Gas discharge member and secondary battery including same

Abstract

The present invention discloses a gas discharge member that is a gas permeable sheet having holes in a peripheral portion of the sheet, and a secondary battery having the same. The gas discharge member according to an embodiment of the present invention can improve adhesion properties with a case of a secondary battery.

Description

[Technical field]

[0001] The present invention relates to a gas discharge member and a secondary battery including the same.

[0002] This application claims priority to Korean Patent Application No. 10-2022-0054204, filed on May 2, 2022, the entire contents of which are incorporated herein by reference. [Background technology]

[0003] As technological development and demand for mobile devices increases, the demand for secondary batteries as an energy source is rapidly increasing. In particular, secondary batteries are attracting much attention not only for mobile devices such as mobile phones, digital cameras, notebooks, and wearable devices, but also as an energy source for power devices such as electric bicycles, electric cars, and hybrid electric cars.

[0004] Such secondary batteries are classified into cylindrical batteries and prismatic batteries in which the electrode assembly is housed in a cylindrical or prismatic metal can, and pouch-type batteries in which the electrode assembly is housed in a pouch-type case made of an aluminum laminate sheet, according to the shape of the battery case. Here, the electrode assembly housed in the battery case is classified into a jelly roll type in which a separator is interposed between a long sheet-like positive electrode and a negative electrode coated with an active material and wound up as a power generating element having a structure of a positive electrode, a negative electrode, and a separator interposed between the positive electrode and the negative electrode, and a stack type in which a plurality of positive electrodes and a negative electrodes are stacked in sequence with a separator interposed between them.

[0005] Among these, the use of pouch-type batteries, which have a structure in which a stack-type or stack / fold-type electrode assembly is built into a pouch-type battery case made of an aluminum laminate sheet, is gradually increasing due to reasons such as low manufacturing costs, small weight, and easy deformation.

[0006] Meanwhile, in recent years, as the energy density of battery cells increases, there is a problem that the amount of gas generated inside the battery cells also increases. If the gas generated inside the battery cells is not easily discharged, the battery cells may experience a venting phenomenon due to the generation of gas.

[0007] To solve these problems, a secondary battery has been proposed in which an opening is formed in a part of a battery case that penetrates the case in the thickness direction, and a gas exhaust member made of a gas permeable sheet that covers the entire opening is attached to the inside of the opening, so that gas generated inside the battery cell passes through the gas permeable gas exhaust member and is discharged through the opening. If gas generated inside the battery cell passes through the gas permeable gas exhaust member and is smoothly discharged, venting does not occur and the cell can continue to operate.

[0008] If the gas exhaust member and the battery case are not firmly bonded together, the gas exhaust capacity will decrease and moisture from outside the battery cell will penetrate into the battery cell, so it is necessary to improve the adhesive strength of the gas exhaust member to the battery case. Summary of the Invention [Problem to be solved by the invention]

[0009] An object of the present invention is to provide a gas discharge member having improved adhesive strength to a battery case, and a secondary battery including the gas discharge member. [Means for solving the problem]

[0010] In order to solve the above problems, according to one aspect of the present invention, there is provided a gas discharge member of the following embodiment.

[0011] The first embodiment relates to a gas discharge member which is a gas permeable sheet and has holes in the periphery of the sheet.

[0012] In the second embodiment, in the first embodiment, the peripheral portion may be a region corresponding to a length from an end of the sheet to 2 / 5 of the total length of the sheet.

[0013] In a third embodiment, in the first or second embodiment, the width of the peripheral portion may be 2 mm or more from the edge of the sheet.

[0014] In a fourth embodiment, in the third embodiment, the width of the peripheral portion may be 15 mm or less from the edge of the sheet.

[0015] A fifth embodiment is any one of the first to fourth embodiments, wherein the sheet is rectangular, and the holes may be located in the horizontal regions at both ends of the periphery or in the vertical regions at both ends.

[0016] A sixth embodiment is any one of the first to fifth embodiments, wherein the sheet is rectangular, and the holes may be located in both horizontal regions at both ends of the periphery and in both vertical regions at both ends.

[0017] The seventh embodiment is similar to the sixth embodiment, in which the holes may be located in two or more of the horizontal regions at both ends and in two or more of the vertical regions at both ends.

[0018] An eighth embodiment is the seventh embodiment, wherein the holes have a circular or elliptical cross section.

[0019] In the ninth embodiment, in the eighth embodiment, the diameter of the hole may be 10 μm to 500 μm.

[0020] The tenth embodiment is any one of the first to sixth embodiments, in which the hole is rectangular, and one or more of the holes may be located in each of the horizontal regions at both ends, and one or more of the holes may be located in each of the vertical regions at both ends.

[0021] The eleventh embodiment is any one of the first to tenth embodiments, wherein the holes may penetrate the gas exhaust member in a thickness direction of the gas exhaust member.

[0022] The twelfth embodiment is any one of the first to eleventh embodiments, wherein a total area of ​​the holes with respect to a total area of ​​the gas exhaust member may be 5% to 50%.

[0023] The thirteenth embodiment is any one of the first to twelfth embodiments, wherein the gas discharge member has a gas permeability of 40 to 150 barrer at 60°C.

[0024] The fourteenth embodiment is any one of the first to thirteenth embodiments, wherein the gas exhaust member has a moisture permeation amount of 10 mg to 100 mg at 25° C. and 50% RH for 10 years.

[0025] A fifteenth embodiment is any one of the first to fourteenth embodiments, wherein the gas permeable sheet may contain a fluorine-based resin.

[0026] The sixteenth embodiment is any one of the first to fifteenth embodiments, wherein the gas discharge member has a thickness of 50 to 500 μm.

[0027] In order to solve the above problems, according to one aspect of the present invention, there is provided a secondary battery of the following embodiment.

[0028] The seventeenth embodiment relates to a secondary battery including an electrode assembly and a case for housing the electrode assembly therein, the case including an inner resin layer including a gas barrier layer and a sealant resin, an opening penetrating the case in a thickness direction formed in a part of the case, and a gas exhaust member according to any one of the first to sixteenth embodiments bonded to the inside of the opening so as to cover the entire opening, a hole provided in the gas exhaust member is located in a portion overlapping with the inner resin layer of the case, and the sealant resin of the inner resin layer is drawn into the hole provided in the gas exhaust member.

[0029] The 18th embodiment is the 17th embodiment, wherein the case may include a laminate sheet in which an outer resin layer, a gas barrier layer consisting of a metal layer, and an inner resin layer containing a sealant resin are laminated on the gas barrier layer in that order.

[0030] A 19th embodiment is the 17th or 18th embodiment, in which the gas exhaust member is made of a gas permeable sheet containing a fluorine-based resin, and the glass transition temperature of the fluorine-based resin may be higher than the glass transition temperature of the sealant resin.

[0031] A twentieth embodiment is any one of the seventeenth to eighteenth embodiments, wherein the sealant resin may include polypropylene, polyethylene, polyvinyl difluoride (PVDF), or two or more thereof. Effect of the Invention

[0032] A gas discharge member according to an embodiment of the present invention is a gas permeable sheet having holes in its periphery.

[0033] The gas exhaust member, which is configured so that the holes provided in the periphery are located in the area where the gas exhaust member overlaps with the inner resin layer of the battery case, improves the adhesion to the case because the sealant resin contained in the inner resin layer of the case flows and is drawn into the holes when the gas exhaust member is thermally bonded to the case. This improves the efficiency with which gas generated inside the battery cell is discharged through the gas exhaust member, and reduces the phenomenon of moisture penetrating into the battery cell.

[0034] When gas generated inside the battery cell is smoothly discharged through the gas-permeable gas exhaust member and the phenomenon of moisture penetration into the inside of the battery cell is reduced, venting does not occur and the cell can continue to operate smoothly.

[0035] The effects of the present invention are not limited to the effects described above, and effects not mentioned will be clearly understood by a person having ordinary skill in the art to which the present invention pertains from this specification and the accompanying drawings.

[0036] The following drawings attached to this specification illustrate preferred embodiments of the present invention and, together with the detailed description of the invention, serve to further understand the technical ideas of the present invention. Therefore, the present invention should not be interpreted as being limited only to the matters described in the drawings. [Brief description of the drawings]

[0037] [Figure 1] FIG. 2 is a perspective view showing a gas discharge member according to an embodiment of the present invention. [Diagram 2] FIG. 11 is a perspective view showing a gas discharge member according to another embodiment of the present invention. [Diagram 3] FIG. 11 is a perspective view showing a gas discharge member according to still another embodiment of the present invention. [Figure 4] FIG. 2 is a cross-sectional view taken along the AA' axis in FIG. [Diagram 5] 1 is a top view of a secondary battery according to an embodiment of the present invention; [Figure 6] 6 is a cross-sectional view taken along the BB' axis in FIG. 5. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0038] Hereinafter, a preferred embodiment of the present invention will be described in detail with reference to the attached drawings. Prior to this, the terms and words used in the present specification and claims are not to be construed as being limited to their ordinary and dictionary meanings, but are to be construed as having meanings and concepts according to the technical ideas of the present invention, in accordance with the principle that the inventors themselves can appropriately define the concepts of terms in order to best describe the invention.

[0039] Therefore, it should be understood that the configurations shown in the embodiments described in this specification are merely the most preferred embodiments of the present invention and do not represent the entire technical idea of ​​the present invention, and therefore there may be various equivalents and modifications that can be substituted therefor at the time of this application.

[0040] In order to clearly describe the present invention, parts that are not relevant to the description will be omitted, and the same reference numerals will be used to refer to the same or similar components throughout the specification.

[0041] In addition, the size and thickness of each component shown in the drawings are arbitrarily shown for convenience of explanation, and the present invention is not necessarily limited to those shown. In the drawings, the thicknesses of some layers and regions are exaggerated in order to clearly show them. In the drawings, the thicknesses of some layers and regions are exaggerated in order to clearly show them.

[0042] Furthermore, throughout the specification, when a part is said to "include" or "comprise" a certain element, this means that it may further include or comprise other elements, rather than excluding other elements, unless specifically stated to the contrary.

[0043] In addition, throughout the specification, the term "on a plane" means the part being viewed from above, and the term "on a cross section" means the part being viewed from the side along a vertical cross section.

[0044] The gas discharge member according to one aspect of the present invention includes a hole.

[0045] More specifically, the gas discharge member according to one aspect of the present invention is a gas permeable sheet having holes in the periphery of the sheet.

[0046] In this specification, the term "gas-permeable sheet" refers to a member that has a shape with a small thickness relative to its area, such as a commonly used film or sheet, and whose material itself has the property of allowing gas to pass therethrough.

[0047] As described above, if the gas discharge member is not firmly attached to the battery case, the gas discharge ability decreases and moisture from outside the battery cell penetrates into the battery cell, so it is necessary to improve the adhesive strength of the gas discharge member to the battery case. In particular, fluororesins, which are representative of materials for gas discharge members, are excellent in gas permeability (gas discharge performance) and are useful for preventing the penetration of moisture from the outside, but they do not have a strong adhesive strength to the battery case.

[0048] In this way, the present inventors provide a gas discharge member that can improve the adhesive strength to the battery case.

[0049] FIG. 1 is a perspective view showing a gas discharge member according to an embodiment of the present invention.

[0050] 1, a hole 100 is formed in the gas discharge member 1. When the gas discharge member 1 and the battery case are thermally bonded, the sealant resin contained in the inner resin layer of the case flows into the hole 100 and is partially drawn into the hole, thereby improving the bonding strength between the gas discharge member 1 and the case.

[0051] 1, the gas discharge member 1 is a sheet-like member having gas permeability. The shape of the gas discharge member 1 can be rectangular as shown in the figure, but can be modified in various ways as necessary, such as circular or elliptical.

[0052] The holes 100 are provided in the peripheral portion 1b of the gas discharge member 1. The "peripheral portion" of the sheet means the portion that overlaps with the inner resin layer of the case when the gas discharge member 1 is heat-bonded to the inside of the opening of the battery case so as to cover the entire opening of the battery case. In other words, the holes 100 are not positioned so as to overlap with the opening of the case, but are positioned in the "peripheral portion" of the gas discharge member 1, which is the portion that overlaps with the inner resin layer of the case. Conversely, the central portion 1a of the gas discharge member 1 is defined as the portion that overlaps with the opening of the case, excluding the "peripheral portion".

[0053] The peripheral portion 1b may be a region corresponding to a length from an end of the sheet constituting the gas discharge member 1 to 2 / 5 of the total length of the sheet.

[0054] 1, when the sheet constituting the gas discharge member 1 is rectangular, the peripheral portion 1b may be a region 0.4Y corresponding to a length from the end of the sheet to 2 / 5 of the total horizontal length Y and a region 0.4W corresponding to a length from the end of the sheet to 2 / 5 of the total vertical length W. When the hole 100 is formed in such a portion, the gas discharge member 1 can be easily positioned so that the hole 100 does not overlap with the opening of the case but overlaps with the inner resin layer of the case. When the gas discharge member 1 is not rectangular, for example, when it is circular, the peripheral portion 1b may be a region corresponding to a length from the end of the sheet constituting the gas discharge member 1 to 2 / 5 of the sheet diameter.

[0055] For the sake of adhesion stability of the gas discharge member 1 to the battery case, the width of the peripheral portion, for example, 0.4Y and 0.4W in Fig. 1, is preferably 2 mm or more from the edge of the sheet. More specifically, the widths of the peripheral portions, 0.4Y and 0.4W, may be 2 to 15 mm from the edge of the sheet.

[0056] The gas discharge member 1 may have holes 100 formed at both ends. That is, when the sheet constituting the gas discharge member 1 is rectangular, the holes 100 may be located in the horizontal regions at both ends of the peripheral portion (see FIG. 2) or in the vertical regions at both ends. When the holes 100 are formed in this manner, the gas discharge member 1 can be easily attached to the battery case, and gas inside the battery can be easily discharged to the outside. More specifically, as shown in FIG. 1, when the sheet constituting the gas discharge member 1 is rectangular, the holes 100 may be located in both the horizontal regions at both ends of the peripheral portion 1b and the vertical regions at both ends.

[0057] In this specification, the term "hole" refers to a space that is dug in the thickness direction (e.g., 1 / 4 or more of the thickness) to achieve the object of the present invention, whether or not it penetrates the gas exhaust member 1 along the thickness direction. The shape of the hole 100 may have a cross section such as a circle, an ellipse, a triangle, a wave shape, a rectangle, etc., and the shape is not limited, but may have a circle or an ellipse cross section in consideration of process efficiency, etc.

[0058] 1, when the sheet constituting the gas discharge member 1 is rectangular, the holes 100 may be located at two or more in each of the horizontal regions at both ends and at two or more in each of the vertical regions at both ends, in which case the cross section of the holes 100 may be circular or elliptical, and the diameter of the holes 100 may be, but is not limited to, 10 μm to 500 μm. When the diameter of the holes 100 satisfies the above range, the adhesive properties between the gas discharge member 1 and the battery case can be more easily improved.

[0059] Furthermore, as shown in FIG. 3, when the sheet constituting the gas exhaust member 1 is rectangular and the hole 100 is rectangular, one or more holes can be located in each of the horizontal regions at both ends, and one or more holes can be located in each of the vertical regions at both ends, but this is not limited to this.

[0060] The holes 100 may be formed by, for example, a physical or chemical method. For example, the holes 100 may be formed in the gas discharge member 1 using a drill or a laser. Alternatively, the holes 100 may be formed in the gas discharge member 1 by wet etching or pattern printing of a fluorine-based resin.

[0061] In one embodiment of the present invention, the total area of ​​the holes 100 may be 5% to 50% of the total area of ​​the gas exhaust member 1. When the total area of ​​the holes 100 satisfies the above range, the adhesive properties between the gas exhaust member 1 and the case can be more easily improved.

[0062] In one embodiment of the present invention, the sheet constituting the gas exhaust member 1 may contain a fluororesin. The fluororesin may contain repeating units derived from tetrafluoroethylene, vinyl fluoride, vinylidene fluoride, or two or more monomers thereof. In particular, when the fluororesin contains repeating units derived from tetrafluoroethylene, it can be more appropriately used as a material for the gas exhaust member 1.

[0063] In one embodiment of the present invention, the gas permeability of the gas discharge member 1 may be 40 to 150 barrer at 60°C. For example, the permeability to carbon dioxide may satisfy the above-mentioned range. In addition, the gas permeability of the gas discharge member 1 having a thickness of 200 μm may satisfy the above-mentioned range at 60°C. When the gas permeability of the gas discharge member 1 satisfies the above-mentioned range, the gas generated inside the battery can be more effectively discharged. In this specification, the gas permeability may be measured according to ASTM F2476-20.

[0064] In one embodiment of the present invention, the moisture permeation amount of the gas exhausting member 1 may be 10 mg to 100 mg over 10 years at 25° C. and 50% RH. When the moisture permeation amount of the gas exhausting member 1 satisfies the above range, the permeation of moisture entering through the gas exhausting member 1 can be more effectively prevented. The moisture permeation amount of the gas exhausting member 1 may be measured using the ASTM F1249 method. In this case, the measurement may be performed using equipment officially certified by MCOON.

[0065] In one embodiment of the present invention, the gas exhaust member 1 may have a thickness of 50 to 500 μm. When the thickness of the gas exhaust member 1 is within the above range, gas is easily exhausted to the outside and thermal adhesion to the battery case is facilitated.

[0066] FIG. 4 is a cross-sectional view taken along the AA' axis of FIG.

[0067] 4, the holes 100 may be formed penetrating the gas exhaust member 1 in the thickness direction of the gas exhaust member 1. When the holes 100 are formed penetrating the gas exhaust member 1 in the thickness direction of the gas exhaust member 1, the adhesive properties between the gas exhaust member 1 and the battery case can be further improved.

[0068] FIG. 5 is a top view of a secondary battery according to one embodiment of the present invention.

[0069] Referring to FIG. 5, a secondary battery 10 according to an embodiment of the present invention includes an electrode assembly 20 and a case 30 that houses the electrode assembly 20 therein.

[0070] The secondary battery 10 may include an electrode lead 40 and a lead film 50 connected to the electrode assembly 20 .

[0071] The electrode assembly 20 includes a positive electrode plate, a negative electrode plate, and a separator. The electrode assembly 20 includes a positive electrode plate and a negative electrode plate stacked in order with a separator sandwiched therebetween.

[0072] The positive electrode plate may include a positive electrode current collector made of a metal thin plate having excellent conductivity, for example, aluminum (Al) foil, and a positive electrode active material layer coated on at least one surface of the positive electrode current collector. The positive electrode plate may also include a positive electrode tab made of a metal material such as aluminum (Al) at one end. The positive electrode tab may protrude from one end of the positive electrode plate. The positive electrode tab may be welded to one end of the positive electrode plate or attached using a conductive adhesive.

[0073] The negative electrode plate may include a negative electrode current collector made of a conductive metal sheet such as copper (Cu) foil, and a negative electrode active material layer coated on at least one surface of the negative electrode current collector. The negative electrode plate may also include a negative electrode tab made of a metal material such as nickel (Ni) at one end. The negative electrode tab may protrude from one end of the negative electrode plate. The negative electrode tab may be welded to one end of the negative electrode plate or attached using a conductive adhesive.

[0074] The separator is located between the positive electrode plate and the negative electrode plate, and electrically insulates the positive electrode plate and the negative electrode plate. The separator may be a porous membrane that allows lithium ions to pass between the positive electrode plate and the negative electrode plate. The separator may include a porous membrane using, for example, polyethylene (PE), polypropylene (PP), or a composite film thereof.

[0075] An inorganic coating layer may be provided on the surface of the separator. The inorganic coating layer may have a structure in which inorganic particles are bound to each other by a binder to form an interstitial volume between the particles.

[0076] The electrode assembly 20 may be a jelly roll type (wound type) electrode assembly having a structure in which long sheet-like positive and negative electrodes are wound with a separator interposed therebetween, a stack type (lamination type) electrode assembly in which a plurality of positive and negative electrodes cut into units of a predetermined size are sequentially stacked with a separator interposed therebetween, a stack / folded type electrode assembly having a structure in which a bi-cell or a full cell in which positive and negative electrodes of a predetermined unit are stacked with a separator interposed therebetween is wound up, etc.

[0077] The case 30 includes a housing portion 31 for housing the electrode assembly therein, and a sealing portion 32 for forming a structure for sealing the outer periphery. The sealing portion 32 may be sealed by thermal bonding using heat, a laser, or the like.

[0078] The case 30 includes a gas barrier layer and an inner resin layer containing a sealant resin.

[0079] More specifically, the gas barrier layer may be a metal layer. The case 30 may be a laminate sheet including a resin layer and a metal layer. More specifically, the case 30 is made of a laminate sheet and may include an outer resin layer forming the outermost layer, a barrier metal layer that prevents penetration of substances, and an inner resin layer for sealing.

[0080] The outer resin layer may include a polyester-based film using poly(ethylene terephthalate) (PET), polybutylene terephthalate, polyethylene naphthalate, polybutylene naphthalate, copolymer polyester, polycarbonate, nylon, or the like, and may be configured as a single layer or multiple layers.

[0081] The barrier metal layer may include aluminum, copper, and the like.

[0082] The inner resin layer is a layer containing or consisting of a sealant resin, and may be configured as a single layer or multiple layers.

[0083] The sealant resin may include polypropylene (PP), acid modified polypropylene (PPa), random polypropylene, ethylene propylene copolymer, or two or more thereof. The ethylene propylene copolymer may include, but is not limited to, ethylene propylene rubber, ethylene-propylene block copolymer, etc.

[0084] The case 30 may be in the form of a pouch.

[0085] The pouch-shaped case 30 may include an upper pouch and a lower pouch. When the case 30 includes an upper pouch and a lower pouch, the upper pouch and the lower pouch are arranged so that the sealant resins face each other, and then the facing sealant resins are fused to each other by heat and pressure, thereby sealing the battery.

[0086] The sealing portion 32 may be fused by heat or ultrasonic waves, but is not particularly limited as long as the sealing portion 32 can be fused.

[0087] In some embodiments, the sealing portion 32 may seal four or three sides of the edge of the case 30. In a structure in which three sides are sealed, after the upper and lower pouches are formed into one pouch sheet, the interface between the upper and lower pouches is folded so that the storage portions 31 formed in the upper and lower pouches overlap, and the remaining three edges excluding the folded portion are sealed.

[0088] The electrode lead 40 is electrically connected to an electrode tab (not shown) included in the electrode assembly 20, and may protrude outward from the case 30 through the sealing portion 32. In addition, the lead film 50 may be located in a portion corresponding to the sealing portion 32 on at least one of the upper and lower portions of the electrode lead 40. As a result, the lead film 50 can prevent a short circuit from occurring in the electrode lead 40 during fusion, and can improve the sealing property between the sealing portion 32 and the electrode lead 40.

[0089] 5, an opening 60 is formed in a part of the case 30. The opening 60 penetrates the case 30 in the thickness direction. A gas discharge member 1 according to an embodiment of the present invention is bonded to the inside of the opening 60.

[0090] Since the gas discharge member 1 is positioned inside the opening 60, the gas generated inside the battery passes through the gas discharge member 1 and is discharged to the outside of the battery via the opening 60.

[0091] The opening 60 may be formed in at least one of the upper and lower parts of the case 30. That is, only one opening 60 may be formed, or a plurality of openings 60 may be formed.

[0092] 5, an opening 60 may be formed in a portion of the case 30 excluding the sealing portion 32. The opening 60 may be formed by a conventional method such as punching.

[0093] After forming the case 30, and before inserting the electrode assembly 20, the opening 60 may be formed in the case 30. After forming the opening 60, the gas exhaust member 1 according to an embodiment of the present invention may be attached to the inside of the opening 60, thereby manufacturing the secondary battery 10 including the gas exhaust member 1. The gas exhaust member 1 is bonded to cover the entire opening 60.

[0094] The gas exhaust member 1 can be attached by heat fusion to the inside of the opening 60. For example, the gas exhaust member 1 can be attached to the inside of the opening 60 by using a press or the like.

[0095] During this process, a portion of the case 30 that overlaps with the gas exhaust member 1 around the opening 60 may be inserted into a hole in the gas exhaust member 1. For example, the sealant resin of the inner resin layer that overlaps with the gas exhaust member 1 around the opening 60 may flow and be drawn into the hole in the gas exhaust member 1. This can improve the adhesive properties between the gas exhaust member 1 and the case 30.

[0096] In one embodiment of the present invention, the gas exhaust member 1 is made of a gas permeable sheet containing a fluororesin, and the glass transition temperature of the fluororesin may be higher than that of the sealant resin constituting the inner resin layer. When the glass transition temperature of the fluororesin is higher than that of the sealant resin, the sealant resin can easily penetrate into the holes 100 formed in the gas exhaust member 1 when the case 30 and the gas exhaust member 1 are heat-sealed.

[0097] In one embodiment of the present invention, the glass transition temperature of the fluororesin may be 30° C. to 170° C. When the glass transition temperature of the fluororesin satisfies the above range, the sealant resin can easily penetrate into the holes 100 formed in the gas exhaust member 1 when the case 30 and the gas exhaust member 1 are heat-sealed.

[0098] In one embodiment of the present invention, the glass transition temperature of the sealant resin may be −150° C. to 0° C. If the glass transition temperature of the sealant resin satisfies the above range, the sealant resin can easily permeate into the holes 100 formed in the gas exhaust member 1 when the case 30 and the gas exhaust member 1 are heat-sealed.

[0099] In one embodiment of the present invention, the sealant resin may include a polyolefin resin, for example, the polyolefin resin may include polypropylene, polyethylene, polyvinyl difluoride (PVDF), or two or more thereof.

[0100] FIG. 6 is a cross-sectional view taken along the BB' axis of FIG.

[0101] 6, the sealant resin 2 is drawn into the hole 100 of the gas discharge member 1. This makes it possible to easily fix the gas discharge member 1 to the inside of the opening 60.

[0102] 6, an opening 60 is formed in a part of the case, penetrating the case in the thickness direction. The size of the gas exhaust member 1 is larger than the size of the opening 60, and therefore covers the entire opening 60. For example, when the gas exhaust member 1 and the opening 60 have a rectangular shape, the horizontal or vertical length of the gas exhaust member 1 may be larger than the horizontal or vertical length of the opening 60. When the gas exhaust member 1 and the opening 60 have a circular shape, the diameter of the gas exhaust member 1 may be larger than the diameter of the opening 60. When the gas exhaust member 1 has a rectangular shape and the opening 60 has a circular shape, the horizontal or vertical length of the gas exhaust member 1 may be larger than the diameter of the opening 60.

[0103] Since the size of the gas exhaust member 1 is larger than the size of the opening 60, a sufficient area can be secured for adhesion between the gas exhaust member 1 and the inner resin layer located in the storage section 31 of the case. The gas exhaust member 1 can be more easily attached to the case.

[0104] 6, the hole 100 of the gas exhaust member 1 is located at a portion where the gas exhaust member 1 overlaps with the inner resin layer located in the storage section 31 of the case. By locating the hole 100 of the gas exhaust member 1 at a portion where the gas exhaust member 1 overlaps with the inner resin layer located in the storage section 31 of the case, a part of the inner resin layer overlapping with the gas exhaust member 1 can be inserted into the hole 100 of the gas exhaust member 1. That is, the sealant resin 2 of the inner resin layer overlapping with the gas exhaust member 1 around the opening 60 flows due to a process such as heating, laser, or ultrasonic wave, and is drawn into the hole of the gas exhaust member 1. This improves the bonding strength between the gas exhaust member 1 and the case, and also improves the durability of the adhesion.

[0105] Improving the adhesive properties between the gas exhaust member 1 and the case reduces the possibility of a gap occurring between the gas exhaust member 1 and the case even after the battery cell has been in operation for a long time. This improves the efficiency with which gas generated inside the battery cell is discharged through the gas exhaust member, thereby reducing the phenomenon of moisture penetrating into the battery cell.

[0106] When gas generated inside the battery cell is smoothly discharged through the gas-permeable gas exhaust member and the phenomenon of moisture penetration into the inside of the battery cell is reduced, venting does not occur and the cell can continue to operate smoothly.

[0107] Although the preferred embodiments of the present invention have been described in detail above, the scope of the present invention is not limited thereto, and various modifications and improvements made by those skilled in the art using the basic concept of the present invention defined in the following claims also fall within the scope of the present invention. [Explanation of symbols]

[0108] 1 Gas exhaust member 1a central part 1b Periphery 2. Sealant resin drawn in 10 Secondary battery 20 Electrode assembly 30 cases 31 Storage area 32 Sealing section 40 Electrode Lead 50 Lead Film 60 Opening 100 holes

Claims

1. A gas discharge member comprising a gas permeable sheet and a hole for drawing a sealant resin in a peripheral portion of the sheet, The gas exhaust member, wherein the hole penetrates the gas exhaust member in a thickness direction of the gas exhaust member.

2. The gas discharge member according to claim 1 , wherein the peripheral portion is a region corresponding to a length from an end of the sheet to ⅔ of the total length of the sheet.

3. The gas discharge member according to claim 1 , wherein the width of the peripheral portion is 2 mm or more from the edge of the sheet.

4. The gas discharge member according to claim 3 , wherein the width of the peripheral portion is 15 mm or less from the edge of the sheet.

5. 2. The gas discharge member according to claim 1, wherein the sheet is rectangular, and the holes are located in the horizontal regions at both ends of the periphery or in the vertical regions at both ends of the periphery.

6. 2. The gas discharge member according to claim 1, wherein the sheet is rectangular, and the holes are located in both horizontal regions at both ends of the periphery and in both vertical regions at both ends.

7. The gas discharge member according to claim 6 , wherein the holes are located in two or more of the horizontal regions at both ends and in two or more of the vertical regions at both ends.

8. The gas discharge member according to claim 7, wherein the holes have a circular or elliptical cross section.

9. The gas discharge member according to claim 8, wherein the hole has a diameter of 10 to 500 μm.

10. The gas discharge member according to claim 6 , wherein the holes are rectangular, and one or more of the holes are located in each of the horizontal regions at both ends, and one or more of the holes are located in each of the vertical regions at both ends.

11. 2. The gas exhaust member according to claim 1, wherein a total area of ​​the holes is 5% to 50% of a total area of ​​the gas exhaust member.

12. 2. The gas exhaust member according to claim 1, wherein the gas exhaust member has a gas permeability of 40 to 150 barrers at 60[deg.] C.

13. 2. The gas exhaust member according to claim 1, wherein the gas exhaust member has a moisture permeation amount of 10 mg to 100 mg at 25[deg.] C. and 50% RH for 10 years.

14. The gas discharge member according to claim 1 , wherein the gas permeable sheet contains a fluorine-based resin.

15. 2. The gas exhaust member according to claim 1, wherein the gas exhaust member has a thickness of 50 to 500 [mu]m.

16. The electrode assembly includes an electrode assembly and a case for accommodating the electrode assembly therein. the case includes a gas barrier layer and an inner resin layer including a sealant resin; An opening is formed in a part of the case so as to penetrate the case in a thickness direction, The gas exhaust member according to claim 1 is attached to an inside of the opening so as to cover the entire opening, the hole provided in the gas exhaust member is located at a portion overlapping with the inner resin layer of the case, A secondary battery, characterized in that a sealant resin of the inner resin layer is drawn into a hole provided in the gas exhaust member.

17. 17. The secondary battery according to claim 16, wherein the case includes a laminate sheet in which an outer resin layer, a gas barrier layer made of a metal layer, and an inner resin layer laminated on the gas barrier layer and containing a sealant resin are sequentially laminated.

18. 17. The secondary battery according to claim 16, wherein the gas discharge member is made of a gas permeable sheet containing a fluorine-based resin, and the glass transition temperature of the fluorine-based resin is higher than the glass transition temperature of the sealant resin.

19. The secondary battery according to claim 16, wherein the sealant resin comprises polypropylene, polyethylene, polyvinyl difluoride (PVDF), or two or more thereof.

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