Pouch-type battery and sealing device for pouch-type battery

Abstract

The present technology relates to a pouch-type battery and a sealing device for a pouch-type battery, in which safety is prevented from being reduced due to a decrease in the thickness of a lower pouch during a sealing process by heat melting.

Description

[0001] Cross-reference to related applications

[0002] This application claims priority based on Korean Patent Application No. 10-2021-0167905, filed on November 30, 2021, the entire contents of which are incorporated herein by reference. Technical Field

[0003] This invention relates to a pouch-type battery and a sealing device for the pouch-type battery, preventing a decrease in the thickness of the lower pouch during the sealing process via heat fusion, which would reduce safety. Background Technology

[0004] With the development of technology and the increasing demand for mobile devices, the demand for secondary batteries as an alternative to fossil fuels is also increasing rapidly. Therefore, a lot of research has been conducted on secondary batteries that can meet various needs.

[0005] When considering the shape of the battery casing, secondary batteries can be representatively categorized into cylindrical batteries (with electrode assemblies embedded in a cylindrical metal can), prismatic batteries (with electrode assemblies embedded in a prismatic metal can), and pouch batteries (with electrode assemblies embedded in an aluminum laminate pouch-type casing). Furthermore, in terms of materials, there is significant demand for lithium-ion batteries and lithium-ion polymer batteries, which excel in high energy density, discharge voltage, and output stability.

[0006] Among them, pouch batteries are in high demand because they can be relatively thin and are easy to laminate and arrange, and their shape can be partially deformed. Pouch batteries have a structure in which electrode components and electrolytes are embedded in a pouch-shaped laminate that can accommodate the electrode components, and the resin layer of the laminate can be melted by heating.

[0007] The pouch battery undergoes a heat-sealing process, in which heat and pressure are applied to vertically overlapping laminates along the circumference of the battery casing to achieve a seal, preventing the electrode assembly from being exposed and the electrolyte from leaking. Furthermore, electrode leads extend outwards from the battery casing. A lead film, made of insulating resin, is attached to the surface of the electrode leads and heat-sealed to the laminates, i.e., the pouch, further strengthening the seal around the electrode leads.

[0008] However, when the bags are heat-sealed, a difference in thickness often occurs between the two bags surrounding the electrode assembly and electrode leads after heat sealing. To seal the electrode leads and bags, a pair of upper and lower sealing blocks are used to apply heat and pressure. During the sealing process, after the lower sealing block rises to support the lower bag and electrode leads, the upper sealing block descends to apply heat and pressure. Therefore, because more heat is applied to the lower bag and electrode leads, the resin layer thickness of the lower bag is less than that of the upper bag.

[0009] The relatively thinner lower pouch is susceptible to internal or external pressure. For example, when a pressure less than the specified durability limit is applied to a pouch battery, the upper pouch withstands the pressure, but the lower pouch ruptures, or the resin layer of the lower pouch is stretched and ruptured due to the internal pressure exerted by the gas generated inside the pouch, thus causing the seal to open. Summary of the Invention

[0010] [Technical Issues]

[0011] The purpose of this invention is to provide a pouch-type battery and a sealing device for the pouch-type battery to prevent the thickness of the lower pouch from decreasing even after heat-sealing treatment.

[0012] [Technical Solution]

[0013] This invention provides a sealing device for a pouch-type battery. In an embodiment, the sealing device for a pouch-type battery according to the invention includes an upper sealing block having two levels of upper sealing grooves, the two levels of upper sealing grooves including a first upper step forming a bottom surface and a second upper step formed between the first upper step and the surfaces of the two levels of upper sealing grooves; and a lower sealing block having two levels of lower sealing grooves, the two levels of lower sealing grooves including a first lower step forming the bottom surface and a second lower step formed between the first lower step and the surfaces of the two levels of lower sealing grooves. Furthermore, the upper sealing block can contact a first surface of the electrode lead sealing portion of the pouch-type battery, and the lower sealing block can contact a second surface of the electrode lead sealing portion of the pouch-type battery at a position facing the upper sealing block. Additionally, the sealing device for a pouch-type battery according to the invention satisfies the following condition 1.

[0014] (Condition 1)

[0015]

[0016] In condition 1, B1 represents the average depth difference between the first upper step and the second upper step in the upper sealing block, and B2 represents the average depth difference between the first lower step and the second lower step in the lower sealing block.

[0017] In this embodiment, the average depth difference B1 between the first upper step and the second upper step in the upper sealing block can be in the range of 200 μm to 280 μm. Furthermore, the average depth difference B2 between the first lower step and the second lower step in the lower sealing block can be in the range of 220 μm to 320 μm.

[0018] In an implementation, the difference between the average depth A1 of the second upper step and the average depth A2 of the second lower step can be 10 μm or less. More specifically, the difference between the average depth A1 of the second upper step and the average depth A2 of the second lower step can be in the range of 0.1 μm to 10 μm or 0.1 μm to 5 μm. For example, the average depth A1 of the second upper step and the average depth A2 of the second lower step can be substantially the same.

[0019] In a detailed embodiment, the average depth A1 of the second upper step and the average depth A2 of the second lower step can be in the range of 40 μm to 100 μm or in the range of 70 μm to 80 μm.

[0020] In another embodiment, the upper and lower sealing blocks may have a structure that presses and heats the electrode lead seals of the pouch cell from both sides. In this case, for example, the electrode lead seals can be heated at a temperature in the range of 110°C to 200°C.

[0021] Furthermore, the present invention also provides a pouch-type battery manufactured using the aforementioned sealing device. In an embodiment, the pouch-type battery according to the present invention includes an electrode assembly, electrode leads configured to extend from electrode tabs of the electrode assembly, and an upper pouch and a lower pouch for receiving and sealing the electrode assembly. Furthermore, regarding the electrode lead sealing portion, condition 2 is satisfied, and the electrode lead sealing portion has a structure in which the upper and lower pouches surround the electrode assembly on both sides of the upper and lower pouches, such that the electrode leads of the electrode assembly are exposed.

[0022] (Condition 2)

[0023] 1≤T2-T1≤25(μm)

[0024] In condition 2,

[0025] T1 represents the average thickness of the upper pocket formed on the first surface of the electrode lead, and

[0026] T2 represents the average thickness of the lower pocket formed on the second surface of the electrode lead.

[0027] In an embodiment, in the pouch-type battery of the present invention, for the electrode lead sealing portion, the average thickness T1 of the upper pouch formed on the first surface of the electrode lead can be in the range of 80 μm to 90 μm, and the average thickness T2 of the lower pouch formed on the second surface of the electrode lead can be in the range of 91 μm to 105 μm.

[0028] In another embodiment, each of the upper and lower bags may include a first resin layer and a metal layer located on the inner surfaces of the upper and lower bags, and a second resin layer located on the outer surfaces of the upper and lower bags. Furthermore, regarding the electrode lead sealing portion, the thickness ratio of the first resin layer of the upper bag relative to the thickness of the upper bag may be in the range of 10% to 18%. Furthermore, the thickness ratio of the first resin layer of the lower bag relative to the thickness of the lower bag may be in the range of 20% to 30%.

[0029] In a detailed embodiment, for the electrode lead sealing portion, the thickness of the first resin layer of the upper bag can be in the average range of 8 μm to 17 μm, and the thickness of the first resin layer of the lower bag can be in the average range of 20 μm to 30 μm.

[0030] In another embodiment, the pouch-type battery according to the invention may include an unsealed region corresponding to the location of the electrode assembly and not sealed between the upper and lower pouches. In the unsealed region, the thickness of the first resin layer of each of the upper and lower pouches may be in the range of 50 μm to 100 μm on average.

[0031] In a detailed embodiment, in each of the upper and lower bags, the first resin layer may contain polypropylene resin, the metal layer may contain aluminum or aluminum alloy, and the second resin layer may contain polyethylene terephthalate (PET) resin.

[0032] For example, the electrode assembly can be a stacked electrode assembly.

[0033] [Beneficial Effects]

[0034] The sealing device of the pouch-type battery of the present invention, having the above-described structure, prevents the thickness of the lower pouch from decreasing even after heat-sealing treatment. Furthermore, the manufactured pouch-type battery maintains its sealing performance even under high internal and external pressure variations. Attached Figure Description

[0035] Figure 1 This is a schematic diagram illustrating the process of sealing using a sealing device 10 (hereinafter referred to as "sealing device") for a pouch-type battery according to an embodiment of the present invention.

[0036] Figure 2 This is a schematic cross-sectional view showing a sealing device for a pouch-type battery according to an embodiment of the present invention.

[0037] Figure 3 This is a schematic diagram illustrating the process of sealing the electrode lead forming portion of a pouch battery using a sealing device according to an embodiment of the present invention.

[0038] Figure 4 This is a schematic diagram showing a pouch battery 500 sealed by a sealing device according to the invention. Figure 5 yes Figure 4 A partial magnified view of the cross section A-A' of the 500 pouch cell. Detailed Implementation

[0039] The present invention can be modified in different ways and can be implemented in different ways, and therefore specific implementation methods will be described in detail below.

[0040] However, it should be understood that the present invention is not limited to the specific embodiments, but includes all variations, equivalents and alternatives contained in the spirit and scope of the invention.

[0041] It should be understood that in this invention, terms such as “comprising” or “having” are intended to indicate the presence of the features, numbers, steps, operations, components, parts or combinations thereof described in the specification, and do not preclude the possibility of the presence or addition of one or more other features, numbers, steps, operations, components, parts or combinations thereof.

[0042] Furthermore, in this invention, when describing a first component such as a layer, film, region, or plate as being "above" a second component, this includes not only the case where the first component is "directly above" the second component, but also the case where a third component exists between them. Conversely, when describing a first component such as a layer, film, region, or plate as being "below" a second component, this includes not only the case where the first component is "directly below" the second component, but also the case where a third component exists between them. Moreover, in this application, the state of placing a first component "above" a second component can include not only the state of placing the first component above the second component, but also the state of placing the first component below the second component.

[0043] This invention provides a sealing device for a pouch-type battery. In an embodiment, the sealing device for a pouch-type battery according to the invention includes an upper sealing block having two levels of upper sealing grooves, the two levels of upper sealing grooves including a first upper step forming a bottom surface and a second upper step formed between the first upper step and the surfaces of the two levels of upper sealing grooves; and a lower sealing block having two levels of lower sealing grooves, the two levels of lower sealing grooves including a first lower step forming the bottom surface and a second lower step formed between the first lower step and the surfaces of the two levels of lower sealing grooves. Furthermore, the upper sealing block contacts a first surface of the electrode lead sealing portion of the pouch-type battery, and the lower sealing block contacts a second surface of the electrode lead sealing portion of the pouch-type battery at a position facing the upper sealing block.

[0044] In this invention, the electrode lead sealing portion refers to the area where the electrode lead extends from the electrode assembly. Specifically, from a cross-sectional perspective, the electrode lead sealing portion has a structure with protruding lead metal formed of aluminum or copper, and the area of ​​the lead metal sealed by the bag is surrounded by a lead film. The upper bag has a structure surrounding the upper side of the electrode lead, and the lower bag has a structure surrounding the lower side of the electrode lead. In this invention, the first upper step and the first lower step are areas where the upper and lower portions of the lead metal surrounded by the lead film are inserted and sealed. Furthermore, the second upper step and the second lower step are areas where extensions of the lead film are retained on the sides of the lead metal on the upper and lower sides of the second upper step and the second lower step.

[0045] Furthermore, the sealing device of the pouch-type battery according to the present invention satisfies condition 1.

[0046] (Condition 1)

[0047]

[0048] In condition 1, B1 represents the average depth difference between the first upper step and the second upper step in the upper sealing block, and B2 represents the average depth difference between the first lower step and the second lower step in the lower sealing block.

[0049] The sealing device of the pouch battery according to the present invention fixes the space in the lower region, thereby preventing a reduction in the thickness of the lower pouch while sealing the electrode lead sealing portion. Specifically, in the sealing device of the pouch battery, since the first lower step of the lower sealing block is formed relatively deeply, heat and pressure are prevented from concentrating in the lower pouch.

[0050] In this invention, the value of the formula specified in Condition 1 is in the range of 6.5% to 15%, 6.5% to 10%, 7.5% to 15%, 7.5% to 9%, or 8% to 8.5%. Since the value of Condition 1 satisfies the above range, the sealing device of the pouch-type battery according to the invention can minimize the reduction in the thickness of the lower pouch and prevent the upper and lower pouches surrounding the electrode lead sealing portion from widening.

[0051] In this embodiment, the average depth difference B1 between the first upper step and the second upper step in the upper sealing block is in the range of 200 μm to 280 μm. Here, the depth difference between the first upper step and the second upper step refers to, for example, the depth from the bottom surface of the second upper step to the bottom surface of the first upper step. Specifically, the depth difference B1 between the two upper steps ranges from 200 μm to 250 μm, 200 μm to 280 μm, or 220 μm to 250 μm.

[0052] Furthermore, the average depth difference B2 between the first and second lower steps in the lower sealing block is in the range of 220 μm to 320 μm. Here, the depth difference between the first and second lower steps refers to, for example, the depth from the bottom surface of the second lower step to the bottom surface of the first lower step. Specifically, the depth difference B2 between the first and second lower steps ranges from 220 μm to 300 μm, 250 μm to 320 μm, or 250 μm to 280 μm.

[0053] In this invention, the depth of the lower sealing groove formed by the lower bag is greater than the depth of the upper sealing groove formed by the upper bag, relative to the electrode lead sealing portion. Therefore, the reduction in the thickness of the lower bag during the sealing process is minimized. For example, the average depth difference B2 between the first and second lower steps in the lower sealing block is 5 μm to 20 μm greater than the average depth difference B1 between the first and second upper steps in the upper sealing block.

[0054] In one embodiment, the difference between the average depth A1 of the second upper step and the average depth A2 of the second lower step is 10 μm or less. More specifically, the difference between the average depth A1 of the second upper step and the average depth A2 of the second lower step is in the range of 0.1 μm to 10 μm or 0.1 μm to 5 μm. For example, the average depth A1 of the second upper step and the average depth A2 of the second lower step are substantially the same. In a specific embodiment, the average depth A1 of the second upper step and the average depth A2 of the second lower step are in the range of 40 μm to 100 μm or 70 μm to 80 μm.

[0055] In another embodiment, the upper and lower sealing blocks have a structure that presses and heats the electrode lead sealing portion of the pouch cell from both sides of the upper and lower sealing blocks. In this case, the heating temperature is in the average range of 110°C to 200°C. The sealing device for the pouch cell according to the invention is a device for applying heat and pressure to the edge region of the pouch cell to seal the pouch cell. The resin layer located on the inner surface of the upper and lower pouch is partially melted by heating, and the partially melted resin layers of the upper and lower pouch are bonded together by pressing. The heating temperature can be selected according to the type of inner resin layer applied. For example, the inner surface of the upper and lower pouch can be formed of a polypropylene (PP) layer with a melting point in the range of 130°C to 171°C, in which case the heating temperature can be controlled in the range of 120°C to 180°C.

[0056] Furthermore, the present invention also provides a pouch-type battery manufactured using the aforementioned sealing device. In implementation of the pouch-type battery according to the invention, the thickness of the lower pouch is at a predetermined level or higher relative to the electrode lead sealing portion. In an embodiment, the pouch-type battery according to the invention includes an electrode assembly, electrode leads configured to extend from electrode tabs of the electrode assembly, and an upper pouch and a lower pouch for housing and sealing the electrode assembly. Furthermore, the pouch-type battery according to the invention satisfies condition 2 regarding the electrode lead sealing portion, which is a structure in which the upper and lower pouches surround the electrode assembly on both sides of the upper and lower pouches, exposing the electrode leads of the electrode assembly.

[0057] (Condition 2)

[0058] 1≤T2-T1≤25(μm)

[0059] In condition 2, T1 represents the average thickness of the upper pocket formed on the first surface of the electrode lead, and T2 represents the average thickness of the lower pocket formed on the second surface of the electrode lead.

[0060] In this invention, "bag" refers to the battery casing material surrounding the battery. A pouch-type battery includes a structure where the upper and lower surfaces of the electrode assembly are covered by a bag, and the edges of the upper and lower surfaces are sealed. In the sealing process, reducing the thickness of the lower bag can cause product defects. In the pouch-type battery according to the invention, the reduction in the thickness of the lower bag is minimized relative to the electrode lead sealing portion.

[0061] In a specific embodiment, the average thickness T1 of the upper pouch formed on the first surface of the electrode lead is in the range of 80 μm to 90 μm, and the average thickness T2 of the lower pouch formed on the second surface of the electrode lead is in the range of 91 μm to 105 μm. More specifically, the average thickness T1 of the upper pouch formed on the first surface of the electrode lead is in the range of 83 μm to 88 μm, and the average thickness T2 of the lower pouch formed on the second surface of the electrode lead is in the range of 94 μm to 100 μm.

[0062] Specifically, the thickness difference T2-T1 defined in condition 2 is in the range of 1μm to 25μm, 5μm to 20μm, 6μm to 17μm, and 8μm to 12μm.

[0063] The pouch-type battery according to the present invention has a structure in which the lower pouch is thicker than the upper pouch relative to the electrode lead sealing portion. Generally, during the sealing process, heat and pressure are concentrated on the lower pouch, causing its thickness to tend to be relatively small. However, in the present invention, by applying the sealing device described above, the average thickness of the lower pouch is more than 1 μm thicker than the upper pouch, particularly more than 6 μm thicker. When an external force is applied to the pouch-type battery or the internal pressure of the pouch-type battery increases, the electrode lead sealing portion bursts, particularly a portion of the lower pouch of the electrode lead sealing portion widens first. In the present invention, the residual rate of the lower pouch in the electrode lead sealing portion of the pouch-type battery can be improved, thereby improving the sealability of the battery.

[0064] The bag has a structure comprising, for example, a first resin layer and a metal layer located on the inner surface of the bag, and a second resin layer located on the outer surface of the bag. During the sealing process, the thickness of the first resin layer on the inner surface varies considerably, while the thicknesses of the metal layer and the second resin layer remain almost unchanged. For example, during the sealing process, the thickness of the first resin layer is greatly reduced, while the thicknesses of the metal layer and the second resin layer remain constant. Specifically, unlike the upper bag, in the lower bag, the thickness of the first resin layer is greatly reduced, resulting in poor sealing and making the seal prone to rupture under increased internal and external pressure.

[0065] In embodiments, each of the upper and lower bags according to the invention includes a first resin layer, a metal layer, and a second resin layer located on the inner surfaces of the upper and lower bags, respectively. Furthermore, regarding the electrode lead sealing portion, the ratio of the thickness of the first resin layer of the upper bag to the thickness of the upper bag is in the range of 10% to 18%, and the ratio of the thickness of the first resin layer of the lower bag to the thickness of the lower bag is in the range of 20% to 30%. More specifically, in the present invention, the ratio of the thickness of the first resin layer of the upper bag to the thickness of the upper bag is in the range of 13% to 17%, and the ratio of the thickness of the first resin layer of the lower bag to the thickness of the lower bag is in the range of 22% to 28%.

[0066] In this invention, the first resin layer in the lower bag is thicker than the electrode lead sealing portion. In the bag lamination structure, the first resin layer is the layer that provides adhesion during the sealing process. Because the first resin layer in the lower bag is thicker, the adhesion to the electrode leads can be increased, and excellent durability can be achieved even under high pressure.

[0067] In a specific example, for the electrode lead sealing portion, the thickness of the first resin layer in the upper bag averages between 8 μm and 17 μm, particularly between 10 μm and 15 μm. Furthermore, for the electrode lead sealing portion, the thickness of the first resin layer in the lower bag averages between 20 μm and 30 μm, particularly between 22 μm and 26 μm.

[0068] In another embodiment, the pouch-type battery according to the invention includes a non-sealed region corresponding to the location of the electrode assembly, and is not sealed between the upper and lower pouches. Accordingly, the portion where the upper and lower pouches are bonded together by means of heat fusion or the like is called the sealed region. In the non-sealed region, the thickness of the first resin layer of the upper and lower pouches is on average in the range of 50 μm to 100 μm.

[0069] The bag has a structure comprising, for example, a first resin layer and a metal layer located on the inner surface of the bag, and a second resin layer located on the outer surface of the bag. For example, in the upper and lower bags, the first resin layer contains PP resin, and the metal layer contains aluminum or an alloy thereof. Furthermore, the second resin layer comprises polyethylene terephthalate (PET) resin, and in some cases, it may have a two-layer structure, including a nylon layer and a PET layer formed thereon. Additionally, the thickness of the bag may vary depending on the product or standard, but is on average in the range of 120 μm to 200 μm. Furthermore, relative to the bag before the sealing process, the thickness of the first resin layer in the bag is on average in the range of 50 μm to 100 μm.

[0070] During the sealing process, the thickness of the first resin layer on the inner surface varies significantly, while the thickness of the metal layer and the second resin layer remains almost unchanged. Specifically, the PP resin forming the first resin layer has a relatively low melting point. Therefore, when heat is applied for sealing, the surface portion of the first resin layer melts and is thermally fused into the facing layer. However, in addition to heating, pressure is applied during the sealing process, resulting in a significant reduction in the thickness of the first resin layer. This reduction in the thickness of the first resin layer leads to sealing defects, and the seal is prone to bursting when internal pressure increases.

[0071] In embodiments, the electrode assembly according to the invention is a stacked electrode assembly. The stacked electrode assembly includes a structure in which cell units, comprising a positive electrode, a separator, and a negative electrode, are repeatedly stacked. The positive and negative electrodes include all cases where active material is formed on one or both surfaces of the current collector. The number of times the cell units are repeated is, for example, in the range of 20 to 80 times, and can be varied according to product specifications or desired specifications. In the pouch cell according to the invention, the form of the electrode assembly does not exclude cylindrical structures and jelly roll structures, but a stacked electrode assembly can be applied more effectively.

[0072] [Detailed Description of Preferred Embodiments]

[0073] The specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings, but the scope of the present invention is not limited thereto.

[0074] (First Implementation)

[0075] Figure 1It is a schematic diagram showing the process of sealing using a sealing device 10 (hereinafter referred to as "sealing device") of a pouch-type battery according to an embodiment of the present invention. Refer to Figure 1 , the sealing device 10 of the present invention has a structure in which an upper sealing block 100 and a lower sealing block 200 apply pressure and heat for sealing in a state where an upper pouch 400 and a lower pouch 401 are respectively arranged above and below an electrode lead 300. The electrode lead 300 has a structure made of aluminum, and the outer peripheral surface of the electrode lead 300 is surrounded by a lead film 310. In addition, the sealing device 10 includes an upper sealing block 100 and a lower sealing block 200, and has a structure with two-stage formed sealing grooves 130 and 230.

[0076] In the present invention, the two-stage lower sealing groove 230 formed in the lower sealing block 200 is relatively deeper than the two-stage upper sealing groove 130 formed in the upper sealing block 100.

[0077] (Second Embodiment)

[0078] Figure 2 It is a schematic cross-sectional view showing a sealing device of a pouch-type battery according to an embodiment of the present invention.

[0079] Refer to Figure 2 , the sealing device 10 includes an upper sealing block 100 and a lower sealing block 200. Two-stage upper sealing grooves 130 and two-stage lower sealing grooves 230 are formed in the upper sealing block 100 and the lower sealing block 200.

[0080] The upper sealing block 100 is provided with two-stage upper sealing grooves 130, which include a first upper step 110 forming the bottom surface and a second upper step 120 formed between the first upper step 110 and the surface of the two-stage upper sealing groove 130. Here, with respect to the bottom surface and the surface, the bottom surface means the lowermost surface with respect to the direction of observing the two-stage upper sealing groove 130 inward, and the surface means the uppermost surface.

[0081] The lower sealing block 200 is provided with two-stage lower sealing grooves 230 formed. The two-stage lower sealing grooves 230 include a first lower step 210 forming the bottom surface and a second lower step 220 formed between the first lower step 210 and the surface of the two-stage lower sealing groove 230.

[0082] In the sealing device 10, the two-stage upper sealing grooves 130 formed in the upper sealing block 100 and the two-stage lower sealing grooves 230 formed in the lower sealing block 200 have different step heights. Specifically, the height A2 of the first lower step is greater than the height A1 of the first upper step (A1 < A2). In addition, the height B1 of the second upper step and the height B2 of the second lower step are substantially equal to each other, and the difference between the two is 10 μm or less.

[0083] For example, in the sealing device 10, the height A1 of the first upper step formed in the upper sealing block 100 is 240 μm, and the height B1 of the second upper step is 76 μm. The height A2 of the first lower step formed in the lower sealing block 200 is 260 μm, and the height B2 of the second lower step is 76 μm. This configuration differs from sealing devices in the related art where the upper and lower sealing blocks are symmetrical. For example, in sealing devices according to the related art, the heights of the first upper step and the first lower step are controlled to be equal at a level of 250 μm. The difference of the present invention is that the height A1 of the first upper step is reduced, and the height A2 of the first lower step is increased.

[0084] (Third Implementation)

[0085] Figure 3 This is a schematic diagram illustrating the process of sealing the electrode lead forming portion of a pouch battery using a sealing device according to an embodiment of the present invention.

[0086] See Figure 3 The first upper step 110 of the upper sealing block 100 corresponds to the upper portion of the electrode lead 300 surrounded by the lead film 310. Furthermore, the second upper step 120 extends laterally from the electrode lead 300 and corresponds to the upper portion of the remaining lead film 310. Similarly, the first lower step 210 of the lower sealing block 200 corresponds to the lower portion of the electrode lead 300 surrounded by the lead film 310, and the second lower step 220 extends laterally from the electrode lead 300 and corresponds to the lower portion of the remaining lead film 310.

[0087] While being heated by built-in heating coils, the upper sealing block 100 and the lower sealing block 200 apply pressure to the electrode lead 300 positioned between the upper bag 400 and the lower bag 401. The upper bag 400 and the lower bag 401 have a structure in which an aluminum layer, a nylon resin layer, and a PET resin layer are laminated onto a PP resin layer located within the upper bag 400 and the lower bag 401. The heating temperature of the upper sealing block 100 and the lower sealing block 200 is approximately 150°C to 180°C, and the PP resin portion forming the inner surface of the bag partially melts and heat-melts to achieve adhesion.

[0088] (Fourth Implementation)

[0089] Figure 4 This is a schematic diagram showing a pouch battery 500 sealed by a sealing device according to the invention. Figure 5 yes Figure 4 A partial magnified view of the cross section A-A' of the 500 pouch cell.

[0090] See Figure 4The pouch battery 500 has a structure in which a pouch battery housing 440 surrounds an electrode assembly housed therein and electrode leads 300 extending outward from the electrode tabs. A lead film 310 is located between the electrode leads 300 and the pouch battery housing 440. The pouch battery housing 440 includes an upper pouch 400 and a lower pouch 401, and the edges of the upper pouch 400 and the lower pouch 401 are sealed.

[0091] Figure 5 A cross-section of the sealed region of the electrode lead 300 is shown. The upper bag 400 and the lower bag 401 each have a three-layer structure, including first resin layers 410 and 411 formed in the upper bag 400 and the lower bag 401 respectively, aluminum layers 420 and 421, and second resin layers 430 and 431 formed on the exterior. Furthermore, the electrode lead 300 has a structure surrounded by a lead film 310.

[0092] In this invention, battery safety is maximized by minimizing the reduction in the thickness of the first resin layer 411 in the lower bag 401.

[0093] The invention will now be described in more detail by way of examples and the like.

[0094] Example

[0095] use Figure 2 The sealing device shown seals the pouch cell. The sealing is performed relative to the area where the electrode leads are formed. During the sealing process, the heating temperature is 180°C. Detailed specifications of the sealing device are shown in Table 1 below.

[0096] Furthermore, the bag used in the pouch-type battery has a three-layer structure, including a PP resin layer, an aluminum layer, and a PET layer. The total thickness of the bag is 155 μm, and the thickness of the PP resin layer is 80 μm.

[0097] Comparative example

[0098] The sealing method for pouch batteries is the same as in the example, except that the specifications of the sealing device are changed as shown in Table 1 below.

[0099] (Table 1)

[0100]

[0101] Experimental Example 1: Evaluation of PP Residual Rate in Bags

[0102] For the sealed pouch cells in the example and comparative examples, the residual PP resin layer was evaluated. The PP residual rate (%) was calculated by comparing the thickness of the PP resin layer before sealing with the thickness of the PP resin layer after sealing.

[0103] (Table 2)

[0104]

[0105]

[0106] As shown in Table 2, in the comparative example, the heat and pressure during the sealing process are concentrated on the lower bag, so the PP residue rate in the lower bag is only 13%.

[0107] In contrast, in the pouch battery described according to the embodiment, the PP residual rate in the lower pouch reaches 30%. When the pouch ruptures due to applied external force or increased internal pressure, the lower pouch is first widened between the electrode lead seals. This invention improves the safety of the pouch battery by maximizing the PP residual rate in the lower pouch within the electrode lead seals.

[0108] Furthermore, in the example, the PP residue rate in the upper bag was found to be as low as 16%. The upper bag was more securely heat-sealed in the electrode lead sealing section, thereby reducing the PP residue rate in the upper bag.

[0109] Experimental Example

[0110] The sealing strength and withstand voltage of the sealed pouch cells in the example and comparative examples were evaluated. The evaluation results are shown in Table 3 below.

[0111] Sealing strength evaluation Apply a vertical force at room temperature and measure the force at the point of damage to the electrode lead seal.

[0112] Compressive strength The withstand pressure was measured at 60°C, especially when a hole was formed on one side of a sealed pouch cell and inert gas (Ar) was injected, and the pressure was measured at the point of damage to the electrode lead seal.

[0113] (Table 3)

[0114] category Example Comparative example Sealing strength evaluation (N) 100.9 63.7 Compressive strength evaluation (atm) 10.1 9.5

[0115] As shown in Table 3, the sealing strength and pressure resistance of the pouch battery according to the embodiment are significantly improved compared with the comparative example.

[0116] The present invention has been described in more detail above with reference to the accompanying drawings and embodiments. However, since the configurations described in the drawings or the embodiments described in this specification are merely embodiments of the present invention and do not represent the full technical essence of the present invention, it should be understood that various equivalent methods and variations that can replace these configurations exist at the time of filing this application.

[0117] [Explanation of Labels in the Attached Image]

[0118] 10: Sealing device 100: Upper sealing block

[0119] 110: First step up 120: Second step up

[0120] 130: Upper sealing groove; 200: Lower sealing block

[0121] 210: First step down two levels 220: Second step down

[0122] 230: Two-stage lower sealing groove; 240: Insulating film.

[0123] 300: Electrode lead; 310: Lead film

[0124] 400: upper bag 401: lower bag

[0125] 410, 411: First resin layer; 420, 421: Aluminum layer

[0126] 430, 431: Second resin layer; 440: Pouch-type battery casing

[0127] 500: Pouch battery

[0128] A1: Height of the first step B1: Height of the second step

[0129] A2: Height of the first step down B2: Height of the second step down

Claims

1. A sealing device for a pouch-type battery, the sealing device comprising: The invention includes an upper sealing block having two-stage upper sealing grooves, the two-stage upper sealing grooves including a first upper step forming a bottom surface and a second upper step formed between the first upper step and the surfaces of the two-stage upper sealing grooves; as well as A lower sealing block having a two-stage lower sealing groove, the two-stage lower sealing groove including a first lower step forming the bottom surface and a second lower step formed between the first lower step and the surfaces of the two-stage lower sealing groove; The upper sealing block contacts a first surface of the electrode lead sealing portion of the pouch cell, and the lower sealing block contacts a second surface of the electrode lead sealing portion of the pouch cell at a position facing the upper sealing block. Condition 1 is satisfied, and (Condition 1) In condition 1, B1 represents the average depth difference between the first upper step and the second upper step in the upper sealing block, and B2 represents the average depth difference between the first lower step and the second lower step in the lower sealing block.

2. The sealing device according to claim 1, wherein the average depth difference B1 between the first upper step and the second upper step in the upper sealing block is in the range of 200 μm to 280 μm, and The average depth difference B2 between the first lower step and the second lower step in the lower sealing block is in the range of 220 μm to 320 μm.

3. The sealing device according to claim 1, wherein the difference between the average depth A1 of the second upper step and the average depth A2 of the second lower step is 10 μm or less.

4. The sealing device according to claim 3, wherein the average depth A1 of the second upper step and the average depth A2 of the second lower step are in the range of 40 μm to 100 μm.

5. The sealing device according to claim 1, wherein the upper sealing block and the lower sealing block have a structure that presses and heats the electrode lead sealing portion of the pouch cell from both sides of the upper sealing block and the lower sealing block, and The electrode lead sealing portion is heated at a temperature ranging from 110°C to 200°C.

6. A pouch-type battery, comprising: Electrode assembly; Electrode leads configured to extend from the electrode tabs of the electrode assembly; as well as The upper and lower bags contain and seal the electrode assembly. Regarding the electrode lead sealing portion, condition 2 is satisfied, and the electrode lead sealing portion has the following structure: the upper bag and the lower bag surround the electrode assembly on both surfaces of the upper bag and the lower bag, such that the electrode leads of the electrode assembly are exposed. (Condition 2) 1≤T2-T1≤25 μm In condition 2, T1 represents the average thickness of the upper bag formed on the first surface of the electrode lead, and T2 represents the average thickness of the lower pocket formed on the second surface of the electrode lead. Specifically, the electrode lead sealing portion... The average thickness T1 of the upper bag formed on the first surface of the electrode lead is in the range of 80 μm to 90 μm, and the average thickness T2 of the lower bag formed on the second surface of the electrode lead is in the range of 91 μm to 105 μm.

7. The pouch-type battery of claim 6, wherein each of the upper pouch and the lower pouch comprises a first resin layer, a metal layer, and a second resin layer located on the inner surfaces of the upper pouch and the lower pouch, and a metal layer located on the outer surfaces of the upper pouch and the lower pouch. Regarding the electrode lead sealing portion... The thickness ratio of the first resin layer of the upper bag to the thickness of the upper bag is in the range of 10% to 18%. The thickness ratio of the first resin layer of the lower bag to the thickness of the lower bag is in the range of 20% to 30%.

8. The pouch cell according to claim 7, wherein the electrode lead sealing portion, The thickness of the first resin layer of the upper bag is on average in the range of 8 μm to 17 μm, and The thickness of the first resin layer in the lower bag is on average in the range of 20 μm to 30 μm.

9. The pouch-type battery of claim 7, wherein the pouch-type battery includes a non-sealed region corresponding to a location accommodating the electrode assembly and is not sealed between the upper pouch and the lower pouch, and In the unsealed area, the thickness of the first resin layer of each of the upper and lower bags is on average in the range of 50 μm to 100 μm.

10. The pouch-type battery according to claim 7, wherein in each of the upper pouch and the lower pouch, The first resin layer contains polypropylene resin. The metal layer contains aluminum or an aluminum alloy, and The second resin layer contains polyethylene terephthalate (PET) resin.

11. The pouch cell of claim 6, wherein the electrode assembly is a stacked electrode assembly.

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