unit, the lens unit includes the first light-transmitting material and the second light-transmitting material; The sealing device for a pouch-type secondary battery, wherein the first light-transmitting material and the second light-transmitting material have a symmetrical structure with respect to a center line including a cross-sectional center of the lens unit.

2. 2. The sealing device for a pouch-type secondary battery according to claim 1, wherein the first light-transmitting material has a refractive index of 1.45 to 1.9 for light having a wavelength of 980 nm.

3. The sealing device for a pouch-type secondary battery according to claim 1 , wherein the first light-transmitting material exhibits a Mohs hardness of 8.0 or more.

4. A sealing device for a pouch-type secondary battery as described in claim 1, wherein the sealing unit includes the first light-transmitting material.

5. The second light-transmitting material satisfies formula 2, [Formula 2] 0.5≦TC ２ｎｄ / RI ２ｎｄ ≦2 In Equation 2, T.C. ２ｎｄ represents the thermal conductivity (unit: W / m K) of the second light transmitting material, RI ２ｎｄ The sealing device for a pouch-type secondary battery according to claim 4 , wherein represents the refractive index of the second light-transmitting material with respect to light having a wavelength of 980 nm.

6. 6. The sealing device for a pouch-type secondary battery according to claim 5, wherein the second light-transmitting material has a refractive index of 1.40 to 1.60 for light having a wavelength of 980 nm.

7. The sealing device for a pouch-type secondary battery according to claim 1 , wherein the lens unit is a cylindrical lens.

8. The sealing device for a pouch-type secondary battery according to claim 1, wherein the light source unit irradiates light having a wavelength of 750 nm to 1,000 nm.

9. housing the electrode assembly and the electrolyte in a pouch-type case made of a laminate sheet including a metal layer and an inner sealant layer, the pouch-type case including an electrode assembly housing portion and a sealing portion surrounding the electrode assembly housing portion; disposing the pouch-type secondary battery sealing device according to any one of claims 1 to 8 at one or more points of an upper portion and a lower portion of a sealing portion of the pouch-type case; and pressing the sealing portion of the pouch-type case while irradiating light from the light source unit of the sealing device to the pressing portion to seal the pouch-type case.

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