Pouch-type battery case, pouch-type secondary battery and battery module comprising the same

Abstract

The present invention relates to a pouch-type battery case comprising a cup portion that accommodates an electrode assembly formed by laminating an electrode and a separator, wherein the cup portion comprises an edge portion, the cup portion comprises a refractory layer disposed on the edge portion, and the refractory layer comprises a foaming agent comprising one or more selected from the group consisting of hydrated alkali metal silicate and hydrated alkaline earth metal silicate.

Description

Technology Field

[0001] The present invention relates to a pouch-type battery case and a pouch-type secondary battery. Background Technology

[0003] Secondary batteries are used not only in small products such as digital cameras, P-DVDs, MP3 players, mobile phones, PDAs, portable game devices, power tools, and E-bikes, but also in large products requiring high output such as electric vehicles and hybrid vehicles, as well as in power storage devices that store surplus power or new and renewable energy and backup power storage devices.

[0004] Secondary batteries are classified into pouch type and can type depending on the material of the case housing the electrode assembly. The pouch type houses the electrode assembly in a pouch made of a flexible polymer material. The can type, on the other hand, houses the electrode assembly in a case made of materials such as metal or plastic.

[0005] A pouch-type battery case is manufactured by performing press processing on a flexible pouch film laminate to form a cup portion. Then, once the cup portion is formed, an electrode assembly is housed in the receiving space of the cup portion and a sealing portion is sealed to manufacture a secondary battery.

[0006] Among these press processes, drawing forming is performed by inserting a pouch film into a press machine and applying pressure to the pouch film laminate with a punch to stretch the pouch film laminate. The pouch film laminate is generally formed of multiple layers in which a polymer film, such as polyethylene terephthalate, is laminated on one side of a metal gas barrier layer, and a sealant layer is laminated on the other side.

[0007] Meanwhile, as the scope of application for secondary batteries expands, demands for their safety are increasing. During the charging and discharging process, the temperature of the electrodes in secondary batteries can rise rapidly, posing a risk of causing fire or explosion. For example, if thermal runaway occurs in a secondary battery equipped in an electric vehicle, thermal propagation can spread to adjacent batteries, modules, and packs. This can lead to large fires or successive explosions that affect surrounding equipment, potentially resulting in casualties and property damage.

[0008] In particular, thermal runaway, such as ignition or explosion, can occur in secondary batteries due to internal factors such as electrolyte leakage, excessive gas generation, or internal short circuits during the charging and discharging process, or due to external impact.

[0009] Meanwhile, as described above, the pouch-type battery case is manufactured by drawing the pouch film laminate, but during the process of applying pressure to the pouch film laminate with a punch to stretch it, bending areas inevitably occur that reduce the durability of the pouch film laminate, and in these areas, thermal runaway and thermal transfer are further exacerbated, and there is a problem of inferior high-temperature safety.

[0010] Therefore, there is a need for a pouch film case that prevents thermal runaway and heat transfer while also providing high-temperature safety. The problem to be solved

[0012] One objective of the present invention is to solve the above-mentioned problems by providing a pouch-type battery case including a cup portion including an edge portion, wherein a refractory layer is disposed on the edge portion to suppress gas generation, thermal runaway, and thermal transfer, thereby providing a pouch-type battery case with excellent high-temperature safety, a pouch-type secondary battery including the same, and a battery module.

[0014] However, the problems that the present invention aims to solve are not limited to those mentioned above, and other unmentioned problems will be clearly understood by those skilled in the art from the description below. means of solving the problem

[0016] [1] The present invention provides a pouch-type battery case comprising a cup portion that accommodates an electrode assembly formed by stacking electrodes and a separator, wherein the cup portion comprises an edge portion, the cup portion comprises a refractory layer disposed on the edge portion, and the refractory layer comprises a foaming agent comprising one or more selected from the group consisting of hydrated alkali metal silicate and hydrated alkaline earth metal silicate.

[0017] [2] In the present invention [1], the edge portion may include a plurality of punch edges formed by connecting a plurality of outer walls surrounding the cup portion and a bottom portion, and rounding.

[0018] [3] In the present invention [1] or [2], the edge portion may include a plurality of die edges formed by connecting a plurality of outer walls surrounding the cup portion and a terrace portion, and rounding.

[0019] [4] In at least one of [1] to [3], the present invention may include a plurality of thickness edges formed by connecting a plurality of outer walls surrounding the cup portion and rounding.

[0020] [5] In at least one of [1] to [4], the present invention may include a punch corner formed by connecting two adjacent punch edges.

[0021] [6] In at least one of [1] to [5] above, the refractory layer may include a foaming agent comprising a hydrated alkali metal silicate.

[0022] [7] In at least one of [1] to [6], the present invention may include a foaming agent comprising hydrated sodium silicate.

[0023] [8] In at least one of [1] to [7], the hydrated sodium silicate may be represented by the following chemical formula 1.

[0024] [Chemical Formula 1]

[0025] (Na2O)·x1(SiO2)·n1(H2O)

[0026] In the above chemical formula 1, 2≤x1≤5 and 0.1≤n1≤10.

[0027] [9] In at least one of [1] to [8], the present invention may further include one or more types selected from the group consisting of inorganic fillers and resins.

[0028]

[10] In at least one of [1] to [9], the inorganic filler may comprise one or more selected from the group consisting of titanium dioxide, alumina, kaolin, zirconia, silica, zinc oxide and boehmite.

[0029]

[11] In at least one of [1] to

[10] above, the resin may comprise one or more selected from the group consisting of styrene-butadiene rubber, phenol resin, polyester resin, epoxy resin, polysiloxane resin, polyurethane resin, polyvinyl acetate, carboxymethylcellulose and nitrile rubber.

[0030]

[12] In at least one of [1] to

[11] , the refractory layer may have a thickness of 1 μm or more.

[0031]

[13] In at least one of [1] to

[12] , the refractory layer can expand at a temperature of 130°C or higher.

[0032]

[14] The present invention provides a pouch-type secondary battery comprising at least one of the pouch-type battery cases [1] to

[13] .

[0033]

[15] The present invention provides a battery module comprising the pouch-type secondary battery of

[14] . Effects of the invention

[0035] A pouch-type battery case according to the present invention comprises a cup portion, wherein the cup portion includes an edge portion and is characterized by having a refractory layer disposed on the edge portion. Through the refractory layer, which undergoes rapid expansion due to hydrate decomposition at high temperatures as described above, gas generation, thermal runaway, and thermal transfer are suppressed, thereby providing excellent high-temperature safety. Brief explanation of the drawing

[0037] The drawings attached to this specification illustrate preferred embodiments of the present invention and serve to help to better understand the technical concept of the present invention together with the description of the invention above; therefore, the present invention is not to be interpreted as being limited only to the matters described in such drawings. Meanwhile, the shape, size, scale, or ratio of elements in the drawings included in this specification may be exaggerated to emphasize a clearer explanation. FIG. 1 is an exploded assembly diagram of a pouch-type secondary battery according to one embodiment of the present invention. FIG. 2 is a cross-sectional view of a pouch-type battery case to explain the radius of curvature of the die edge and punch edge formed in the cup portion of the pouch-type battery case according to one embodiment of the present invention. FIG. 3 is a figure illustrating a part of a pouch-type battery case to explain the punch corner formed in the cup portion of a pouch-type battery case according to one embodiment of the present invention, and the respective length and thickness edges of the punch corner. Specific details for implementing the invention

[0038] The present invention will be described more preferably below.

[0039] Terms and words used in this specification and claims should not be interpreted as being limited to their ordinary or dictionary meanings, but should be interpreted in a meaning and concept consistent with the technical spirit of the invention, based on the principle that the inventor can appropriately define the concept of the terms to best describe his invention.

[0040] The terms used in this invention are used merely to describe exemplary embodiments and are not intended to limit the invention. The singular expression includes the plural expression unless the context clearly indicates otherwise.

[0041] In the present invention, terms such as “comprising,” “having,” or “having” are intended to specify the existence of the implemented features, numbers, steps, components, or combinations thereof, and should be understood as not excluding in advance the existence or addition of one or more other features, numbers, steps, components, or combinations thereof.

[0042] In the present invention, the MD direction (Machine Direction) refers to the length direction of the pouch film laminate, and the TD direction (Transverse Direction) refers to the width direction of the pouch film laminate.

[0044] As a result of repeated research to prevent thermal runaway and thermal propagation occurring due to poor high-temperature safety of secondary batteries, the inventors discovered that in a pouch-type battery case including a cup portion, if a refractory layer is placed on the edge portion, which is a curved part formed in the cup portion, gas ejection, thermal runaway, and thermal propagation originating from the edge portion with weak durability can be prevented, thereby enabling excellent high-temperature safety, and thus completed the present invention.

[0046] The present invention will be described in a preferred manner below.

[0048] The pouch-type battery case, pouch-type secondary battery, and battery module according to the present invention include at least one of the configurations disclosed below, and may include any combination of technically feasible configurations among the configurations below.

[0049] Hereinafter, the present invention will be preferably described with reference to FIGS. 1 to 3.

[0051] Pouch-type battery case (210)

[0052] FIGS. 1 to 3 are exploded views of a pouch-type secondary battery (200) including a pouch-type battery case (210) according to one embodiment of the present invention, and drawings illustrating a part of the pouch-type battery case (210). Hereinafter, each configuration of the pouch-type battery case (210) of the present invention will be described in more detail with reference to FIGS. 1 to 3.

[0054] The pouch-type case (210) according to the present invention is a pouch-type battery case (210) comprising a cup portion (222, 232, 301) that accommodates an electrode assembly (260) formed by laminating an electrode and a separator, wherein the cup portion includes an edge portion, and the cup portion (222, 232, 301) includes a refractory layer disposed on the edge portion, and the refractory layer includes a foaming agent comprising one or more selected from the group consisting of hydrated alkali metal silicate and hydrated alkaline earth metal silicate.

[0056] Although pouch-type battery cases are manufactured through drawing molding, during the process of applying pressure to the pouch film laminate with a punch to stretch it, curved areas, or edges, that inevitably occur, which reduce the durability of the pouch film laminate.

[0057] Since durability is reduced at these edge portions due to elongation, if the battery is exposed to high temperatures or if the temperature rises rapidly during charging and discharging, ignition gases may be ejected from the edge portions, causing thermal runaway and heat propagation to occur or accelerate, resulting in a decline in high-temperature safety.

[0058] Accordingly, the present invention aims to improve high-temperature safety by introducing a refractory layer to the edge portion with weak durability to suppress the possibility of gas ejection and reduce the possibility of oxygen exposure among combustion elements, while suppressing thermal runaway and heat transfer by utilizing the characteristic of rapid expansion upon exposure to high temperatures, and blocking or delaying the flame to an adjacent cell.

[0060] According to one embodiment of the present invention, the cup portion (222, 232, 301) includes an edge portion. Preferably, the cup portion (222, 232, 301) may include an edge portion formed by rounding at least one of the corners.

[0061] The above cup portion (222, 232, 301) may form a receiving portion (224), which is a receiving space formed in the shape of a pocket on the inside. The receiving portion (224) may accommodate an electrode assembly.

[0062] Further details regarding the above edge portion will be described later.

[0064] According to one embodiment of the present invention, the cup portion (222, 232, 301) includes a refractory layer disposed on the edge portion, and the refractory layer includes a foaming agent comprising one or more selected from the group consisting of hydrated alkali metal silicate and hydrated alkaline earth metal silicate.

[0065] The above refractory layer is placed on the edge portion where durability is inferior. Through the refractory layer, the durability of the edge portion is improved, thereby preventing the possibility of gas ejection and oxygen exposure, which can enhance high-temperature safety. Furthermore, since the refractory layer contains a foaming agent, when the refractory layer is exposed to high temperatures, it can block or delay the spread of flames to adjacent secondary batteries through rapid expansion caused by the evaporation of moisture and the decomposition of hydrates within the refractory layer, thereby suppressing additional ignition and enabling excellent high-temperature safety.

[0066] For example, when a refractory layer is heated above a certain temperature, the foaming agent releases moisture due to the heat. At this time, as the moisture vaporizes due to the heat, it increases internal pressure and causes the refractory layer to expand.

[0067] As described above, when moisture is released as a gas, bubbles are generated within the refractory layer. Consequently, foam with a porous structure is formed within the expanded refractory layer, enabling the refractory layer to function as a type of thermal insulator with excellent fire resistance and heat resistance. Furthermore, the refractory layer with the foam formed therein can not only prevent the transfer of heat or fire by increasing the distance between secondary batteries, but also delay the temperature rise resulting from the increased distance between secondary batteries.

[0068] Therefore, the refractory layer can prevent and / or delay thermal runaway and heat transfer occurring at the edge portions with inferior durability, thereby enabling excellent high-temperature safety. Furthermore, unlike structures in which a refractory pad capable of acting as an insulator is placed between batteries, the present invention places the refractory layer only on the edge portions with inferior durability; thus, it does not affect the overall thickness change of the battery, thereby enabling excellent energy density, and provides an excellent temperature delay effect through increased physical distance compared to insulators that do not perform an expansion function.

[0070] The present invention will be described in more detail below.

[0072] (1) Cup section (222, 232, 301)

[0073] Referring to FIGS. 2 and FIGS. 3, the cup portion (301) will be described in detail.

[0075] According to one embodiment of the present invention, the cup portion (301) includes an edge portion. Preferably, the cup portion (301) includes an edge portion formed by rounding at least one of the corners.

[0076] The above corner may refer to a line segment formed where the outer wall (250) of the cup portion meets the outer wall (250), may refer to a line segment formed where the outer wall (250) of the cup portion meets the terrace portion (240), and may refer to a line segment formed where the outer wall (250) of the cup portion meets the bottom portion.

[0078] According to one embodiment of the present invention, the edge portion may include a plurality of punch edges (401) formed by connecting a plurality of outer walls (250) surrounding the cup portion (301) and a bottom portion, and being rounded.

[0079] If the punch edge (401) is not rounded, the punch edge (401) becomes sharp, so when forming the pouch film laminate, stress is concentrated on the punch edge (401) of the cup portion (301), causing a problem where cracks easily occur. To solve the above problem, as shown in FIG. 3, the punch edge (401) can be formed by rounding within a specific radius of curvature. The punch edge (401) formed by rounding within a specific radius of curvature can disperse the stress concentrated thereon to some extent.

[0080] Therefore, when the above conditions are satisfied, excellent moldability can be achieved, and a refractory layer can be placed on the punch edge (401) which has weak durability, thereby achieving excellent high-temperature safety.

[0081] Here, "rounded" means forming a curved surface to have a curvature, and such a curved surface may have only a constant curvature, but is not limited thereto and may have a non-constant curvature. In this specification, the statement that the punch edge (401), die edge (402), thickness edge (403), punch corner (303), etc. are formed by being rounded with a specific curvature means that it includes not only having only the specific curvature as a whole, but also having the specific curvature in at least a part.

[0083] Referring to FIG. 2, it can be seen that when the cup portion (301) and the storage portion (302) are in the above positions among the pouch-type battery case (210), the radius of curvature (R1) of the punch edge (401) and the radius of curvature (R2) of the die edge (402) are shown.

[0085] According to one embodiment of the present invention, the punch edge (401) may be formed by rounding with a radius of curvature of 5 mm or less, preferably by rounding with a radius of curvature of 4 mm or less, more preferably by rounding with a radius of curvature of 0.01 mm to 4.0 mm, and even more preferably by rounding with a radius of curvature of 0.01 mm to 3.0 mm. Satisfying the above range is desirable in that it can appropriately distribute the stress applied to the punch edge while achieving excellent energy density.

[0087] According to one embodiment of the present invention, the edge portion may include a plurality of die edges (402) formed by rounding, which connect a plurality of outer walls (250) surrounding the cup portion (301) and a terrace portion (240). The terrace portion (240) may be a portion forming the rim of the cup portion (301) and may be a portion formed along the edge of the cup portion (301).

[0088] If the die edge (402) is not rounded, the die edge (402) becomes sharp, so when forming the pouch film laminate, stress is concentrated on the die edge (402) of the cup portion (301), causing a problem where cracks easily occur. To solve the above problem, as shown in FIG. 3, the die edge (402) can be formed by rounding within a specific radius of curvature. The die edge (402) formed by rounding within a specific radius of curvature can disperse the stress concentrated thereon to some extent.

[0089] Therefore, when the above conditions are satisfied, excellent moldability can be achieved, and a refractory layer can be placed on the die edge (402) which has poor durability, thereby achieving excellent high-temperature safety.

[0091] According to one embodiment of the present invention, the die edge (402) may be formed by rounding with a radius of curvature of 5 mm or less, preferably by rounding with a radius of curvature of 4 mm or less, more preferably by rounding with a radius of curvature of 0.01 mm to 4.00 mm, and even more preferably by rounding with a radius of curvature of 0.01 mm to 3.00 mm. Satisfying the above range is desirable in that it can appropriately distribute the stress applied to the die edge while achieving excellent energy density.

[0093] According to one embodiment of the present invention, the edge portion may include a plurality of thickness edges (403) formed by connecting a plurality of outer walls (250) surrounding the cup portion (301) to each other and rounding. When the above conditions are satisfied, excellent moldability can be achieved, and a refractory layer can be placed even on the thickness edges (403) which have low durability, thereby achieving excellent high-temperature safety.

[0094] As shown in FIG. 3, the thickness edge (403) is formed in the thickness direction of the cup portion (301), and at least one of the thickness edges (403) may be formed with a rounded shape. As shown in FIG. 3, this thickness edge (403) may be connected to two adjacent punch edges (301) to form a punch corner (303) to be described later.

[0095] According to one embodiment of the present invention, the thickness edge (403) may have a radius of curvature that is the same as, or different from, the radius of curvature (R1) of at least one of two adjacent punch edges. For example, the thickness edge (403) may be formed by rounding with a radius of curvature of 0.5 mm to 5.0 mm, and preferably, the thickness edge (403) may be formed by rounding with a radius of curvature of 0.5 mm to 4.0 mm. More preferably, the thickness edge (403) may be formed by rounding with a radius of curvature of 0.5 mm to 3.0 mm, and even more preferably, the thickness edge (403) may be formed by rounding with a radius of curvature of 0.5 mm to 2.0 mm. When the above ranges are satisfied, the stress applied to the thickness edge can be appropriately distributed, thereby suppressing whitening and / or cracking.

[0097] According to one embodiment of the present invention, the edge portion may include a punch corner (303) formed by connecting two adjacent punch edges (401), and preferably, the edge portion may include a punch corner (303) formed by connecting two adjacent punch edges (401) and one thickness edge (403).

[0098] Referring to FIG. 3, it can be seen that a punch edge (401), a punch corner (303), and a thickness edge (403) formed in the cup portion (301) of a pouch-type battery case (210) are shown.

[0099] As shown in FIG. 3, the punch corner (303) is a type of vertex formed by the meeting of two or three edges. Specifically, since it is formed by the meeting of two punch edges and one thickness edge, there is a problem in that stress is further concentrated at the punch corner (303) when the pouch film laminate is stretched. To solve the above problem, as shown in FIG. 3, the punch corner (303) can be formed by rounding within a specific radius of curvature. Therefore, the punch corner (303) formed by rounding within a specific radius of curvature can disperse the stress concentrated thereon to some extent.

[0100] For example, the radius of curvature of the punch corner (303) may vary internally. That is, the radius of curvature at the center of the punch corner (303) and the radius of curvature at the periphery of the punch corner (303) may differ from each other. In particular, the radius of curvature at the center of the punch corner (303) may be larger than the radius of curvature at the periphery of the punch corner (303). For example, since the radius of curvature at the periphery of the punch corner (303) is relatively adjacent to two punch edges and one thickness edge, it may be equal to the radius of curvature of at least one of the two punch edges and the thickness edge. On the other hand, since the radius of curvature at the center of the punch corner (303) is relatively spaced from two punch edges and one thickness edge, it may be larger than the radius of curvature of at least one of the punch edges and the thickness edge. That is, the radius of curvature of the punch corner (303) may be greater than the radius of curvature of at least one of the punch edge (401) and the thickness edge (403).

[0101] Accordingly, the radius of curvature of the punch corner (303) can increase from the periphery of the punch corner (303) toward the center of the punch corner (303). And as described above, since the radius of curvature of the punch corner (303) is not constant and can change internally, the center of the punch corner (303) may have an aspherical shape rather than a perfect sphere.

[0102] Additionally, the punch corner (303) may need to clearly define not only the radius of curvature but also the range formed in the cup portion (301). If the range of the punch corner (303) formed in the cup portion (301) is excessively narrow, the elongation of the pouch film laminate is still excessive, and there is a problem of whitening or cracking occurring. On the other hand, if the range of the punch corner (303) formed in the cup portion (301) is excessively wide, the space between the outer wall of the cup portion (301) and the electrode assembly is reduced, so the energy density relative to the volume of the secondary battery may increase.

[0103] According to one embodiment of the present invention, as shown in FIG. 3, the punch corner (303) may be formed within 2 mm to 5.0 mm in the thickness direction (R3) of the cup portion (301) from the punch edge (401), within 2 mm to 5.0 mm in the length direction (R4) of the cup portion (301) from the thickness edge (403), and within 2 mm to 5.0 mm in the width direction (R5) of the cup portion (301) from the thickness edge (403). The range in which the punch corner (303) is formed may become wider as the depth of the cup portion (301) increases. By forming the punch corner (303) of the cup portion (301) as described above, the stress concentrated more on the punch corner (303) can be dispersed, thereby preventing problems such as whitening and cracking.

[0105] According to one embodiment of the present invention, the cup portion (301) may include a refractory layer disposed on the punch corner (303). When the above conditions are satisfied, the refractory layer is disposed on the corner portion with inferior durability to prevent gas discharge and oxygen contact, and excellent high-temperature safety can be achieved.

[0107] (2) Refractory layer

[0108] The refractory layer is described below.

[0110] According to one embodiment of the present invention, the cup portion comprises a refractory layer disposed on the edge portion, and the refractory layer may comprise a foaming agent comprising one or more selected from the group consisting of hydrated alkali metal silicates and hydrated alkaline earth metal silicates. For example, it may comprise a foaming agent comprising one or more selected from the group consisting of hydrated lithium silicate, hydrated sodium silicate, hydrated potassium silicate, and hydrated magnesium silicate. When the above conditions are satisfied, excellent high-temperature safety can be achieved by appropriately blocking the possibility of gas ejection and oxygen contact, while also appropriately forming a type of porous foam structure that expands due to heat, thereby preventing and / or delaying thermal runaway and heat transfer.

[0111] Preferably, the refractory layer may include a foaming agent comprising a hydrated alkali metal silicate, and more preferably, the refractory layer may include a foaming agent comprising a hydrated sodium silicate. When the above conditions are satisfied, the possibility of gas ejection and oxygen contact can be appropriately blocked, and a foam of a porous structure formed by expansion due to heat can be appropriately formed, thereby preventing and / or delaying thermal runaway and heat transfer, and thus achieving excellent high-temperature safety.

[0113] According to one embodiment of the present invention, the hydrated sodium silicate may be represented by the following chemical formula 1.

[0114] [Chemical Formula 1]

[0115] (Na2O)·x1(SiO2)·n1(H2O)

[0116] In the above chemical formula 1,

[0117] The above x1 is the molar ratio of SiO2 to 1 mole of Na2O, and 2≤x1≤5.

[0118] The above n1 is the molar ratio of H2O to 1 mole of Na2O, and may be 0.1≤n1≤10.

[0120] According to one embodiment of the present invention, the foaming agent may be included in an amount of 20 parts by weight or more per 100 parts by weight of the refractory layer, and preferably in an amount of 20 to 90 parts by weight per 100 parts by weight of the refractory layer. This may be desirable in that it has an excellent volume expansion rate, thereby increasing thermal insulation and improving durability.

[0122] According to one embodiment of the present invention, the foaming agent may further include additives to improve volume expansion rate and thermal insulation, and may further include, for example, one or more selected from vermiculite and perlite.

[0124] According to one embodiment of the present invention, the refractory layer may further include one or more materials selected from the group consisting of inorganic fillers and resins. When the above conditions are satisfied, thermal insulation and durability can be improved.

[0126] According to one embodiment of the present invention, the inorganic filler may include one or more selected from the group consisting of titanium dioxide, alumina, kaolin, zirconia, silica, zinc oxide, and boehmite. When the above conditions are satisfied, high-temperature safety can be improved by enhancing thermal insulation and durability.

[0128] According to one embodiment of the present invention, the inorganic filler may be included in an amount of 50 parts by weight or less per 100 parts by weight of the refractory layer. This may be desirable in terms of improving fire resistance and durability.

[0130] According to one embodiment of the present invention, the resin is intended to improve adhesion and flexibility and may include one or more selected from the group consisting of styrene-butadiene rubber, phenol resin, polyester resin, epoxy resin, polysiloxane resin, polyurethane resin, polyvinyl acetate, carboxymethylcellulose, and nitrile rubber. By including such a resin in the refractory layer, the flexibility of the refractory layer can be improved and the adhesion to organic materials can be improved. Preferably, the organic binder may be one or more selected from the group consisting of styrene-butadiene rubber, epoxy resin, and polyurethane resin.

[0132] According to one embodiment of the present invention, the resin may be included in an amount of 50 parts by weight or less per 100 parts by weight of the refractory layer. Satisfying the above range may be desirable in terms of improving fire resistance, flexibility, adhesion, and durability.

[0134] According to one embodiment of the present invention, the refractory layer may have a thickness of 1 μm or more, preferably 1 μm to 5000 μm, more preferably 10 μm to 3000 μm, and even more preferably 100 μm to 1000 μm. Satisfying the above range may be desirable in that it can easily prevent thermal runaway and thermal transfer, while also preventing the detachment of the refractory layer.

[0136] According to one embodiment of the present invention, the refractory layer can expand at a temperature of 130°C or higher, and preferably at a temperature of 130°C to 150°C. For example, the refractory layer can form a foam structure having a porous structure at a temperature of 130°C or higher, and preferably at a temperature of 130°C to 150°C. That is, when the secondary battery operates within a normal temperature range, the refractory layer performs the role of improving heat resistance and preventing gas ejection and contact with oxygen, but when the secondary battery reaches a high temperature due to abnormal operation, it can perform the role of preventing fire and heat transfer.

[0138] According to one embodiment of the present invention, a pouch-type battery case (210) may include a first case (220) and a second case (230) as shown in FIG. 1. The first case (220) includes a receiving portion (224) capable of receiving an electrode assembly (260), and the second case (230) may cover the receiving portion (224) from above so that the electrode assembly (260) does not escape to the outside of the battery case (210). The first case (220) and the second case (230) may be manufactured with one side connected to the other, but are not limited thereto and may be manufactured in various ways, such as being separated from each other and manufactured separately.

[0140] According to one embodiment of the present invention, the pouch-type battery case (210) may include two symmetrical cup portions (222, 232). At this time, after housing an electrode assembly (260) in a receiving portion (224) provided in the cup portion (222) of the first case (220), the first terrace portion (241) formed between the two cup portions (222, 232) may be folded so that the two cup portions (222, 232) face each other. In this case, the cup portion (232) of the second case (230) may receive the electrode assembly (260) from above. Therefore, since the two cup portions (222, 232) receive one electrode assembly (260), an electrode assembly (260) with a thicker thickness than when there is only one cup portion (222) can be received. In addition, since one corner of the pouch-type secondary battery (200) is formed by folding the pouch-type battery case (210), the number of corners to be sealed can be reduced when performing a sealing process later. Accordingly, the processing speed of the pouch-type secondary battery (200) can be improved and the number of sealing processes can be reduced.

[0142] According to one embodiment of the present invention, a pouch-type battery case (210) may be sealed while accommodating an electrode assembly (260) such that a part of the electrode lead (280), which will be described later, i.e., a terminal part, is exposed. Preferably, the electrode lead (280) is connected to the electrode tab (270) of the electrode assembly (260), and an insulating part (290) is formed on a part of the electrode lead (280). Then, the electrode assembly (260) is accommodated in a receiving part (224) provided in the cup part (222) of the first case (220), and the second case (230) can cover the receiving part (224) from above. Subsequently, an electrolyte is injected into the interior of the receiving part (224), and a sealing part formed on the edges of the first case (220) and the second case (230), for example, the second to fourth terrace parts (242, 243, 244), can be sealed.

[0143] The second to fourth terrace sections (242, 243, 244) can perform the function of sealing the receiving section (224). Preferably, the second to fourth terrace sections (242, 243, 244) can seal the receiving section (224) while being formed along the edge of the receiving section (224). The sealing temperature of the second to fourth terrace sections (242, 243, 244) may be 180°C to 250°C, preferably 200°C to 250°C, and more preferably 210°C to 240°C. When the sealing temperature satisfies the above numerical range, the pouch-type battery case (210) can secure sufficient sealing strength by thermal bonding.

[0145] According to one embodiment of the present invention, a pouch-type battery case (210) according to the present invention can be manufactured using a pouch film laminate, and preferably, the pouch-type battery case (210) can be manufactured by drawing molding the pouch film laminate.

[0146] The pouch film laminate will be described in detail below.

[0148] (Pouch film laminate)

[0149] According to one embodiment of the present invention, a pouch film laminate may include a sequentially laminated substrate layer, a gas barrier layer, and a sealant layer.

[0151] 1) Base layer

[0152] The substrate layer is disposed on the outermost layer of the battery case to protect the electrode assembly from external shocks, electrically insulate it, and assist in stretching, and the substrate layer may comprise one or more of polyethylene terephthalate (PET) and nylon.

[0153] According to one embodiment of the present invention, the substrate layer may have a laminated structure of a polyethylene terephthalate (PET) film and a nylon film. In this case, it is preferable that the nylon film is positioned toward the gas barrier layer side, i.e., the inner side, and the polyethylene terephthalate film is positioned toward the surface side of the battery case.

[0154] Polyethylene terephthalate (PET) exhibits excellent durability and electrical insulation properties; therefore, when a PET film is placed on the surface side, it demonstrates superior durability and insulation. However, because PET films have weak adhesion to the aluminum alloy thin film constituting the gas barrier layer and exhibit different elongation behavior, placing the PET film on the gas barrier layer side may result in delamination between the substrate layer and the gas barrier layer during the molding process. Furthermore, uneven elongation of the gas barrier layer can lead to reduced moldability. In contrast, since nylon films exhibit similar elongation behavior to the aluminum alloy thin film constituting the gas barrier layer, placing a nylon film between the polyethylene terephthalate and the gas barrier layer can improve moldability.

[0155] The thickness of the above substrate layer may be 5㎛ to 70㎛, specifically 7㎛ to 65㎛, more specifically 10㎛ to 60㎛. When the above range is satisfied, excellent formability and post-molding rigidity may be exhibited.

[0156] In addition, when the substrate layer is a laminated structure of a polyethylene terephthalate (PET) film and a nylon film, the polyethylene terephthalate film may have a thickness of 5 µm to 30 µm, preferably 7 µm to 30 µm, more preferably 10 µm to 27 µm, and the nylon film may have a thickness of 10 µm to 60 µm, preferably 10 µm to 55 µm, more preferably 12 µm to 50 µm. When the thicknesses of the polyethylene terephthalate film and the nylon film satisfy the above ranges, excellent moldability and rigidity after molding may be exhibited.

[0158] 2) Gas barrier layer

[0159] The gas barrier layer is laminated between the substrate layer and the sealant layer to ensure the mechanical strength of the pouch, block the entry of gases or moisture from the outside of the secondary battery, and prevent electrolyte leakage from the inside of the pouch-type battery case.

[0160] The gas barrier layer may be formed of a metal. For example, the gas barrier layer may be a metal thin film comprising one or more metals selected from the group consisting of aluminum (Al), copper (Cu), stainless steel (SUS), nickel (Ni), titanium (Ti), and Invar, but is not limited thereto.

[0161] According to one embodiment of the present invention, the gas barrier layer may be formed from an aluminum alloy thin film. When a gas barrier layer is formed using an aluminum alloy thin film, it is possible to secure mechanical strength of a predetermined level or higher, while also ensuring light weight, complementarity to electrochemical properties of the electrode assembly and electrolyte, and heat dissipation. The aluminum alloy thin film may contain elements other than aluminum (Al). For example, the aluminum alloy thin film may contain one or more selected from the group consisting of iron (Fe), copper (Cu), chromium (Cr), manganese (Mn), nickel (Ni), magnesium (Mg), silicon (Si), and zinc (Zn).

[0162] In another example, the gas barrier layer may be formed from a stainless steel thin film. Specifically, the gas barrier layer may be manufactured by forming and / or processing a stainless steel thin film. The gas barrier layer formed from stainless steel has relatively low thermal conductivity, making it effective in preventing or delaying heat diffusion to other cells during thermal runaway, and has relatively high toughness, which can suppress the occurrence of cracks in the pouch during use of the pouch-type battery. The stainless steel may include one or more elements other than iron (Fe), selected from the group consisting of copper (Cu), chromium (Cr), manganese (Mn), nickel (Ni), magnesium (Mg), silicon (Si), and zinc (Zn).

[0163] The thickness of the gas barrier layer may be 20㎛ to 200㎛, preferably 30㎛ to 150㎛, more preferably 40㎛ to 150㎛, and even more preferably 40㎛ to 120㎛. Satisfying the above range is desirable in that it can adequately block the entry and exit of gases or moisture, etc., from outside the secondary battery and adequately prevent leakage of electrolyte from inside the pouch-type battery case. In addition, it can improve moldability and gas barrier performance during the molding of the cup portion.

[0165] 3) Sealant layer

[0166] The sealant layer is intended to completely seal the interior of a pouch-type battery case by mutually thermally bonding at the sealing portion when the pouch-type battery case, which accommodates an electrode assembly on the inside, is sealed. To this end, the sealant layer may be formed from a material having excellent thermal bonding strength.

[0167] The sealant layer can be formed from a material having insulating, corrosion-resistant, and sealing properties. Preferably, since the sealant layer comes into direct contact with the electrode assembly and / or electrolyte inside the pouch-type battery case, it can be formed from a material having insulating and corrosion-resistant properties. Additionally, since the sealant layer must completely seal the inside of the pouch-type battery case to block material transfer between the inside and outside, it can be formed from a material having high sealing properties (e.g., excellent thermal sealing strength). To ensure these insulating, corrosion-resistant, and sealing properties, the sealant layer can be formed from a polymer material.

[0168] The sealant layer (30) may be composed of one or more materials selected from the group consisting of polyethylene, polypropylene, polycarbonate, polyethylene terephthalate, polyvinyl chloride, acrylic polymer, polyacrylonitrile, polyimide, polyamide, cellulose, aramid, nylon, polyester, polyparaphenylenebenzobisoxazole, polyarylate, Teflon, and glass fiber, and preferably may be composed of a polyolefin resin such as polypropylene (PP) and / or polyethylene (PE). In this case, the polypropylene may be composed of cast polypropylene (CPP), acid modified polypropylene (PPA), polypropylene-ethylene copolymer and / or polypropylene-butylene-ethylene terpolymer.

[0169] The thickness of the sealant layer may be 10㎛ to 200㎛, preferably 30㎛ to 180㎛, and more preferably 50㎛ to 150㎛. When the thickness of the sealant layer satisfies the above range, it has the effect of ensuring the sealing strength of the sealing portion while also ensuring the moldability of the pouch film laminate.

[0171] According to one embodiment of the present invention, the sealant layer may have a single-film structure composed of any one material, preferably a single-film structure composed of polypropylene (PP). Alternatively, the sealant layer may have a composite-film structure formed by two or more materials forming separate layers. Preferably, the sealant layer may include a first sealant layer and a second sealant layer. In this case, the first sealant layer may be a layer disposed adjacent to a gas barrier layer, and the second sealant layer may be a layer disposed on the first sealant layer. The first sealant layer and the second sealant layer may each be made of materials with different materials and / or physical properties. An interface may exist between the first sealant layer and the second sealant layer. This means that the first sealant layer and the second sealant layer are different layers and may be formed separately.

[0172] It is particularly preferable that the first sealant layer be made of acid-modified polypropylene (PPa) to ensure long-term adhesion performance between the gas barrier layer and the first sealant layer. Here, the acid-modified polypropylene may be maleic anhydride polypropylene (MAH PP).

[0173] The second sealant layer may be formed from a material having insulating, corrosion-resistant, and sealing properties. Preferably, since the second sealant layer comes into direct contact with the electrode assembly and / or electrolyte inside the receiving space, it may be formed from a material having insulating and corrosion-resistant properties. Additionally, since the second sealant layer must completely seal the inside of the battery case to block material transfer between the inside and outside, it may be formed from a material having high sealing properties. To ensure such insulating, corrosion-resistant, and sealing properties, the second sealant layer may be composed of one or more materials selected from the group consisting of polyethylene, polypropylene, polycarbonate, polyethylene terephthalate, polyvinyl chloride, acrylic polymer, polyacrylonitrile, polyimide, polyamide, cellulose, aramid, nylon, polyester, polyparaphenylenebenzobisoxazole, polyarylate, Teflon, and glass fiber. Preferably, the second sealant layer may be composed of a polyolefin resin such as polypropylene (PP) and / or polyethylene (PE). In this case, the polypropylene may consist of unoriented polypropylene, acid-modified polypropylene, a polypropylene-ethylene copolymer, and / or a polypropylene-butylene-ethylene terpolymer. Here, the acid-modified polypropylene may be maleic anhydride polypropylene (MAH PP). More preferably, the second sealant layer may include unoriented polypropylene (cast polypropylene, CPP) which has heat sealing properties and high tensile strength.

[0175] The pouch film laminate of the present invention described above can be manufactured through a method for manufacturing a pouch film laminate known in the art. For example, the pouch film laminate of the present invention can be manufactured by a method of attaching a substrate layer to the upper surface of a gas barrier layer using an adhesive and forming a sealant layer on the lower surface of the gas barrier layer using co-extrusion or an adhesive layer, or by a method such as dry lamination or sandwich lamination. However, the method for manufacturing the pouch film laminate is not limited thereto.

[0177] According to one embodiment of the present invention, the pouch film laminate may have a thickness of 100 μm to 400 μm, preferably 110 μm to 350 μm, and more preferably 120 μm to 300 μm. When the thickness of the pouch film laminate satisfies the above range, the molding depth can be increased while minimizing the reduction in the battery receiving space and the decrease in sealing durability caused by the increase in the thickness of the pouch laminate.

[0179] According to one embodiment of the present invention, the pouch film laminate may further include an adhesive layer between the gas barrier layer and the substrate layer. For example, the adhesive layer may include a polypropylene-based resin, but is not limited thereto. When the above conditions are satisfied, delamination between the insulating auxiliary layer and the gas barrier layer can be prevented, and excellent moldability can be achieved.

[0181] Pouch-type secondary battery (200)

[0182] Next, a pouch-type secondary battery (200) according to the present invention will be described.

[0183] FIG. 1 is an exploded assembly diagram of a pouch-type secondary battery (200) according to the present invention. As shown in FIG. 1, the pouch-type secondary battery (200) of the present invention may include a pouch-type battery case (210) according to the present invention.

[0185] According to one embodiment of the present invention, the pouch-type secondary battery (200) may include a pouch-type battery case (210), an electrode assembly (260), an electrode lead (280), an insulating part (290), and an electrolyte (not shown) according to the present invention.

[0187] Hereinafter, each configuration of the pouch-type secondary battery according to the present invention will be described in more detail with reference to FIG. 1.

[0188] At this time, the pouch-type battery case (210) according to the present invention is omitted as it has been described above.

[0190] (1) Electrode assembly (260)

[0191] The electrode assembly (260) can be inserted into a pouch-type battery case (210) and sealed by the pouch-type battery case (210) after the electrolyte is injected.

[0192] The electrode assembly (260) may be formed by sequentially stacking an anode, a separator, and a cathode. Preferably, the electrode assembly (260) may include two types of electrodes, an anode and a cathode, and a separator interposed between the electrodes to insulate them from one another.

[0193] The positive and negative electrodes may each have a structure in which an active material slurry is coated onto an electrode current collector in the form of a metal foil or metal mesh containing aluminum and copper. The slurry can typically be formed by stirring granular active material, an auxiliary conductor, a binder, and a conductive material with added solvent. The solvent can be removed in a subsequent process.

[0194] An electrode assembly (260) can be manufactured in a predetermined shape by applying a slurry, which is a mixture of an electrode active material and a binder and / or a conductive material, to an anode current collector and a cathode current collector to manufacture an anode and a cathode, and stacking them on both sides of a separator. The types of electrode assemblies (260) may include stack type, jelly roll type, stack and folding type, etc., but are not limited thereto.

[0195] The electrode assembly (260) may include an electrode tab (270).

[0196] The electrode tab (270) is connected to the positive and negative electrodes of the electrode assembly (260), respectively, and protrudes outward from the electrode assembly (260), serving as a path for electrons to move between the inside and outside of the electrode assembly (260). The electrode current collector included in the electrode assembly (260) may be composed of a portion coated with an electrode active material and a terminal portion not coated with an electrode active material, i.e., a non-coated portion. The electrode tab (270) may be formed by cutting the non-coated portion or by connecting a separate conductive member to the non-coated portion using ultrasonic welding or the like. As shown in FIG. 9, the electrode tab (270) may protrude in different directions from the electrode assembly (260), but is not limited thereto and may be formed to protrude in various directions, such as protruding in parallel from one side in the same direction.

[0198] (2) Electrode lead (280)

[0199] The electrode lead (280) can supply electricity to the outside of the pouch-type secondary battery (200). The electrode lead (280) can be connected to the electrode tab (270) of the electrode assembly (260) by spot welding or the like.

[0200] The electrode lead (280) is connected to the electrode assembly (260) and can protrude outside the pouch-type battery case (210) via the sealing portion (250). Preferably, one end of the electrode lead (280) is connected to the electrode assembly (260), specifically the electrode tab (270), and the other end of the electrode lead (280) can protrude outside the pouch-type battery case (210).

[0201] The electrode lead (280) may include a positive lead (282) that has one end connected to a positive tab (272) and extends in the direction in which the positive tab (272) protrudes, and a negative lead (284) that has one end connected to a negative tab (271) and extends in the direction in which the negative tab (271) protrudes. Both the positive lead (282) and the negative lead (284) may have their other ends protruding to the outside of the battery case (210). Thus, electricity generated inside the electrode assembly (260) can be supplied to the outside. Additionally, since the positive tab (272) and the negative tab (271) are formed to protrude in various directions, the positive lead (282) and the negative lead (284) may also extend in various directions. The positive lead (282) and the negative lead (284) may have different materials. That is, the positive lead (282) is made of the same aluminum (Al) material as the positive current collector, and the negative lead (284) may be made of the same copper (Cu) material as the negative current collector or a copper material coated with nickel (Ni). A portion of the electrode lead (280) protruding outside the battery case (210) can be a terminal portion and electrically connected to an external terminal.

[0203] (3) Insulating part (290)

[0204] The insulating portion (290) prevents electricity generated from the electrode assembly (260) from flowing through the electrode lead (280) to the pouch-type battery case (210) and can maintain the sealing of the battery case (210). To this end, the insulating portion (290) may be formed of a non-conductive insulating material that does not conduct electricity well. Generally, the insulating portion (290) is often made of insulating tape or film that is easy to attach to the electrode lead (280) and has a relatively thin thickness, but is not limited thereto, and any material capable of insulating the electrode lead (280) may be used.

[0205] The insulating portion (290) may be positioned to surround the outer surface of the electrode lead (280). Preferably, at least a portion of the electrode lead (280) may be surrounded by the insulating portion (290). In this case, the insulating portion (290) may be positioned between the electrode lead (280) and the pouch-type battery case (210). The insulating portion (290) may be located in a sealing portion (250) where the first case (220) and the second case (230) of the pouch-type battery case (210) are heat-fused, and the electrode lead (280) may be bonded to the battery case (210).

[0207] (4) Electrolyte

[0208] The pouch-type secondary battery (200) according to the present invention may further include an electrolyte (not shown) injected into the inside of the pouch-type battery case (210). The electrolyte is intended to move lithium ions generated by the electrochemical reaction of the electrodes during charging / discharging of the secondary battery (200), and may include a non-aqueous organic electrolyte, which is a mixture of a lithium salt and an organic solvent, or a polymer using a polymer electrolyte. Furthermore, the electrolyte may include a sulfide-based, oxide-based, or polymer-based solid electrolyte, and such a solid electrolyte may have flexibility that allows it to be easily deformed by an external force.

[0210] battery module

[0211] The battery module according to the present invention may include a pouch-type secondary battery according to the present invention.

[0213] According to one embodiment of the present invention, the battery module may include a plurality of pouch-type secondary batteries according to the present invention. For example, the battery module may refer to a battery assembly in which a certain number of pouch-type secondary batteries are bundled and placed in a frame to protect them from external shock, heat, vibration, etc.

[0215] According to one embodiment of the present invention, the battery module may be used as a power source for one or more medium-to-large devices, including a power tool; an electric vehicle (EV) and a plug-in hybrid electric vehicle (PHEV); or a power storage system.

[0217] battery pack

[0218] A battery pack according to the present invention may include a battery module according to the present invention.

[0220] According to one embodiment of the present invention, the battery pack may include a plurality of battery modules according to the present invention. The battery pack may refer to the final form of a battery system mounted on a vehicle, etc.

[0222] According to one embodiment of the present invention, the battery pack may be used as a power source for one or more medium-to-large devices, including a power tool; an electric vehicle (EV) and a plug-in hybrid electric vehicle (PHEV); or a power storage system. Explanation of the symbols

[0224] 200: Pouch-type secondary battery 210: Pouch-type battery case 220: First case 222: Cups 224: Reception Department 230: Second case 232: Cups 240: Terrace section 241: 1st Terrace Section 242: Second Terrace Section 243: Third Terrace Section 244: 4th Terrace Section 250: Exterior wall 260: Electrode assembly 270: Electrode tab 272: Positive tab 274: Cathode tab 280: Electrode Lead 282: Positive lead 284: Cathode Lead 290: Insulation part 301: Cup 302: Reception Department 303: Punch Corner 401: Punch Edge 402: Die Edge 403: Thickness edge

Claims

Claim 1 A pouch-type battery case comprising a cup portion that accommodates an electrode assembly formed by laminating electrodes and a separator, wherein the cup portion comprises an edge portion, the cup portion comprises a refractory layer disposed on the edge portion, and the refractory layer comprises a foaming agent comprising one or more selected from the group consisting of hydrated alkali metal silicate and hydrated alkaline earth metal silicate. Claim 2 A pouch-type battery case according to claim 1, wherein the edge portion connects a plurality of outer walls surrounding the periphery of the cup portion and a bottom portion, and includes a plurality of punched edges formed by rounding. Claim 3 A pouch-type battery case according to claim 1, wherein the edge portion connects a plurality of outer walls surrounding the periphery of the cup portion and a terrace portion, and includes a plurality of die edges formed by rounding. Claim 4 A pouch-type battery case according to claim 1, wherein the edge portion connects a plurality of outer walls surrounding the periphery of the cup portion and includes a plurality of thickness edges formed by rounding. Claim 5 A pouch-type battery case according to claim 2, wherein the edge portion comprises a punch corner formed by connecting two adjacent punch edges. Claim 6 A pouch-type battery case according to claim 1, wherein the refractory layer comprises a foaming agent comprising a hydrated alkali metal silicate. Claim 7 A pouch-type battery case according to claim 1, wherein the refractory layer comprises a foaming agent comprising hydrated sodium silicate. Claim 8 In claim 7, the pouch-type battery case, wherein the hydrated sodium silicate is represented by the following chemical formula 1: [Chemical Formula 1](Na2O)·x1(SiO2)·n1(H2O) In the above chemical formula 1, 2≤x1≤5, 0.1≤n1≤10. Claim 9 A pouch-type battery case according to claim 1, wherein the refractory layer further comprises one or more materials selected from the group consisting of inorganic fillers and resins. Claim 10 A pouch-type battery case according to claim 9, wherein the inorganic filler comprises one or more selected from the group consisting of titanium dioxide, alumina, kaolin, zirconia, silica, zinc oxide, and boehmite. Claim 11 A pouch-type battery case according to claim 9, wherein the resin comprises one or more selected from the group consisting of styrene-butadiene rubber, phenol resin, polyester resin, epoxy resin, polysiloxane resin, polyurethane resin, polyvinyl acetate, carboxymethylcellulose, and nitrile rubber. Claim 12 A pouch-type battery case according to claim 1, wherein the refractory layer has a thickness of 1 μm or more. Claim 13 A pouch-type battery case according to claim 1, wherein the refractory layer expands at a temperature of 130°C or higher. Claim 14 A pouch-type secondary battery comprising a pouch-type battery case according to claim 1. Claim 15 A battery module comprising a pouch-type secondary battery according to claim 14.

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